Does Crank Length Affect Your Cycling Performance? The Science

[@JessicaSeverin]

I'm 5'6" and always had 170 or 172.5 (what came on the bike). after decades of cycling and knees getting progressively worse, I finally special ordered a 165mm crank. it really reduced my knee pain. Crank length might not affect peak performance, but it will alter your bio-mechanics and might reduce the strain on your joints. definitely worth experimenting.

[@old_papa]

Definitely agree with this. Ex-competitive skier with ancient (mid 80's) ACL replaced right knee (also scoped several times over the decades), lots of arthritis - no more repair is possible so next step down the road is knee replacement. A few years ago I got an indoor trainer that I set up identically to my road bike with the exception that it had 170 cranks. It was amazing how much less knee pain I had when indoor training vs outdoor. So I decided to change the cranks on my road bike (from 172.5 to 170). When you have compromised cartilage or arthritic surfaces even tiny differences can make a big difference in comfort. With slightly shorter cranks, my knee is less extended at the bottom and less flexed at the top. For whatever reason, this now keeps my knee more on the remaining cartilage than aggravating the arthritic surfaces. I can now cycle long distances again, and go multiple days cycling without any knee pain. Definitely worth experimenting if you have bad knees.

[@FreemanBR]

This!!! I was expecting the video to cover this scenario and others related to crank length and bike fit, body and joints injury prevention. I have had knee issues for the last 5 years or so, moved to 165mm cranks and it has drastically reduced the knee pain I feel. Pair that to actually keeping an eye at cadence and I can produce more power and be safe fory joints!

[@umaxi96]

How about saddle position and clip position on shoes?

[@JessicaSeverin]

@@umaxi96 yes I was always adjusting those too trying to get the perfect most pain free position, but it wasn't until I switched to the 165mm that I was able (along with new saddle and toe position) to really dial it in. It has to do with making the distance from max top to max bottom smaller so there was less extreme bend at the top of the stroke for my shorter legs. With the 165mm my knees were 10mm lower (less bend) at the top of the stroke.

[@330_Crew]

Interesting. I’m 5’6” as well and my 175mm cranks are driving my knees nuts.

[@AdamHansenOfficial]

Hey you mentioned me!!!! Thanks

[@stephenstarks9043]

Hey, Dylan! At 2:40 you said something that really caught my attention. You mentioned that a change in saddle height can make an 8% change in power. How 'bout doing a video analyzing that? I would really like to know if my saddle is too high

[@mua6887]

Stephen Starks +1

[@pbarr1935]

@@mua6887 +2

[@ryanphillips713]

Stephen Starks +3

[@TheAndreMD]

+4

[@PedalandTrek]

+5

[@pbarr1935]

Most dependable, accurate cycling info on YT. Thanks for successfully avoiding the "Lets just throw some content out there so we keep getting hits" syndrom. MUCH appreciated!

[@clydea.hutchisoniv5742]

tomorrow GCN will have a video on this topic

[@Cookefan59]

The man who never blinks. Never flinches and always come with strong solid research to back up that unblinkinging profile. Thanks for this. I’ve always wondered about this being 6’3” tall.

[@warrenundso4685]

hahah this was not wasting time at all. very informative. Love that you back it up with scientific studies.

[@TrailFeatures]

At 6'2 w/33" inseam, 165 is my fave across all disciplines. Good cadence on road/gravel, and maximum clearance on MTB. Great vid!

[@BlackWaterCyclist]

I am the same height and my favorite is 165 to 170 but I will not go over 170. Its awesome on the MTB to go shorter, you can hit those higher peak powers quick and accelerate better in tight and technical terrain.

[@fiddleronthebike]

I use 180 mm cranks on all my bikes for almost 40 years. Nowadays everybody tells "shorter is better" and even people with my leg length (90 cm inseam) are told to go for 165 mm by many bike fitters - but whenever I ride a bike even with 170 or 172.5 I find it uncomfortable, and I have no problems whatsoever with knees or hip, not on the road bike, not with CX and not even with the TT bike. So why go shorter? And btw, especially as I get older now I believe it is a good thing to use the range of motion you have got... you know: use it or lose it😎 Thanks for that video and showing that there is no real evidence for the benefits of shorter cranks! ...btw: with my 180 mm cranks and 900 mm inseam I am exact spot on with that 20% mentioned in one study...

[@mreyes2633]

I usually don't comment about my cycling experience... but this hits a huge part in my cycling experience... First, I think its individual preference and can go either way... for my experience, I'm 5'3 or 160cm tall, I started with 170mm crank. I built an Allez with 160 crank, and kept my Ridley Helium at 170. I noticed a drastic difference. I noticed the 160 took more pedal pressure on climbs than 170 (makes sense with how torque is generated). I then tried to see if my sprints were better with 160 (Just like the video concluded, higher rpm, optimal power output)... and they were. I settled back for 170, cause real world riding have inclines everywhere and I felt my sprint gains weren't advantageous enough than the lost in climbing torque during my rides

[@Hexsense]

or... just fit lower gear ratio with the 160. You produce less torque but can spin (and prefer to spin) faster. So dial down the gear ratio.

[@mreyes2633]

@@Hexsense I actually did that too, I went with 50/34 on the 160 and kept 52/36 on the 170... the gearing was still not enough. Maybe with this new Sram AXS, 46/33 paired with 10-33 cassette, maybe... but for the price...

[@cccpkingu]

What gearrange are you in, and what gears do you have?

[@Hexsense]

​@@mreyes2633 change from 170 to 160 reduce torque by 5.9%. Changing from 36 to 34 is 5.6% lower gear, which is pretty close. One more tooth in the cassette would overcompensate it by many percentage. Once you have sufficient low gear to reach comfortable cadence, torque would not be the limiting factor anymore. It shift back from torque to power as the limiter like most of other situation.

[@mreyes2633]

@@Hexsense ok cool, torque and power are directly proportional as well as rpm... check this: Power = torque * rpm Given a steady pedal pressure.... 170 crank > torque than 160 crank If a rider can max spin a pedal at 130 rpm both 170 and 160 pedals... 170 has > power than 160.... Which isn't real world case cause I can max spin a 160 crank > than a 170 crank...which supports my finding and the videos finding that shorter crank can produce more power... What I noticed, was with reduced gear with 160 at 50/34 chain ring, I'm still producing slower speed up inclines. 50-28 gear (160) vs 52-28 (170), the 170 gave me faster climbing speed given 90 rpm for both. It makes sense for track riders, cause there's no incline in a velodrome. I've invested enough money and tested as objective as I could to understand that I'm better off with 170 than 160 based on real world riding.

[@Siravingmon]

Astounding! A bike channel that actually refers to different sources of research. Well done and thank you!

[@theadventurebiker]

Great info!!!!!! I ran an [unscientific] experiment some years back where I tried riding my mountain bike (the same bike) on the same routes (both road and offroad) using 170, 175, & 180mm cranks. I noticed the same effects on cadence that you've mentioned. I also felt that I generated less torque (like when accelerating out of a corner), but a higher RPM (like when riding fast down a straightaway) with the 170mm cranks than the others (so better top-end). Because of this I found myself sometimes selecting a gear lower and riding at a higher cadence to get my best performance. On the flip side I felt that I could produce noticeably more low-end to mid-range torque (to put it in automotive terms) with the 180's but at the expense of top-end RPM. This was very good when that extra grunt was needed to get up and over punchy climbs, accelerating out of slow corners, etc. But because I felt that my top end cadence was somewhat limited I found myself shifting into higher gears earlier (instead of "winding them out") to compensate and take advantage of the greater torque at lower RPM's. Maybe it was my imagination but the effects and differences felt very real to me.

[@billholmes6639]

This makes complete sense to me. Due to a knee bending issue I went down to 115mm cranks (yeah, like 4"). I have no problem keeping up with any of my cycling buddies whatsoever. My cadence is higher however, the actual foot speed is lower as the peddling circle is much smaller. My times up local climbs from 20 years ago are about the same even though I'm 68 now.

[@briandewey5401]

115 mm cranks? custom made? never heard of any pro cranks this short

[@cusebike5391]

I'm 71 years old. In the past several decades, I've used 165's to 180's for extended periods. I was 6'3" when I did all these changes (I'm now 6'2"). Thanks to the U.S. Army, I learned that my leg length is disproportionately in my femurs. That coupled with size 48 shoes, I'm pretty far out on the crank compared to most. I liked 180's but my knees didn't. I've been on 175's for the past 20 years and it works. Where your leg length is and how long your feet are is more important than just an inseam number. All said, ride what's most comfortable.

[@mwagoner12]

Hey Dylan, love the channel. I'm an older guy that does not race just loves to ride. My wife, who pretty much won't touch a bike loves to watch also. We wait each week for your new upload and put it up on the 60 inch screen! Never disappointed. Some times I'll start out a sentence when speaking to her. "Dylan says..." and you really have taught me a lot. So thanks! It'd great to have you follow me on Stava. Wishing you success going out on your own. God speed.

[@DoraeMew]

From 2:15, I know a male rider who use 150 mm crank length not for a power production nor a bike fitting reason. He use it just to have enough saddle height to avoid seatpost hitting with reservoir tank of his Specialized Shiv Disc (2020). The crank is Rotor Aldhu and I believe Rotor make this Aldhu crank range from 150-175 mm for a good reasons.

[@NewEnglandDirtRoadie]

meanwhile, on GCN: how to clip in to clipless pedals... AGAIN

[@mileshall9235]

But you get all those British accents!

[@natgeoba7377]

Or how to watch a race like a pro. Talk about good timing

[@workingguy-OU812]

@@mileshall9235 And we get marketed bicycles with out-of-round bottom bracket holes! What more could we want?!

[@chrisprice6206]

yeah its youtube's way of directing us to "properly controlled content" no offence to GCN, certanly not the hosts but its about $$$. my kids carseat was made by essentally cannondale(parent company)

[@danielandersson3539]

Haha, and the only difference from the first two clip-in videos is that someone launched some new stuff they want some cool advertisement for!

[@stanandre4539]

For triathletes / people spending time in tuck / aero position, shorter cranks are often said to help, as they constrict breathing less (you don't get you knees up your chest so much). Now whether there's a study to show that, idk. But if it subjectively improves comfort, then it's probably worth it.

[@scottfrisby4510]

And yet another question thoroughly answered! Thanks, Dylan.

[@fasdiablo]

Interesting !! . . . I've just changed down from 175 to 170. I decided to do it as I felt a 'dead spot' when peddling from around the 11 o'clock to 2 o'clock position, the change seems to have improved my perceived peddling action and making riding easier and more efficient . ..

[@angeloviray4916]

fasdiablo what is your Height....currently im using a 175mm crank...it's hard to spin fast

[@marchollander7392]

Hi Dylan, great research and video...keep it up 👍 Maybe it would have been worthwhile noting in the video that shorter crank length could be beneficial in aerodynamics on a time trial bike and for “opening up the hips” on a triathlon bike.

[@RunPJs]

This is well put together. My takeaway message is that if I change from 172.5 to 165 then I'll finally be able to use my aerobars properly (due to higher saddle) - well that's the plan! I just have to see if I'm comfortable and generating my normal power with the changes.

[@equus123]

Female, 5’5” tall, long femurs, 155 cranks. That was one of the profound changes I made to my fit about 1.5 years ago. I always had a pinching on the right front of where I contact the saddle. After zeroing in on a good, low saddle height for myself, I visited my fitter and his rig can adjust crank length. As I rode, we shortened down from my 170s and 155 was the magic number that removed that pinching. It was the length that created pelvic stability and a pressure down on the whole saddle through the entire pedal circle. I had never experienced pelvic stability like this before. Essentially, anything longer than 155 resulted in the front sides of my pelvis lifting as my leg came over top of the pedal stroke. I had lived with saddle sores for 11 years before I got my bike fit + crank length sorted.

[@Dralbastaki]

what if u went to 145mm? maybe u would be able to remove spacers and go lower?

[@christophertan3195]

​@@Dralbastaki less crank length creates higher seat posts

[@boogiexx]

I'm 180 cm, 81 Inseam, had 175 mm, switched to 170 mm, night and day difference, I don't care so much about the performance I mostly care about comfort during long rides, after I changed I didn't have knee or muscle pain no matter how long I rode my bike and trust me when I say that I tried all saddle heights from too low to too high and everything in between on 175 set up, that is because you can effect the low point with saddle height but the highest point is affected by the crank length 1 major thing I noticed is that before the change I would get the rocking out of the saddle sensation like my hips are jumping during high cadence intervals, now those are completely gone and my body is telling me that the change was good. I was inspired by the Neill Stanbury bike fitting videos on Cam Nicholls channel some cool stuff there.

[@creeppin]

Hey Dylan. I am paralyzed and ride a handcyle. For me I found using a longer crank arm gave me a little more torque, but it also caused me to use a higher gear because I couldn't spin at the cadence I like. Great video!

[@LeBator]

Height 189cm. Inseam 88cm. My first bike came with 165mm cranks. I found I was constantly raising the saddle to get comfortable. Switched to 175mm and have been riding 40+ years comfortably.

[@ronetele13]

Well, that’s a surprisingly interesting finding! Two things that were missed: - As using shorter cranks indicates a higher optimal cadence, then gear ratios also should be changed - shorter cranks, higher cadence, lower gear. As well, of course, longer cranks, lower cadence, higher gears - for the same speed & effort level. - Higher cadence makes it easier to react to speed increases in group riding. To match a group acceleration, it’s more effective to spin up than it is to mash the pedals at lower cadence (& higher gear). For one thing the pedals are coming over the top sooner at faster cadence. Also, what’s the data on knee (other joints too) injury related to cadence at the same load (wattage)?

[@nwimpney]

it being "more effective to spin up than mash" is making some assumptions about what's ideal for the rider. If I'm doing 90RPM on my 180mm cranks (typical for me), and want to speed up 10% to match a group acceleration (99 RPM), that's not any harder than if I was doing 100RPM on my 175mm, or 130RPM on my 165mm, ans speed up to 110RPM, or 143RPM respectively. Anecdotally, I get sore knees when I do longer rides on shorter cranks, so the seemingly conventional wisdom of shorter cranks being easier on the knees is definitely not always true. That said, I'm tall with very long legs, and already ride with a relatively fast cadence most of the time, so what's better for my knees is probably very different than someone who's short and naturally mashes at a low cadence. While I'm likely better off spreading out the power over more of my comfortable range of motion (reducing force) at the same power, someone short who's pushing the limits of their range of motion is probably going to benefit from bringing it down to something more reasonable, while maintaining their power through a higher cadence.

[@ronetele13]

@@nwimpney Good point & well-said. Indeed, it would have been better if I had said something about cadence being relative & so for each individual spinning at the higher cadence of their comfort range in order to better stay tight in a group. Right?

[@obikedog]

Thanks for this in-depth review. Not exactly what I expected based on personal experience but I trust the science. So not very scientific because my chainring sizes also changed but @ 5'6" and long-time 165 crank user, I switched up to 170 when I bought my GRX (48/31) gravel bike. Interestingly, on longer rides and races I noticed both knee and achilles pains I hadn't experienced before. I chalked this up to the new bike, its fit, and didn't really look at the cranks suspiciously - maybe because GRX doesn't come in 165, so I was stuck. I kept my Cannondale 165 (50/34) on the trainer and was seeing sprint power over 1.1kw easily during 4dp tests but on the 170s struggled to peak 900w at while attaining a decent sprint cadence. Last week I switched out my gravel bike to Ultegra 165 matching the Cannondale and found my interval sessions are easier to complete at higher powers and longer durations and my joint/tendon issues have not reappeared on rides over 80mi. (note - Power meter was reset to match the new crank length.) My sprint on the road now matches what I can do on the trainer. I think this melds well with the science; that we need to experiment and find the crank that allows our preferred cadence; fits our biometrics and metabolism. Now I only wish Shimano would make a GRX 165 crank.

[@mattgeyerful]

Bit of an old video but I changed from 175 to a 165 crank recently (I'm 5'7 with a short inseam of 28in) and was surprised with how much more comfortable it was, particularly when standing. Didn't notice any tangible differences in power but I'll take extra comfort any day

[@SteveHofsaess]

According to this study, If I want to keep my 172.5 mm dura ace crank arms, I must shorten my legs by 2mm

[@mosaiahzionwilliams835]

🤣🤣🤣

[@actualperson1971]

You can probably try a cycling shoe with a thinner sole

[@ernestoechevers4741]

Go skydiving that shortens people if they land hard too many times

[@mileshall9235]

In terms of the physics, increasing the crank length is somewhat like making your back ring slightly bigger. You move further to get the same input, therefore the resistance is less. Because we have so many options for resistance with gears it's not easy to feel the slight change. However if you have two single speeds with the same gearing, but with a difference of 10-15mm in the cranks, you can feel the shorter cranks giving you more resistance, as though you shifted up one gear. The reason the 165'rs were doing more RPM's was they had to downshift to attain the same lighter resistance as the 175'rs. The velocity of the feet was the same even with the higher RPM of the 165'rs - if you imagine the distance around the circle. Pi x diameter = circumference, so if the two cadences had stayed the same, the feet would be traveling 518 mm to go around with the 165s, 550mm with the 175s. So more torque with the 518 to get the same distance out of the wheel. Inversely, to cover the 550mms the 165s need 1.06 revolutions compared to the 1 revolution for the 175s. So 6% higher cadence. Simple math. Another way to imagine this is if you had a bike with two chains. A ring in the front pulling a second ring in the middle, directly attached a third ring with the second chain, which spins the fourth ring on the back wheel. If that second ring gets bigger, what happens? (just like your bigger ring typically on the back wheel) -- less resistance. Your legs are that first chain and the cranks are that second ring. Hope this doesn't sound convoluted, it's actually quite simple. Purely ratios. The absolute simplest way to imagine it is with no chain, and your cranks directly spinning the back wheel . Longer cranks would basically be the same as a bigger back ring. Of course this doesn't address leg length, preference or performance. Just the Newtonian side. Hope I didn't take all the fun out, LOL

[@sixstanger00]

This really shouldn't even be a question. Anyone who's ever had to loosen a bolt using a breaker bar understands the concept of leverage. The crank arm is doing exactly what a ratchet does to a bolt - applying twisting force. The longer the bar, the more force is applied. A longer crank arm is going to provide greater leverage, and thus each pedal stroke will apply more force than the same stroke with shorter arms. Yes, shorter arms let you spin faster, but why would you want to? It's not like you're gaining anything; a rider with short cranks will have to spin faster in order to match the speed of a rider with longer cranks, so basically shorter cranks just means you have to work harder to get the same result. The only reason a shorter crank length is desired is on a MTB, where ground clearance becomes an issue. Downhill bikes for example, will likely have short cranks because gravity propels them most of the time. An XC bike on the other hand, uses longer cranks because a great deal of it's time is spent pedaling. My XC bike has 175mm cranks. I wouldn't dare go shorter - shorter arms means I have to work harder to apply a given amount of power. Regarding leg length, that's not really going to be a factor provided the rider has saddle height set optimally. Short leg or long leg, a longer crank arm is still going to offer more leverage. The distance between the center of the crank axle & the tip of the crank arm is going to be same, no matter the size of the rider's leg. Thus, the number of strokes needed to produce X amount of speed is the same regardless of leg length, because the circumference of the pedal stroke is the same. Provided the rider has their saddle set so that each pedal stroke almost fully extends their leg, they will apply maximum power on each stroke.

[@mileshall9235]

It will not effect the bottom of the stroke if a shorter legged person has the longer crank. (Assuming the seat height is set correctly as you point out.) But it will certainly still effect the top of the stroke. Leg length is another lever size, and the difference in angle between tibia and femur could be greatly affected, depending on how short of legs we are talking about here!! imagine yourself riding on a 200 or maybe even 240mm crank, how much more bent your knee would be at the top. Once again, that angle is part of the leverage equation.

[@sasquatchrosefarts]

@@sixstanger00 you're forgetting losses to friction. Pushing big cranks means more chain tension and this definitely affects mechanical efficiency in both chain and bearings in the bottom bracket and rear hub. It's never simple, and there's always a trade-off.

[@sixstanger00]

@@sasquatchrosefarts The crank arm length will not change the amount of friction on the chain/hub, because the chainring is still the same diameter. The chain engages with the chainring, not the crank arms. A longer crank arm simply provides more leverage to rotate the assembly easier. But the chainring and chain itself will experience the same amount of friction at 80 RPM, regardless of crank arm length. The only way you can increase friction at the chainring is by increasing it's diameter and thus adding contact points between the chain/teeth. As for chain tension, the weight of the bike/rider is fixed, so the drive wheel will require a fixed amount of energy to spin, regardless of arm length. The longer arm, just like a breaker bar on a bolt, allows you to apply that energy _easier._ But ultimately, the chain will experience the same tension in a given gear selection, because regardless of the crank arm length, the _weight is still generally the same._ A longer arm doesn't mean you apply *_more_* power, it just means that applying X amount of power on 175mm cranks will be easier on your legs than 165mm cranks.

[@sasquatchrosefarts]

@@sixstanger00 more torque and lower rpm is more tension on the chain. Get off the meth bro

[@RoyDeWeese]

I am 5’4” with a 26” inseam. I went to a shorter cranks 155cm and my decision was not for power or cadence it was for comfort. Let me explain. When you are vertically challenged like I am and the manufacture puts 165cm/170cm cranks that now means I have to lower my seat to be fitted properly;however, now at the top of the pedal stroke my knees felt like they were coming to my chest and they were. My legs would hurt. It felt like I was doing high knee exercises for 30 miles, so I started looking into crank length and settled on 155cm and my legs felt great from day one. Think about it.

[@Chris-de2qc]

I'm 5'2" and ride with 165/170 on my 2 bikes... Where did you end up getting 155? And how much did you raise your saddle?

[@RoyDeWeese]

Chris I have Cobb and Vision TTiMAX

[@simedinson984]

@@RoyDeWeese i am 6 3 i think and about and over 34 inseem not exactly sure how much but i have the same problem with my knees hitting my chest

[@michaelkennedy9031]

As a triathlete doing Ironman I am looking into 165 to open up hip angle

[@Jeppelelle]

As a semi-fat non triathlete: what does opening up the hip angle entail?

[@chrisprotzman6637]

Jesper Andersson When on a triathlon bike (or drops on a road bike) you are put in an aggressive position, where the longer the cranks the closer your legs will get to your chest when pedaling. With a smaller crank length the angle between your back to pelvis to knee is not as extreme, thus the term opening hip angle.

[@jameseaves71]

I use 162.5 on my triathlon bike. It helps immensely in getting aero.

[@davethedogdude]

I am 5'11" and I ride 165s. I like to spin, it helps me spin smoother. It keeps my knees and my hips much happier then 175s or even 172.5s. I can get into more aero position because of the raised saddle height. I actually would consider going even smaller if I was going to replace my cranks again. On my old TCR with 175s my knees would be pounding my chest if I was in the position I can ride now.

[@jameseaves71]

A bigger chain ring and lower cadence with the shorter cranks works perfectly for Ironman. John Cobb has done heaps of work on this topic.

[@OneWheelLess]

Really cool, I used to do a fair amount of distance on unicycles, most with 29” or 36” wheels. For unicycles, crank length is super important. It’s common to be able to find unicycle cranks from 115mm to 175. Because they’re low geared and fixed crank length is almost like changing gears. For distance on road or gravel 125-135mm cranks were ideal for spinning and 140-150mm were great for power off road but not as spin-able. 175s would wear me out quickly and definitely were not as smooth. I ride Singlespeed a ton, and I think that crank length is more important than with geared bikes. I like to spin, I think probably 160 would be amazing for my Singlespeeds.

[@theadventurebiker]

^^^ this should be a pinned comment! 👍

[@nwimpney]

It's worth keeping in mind though that because of the lack of gearing, you're having to use shorter than ideal cranks just to allow a high enough cadence. I run cranks around 100mm on my unicycle with 700c 25mm (typical road bike) wheels to allow a silly high cadence just to be able to ride at jogging speed. So, in the case of trying to go fast on unicycles, it's not so much choosing the "ideal" length, as it is choosing the shortest cranks that you can manage to balance on. (If you're not smooth, you won't have enough torque to recover if you get off balance, and you'll crash) Pretty much everyone, including short people, are using cranks that are way too short for them on the unicycle. It's just a limitation of being direct drive. A good comparison would be measuring your power output with different crank lengths while leaving the bike in its lowest gear. Most riders will make more power the shorter the cranks are, because they're almost purely cadence limited, not torque limited.

[@PLMassTahh]

Finally well made video on the topic. Thanks mate!

[@clydea.hutchisoniv5742]

with a longer crank arm your foot has to travel farther and faster to produce the same cadence, this fact may explain why preferred cadence goes up with a shorter crank because the speed your foot is moving might determine your preferred cadence

[@mileshall9235]

Basically what I say above but you did it with 20% of the words. It does explain it, along with preferred resistance.

[@weldonyoung1013]

But there is also another consideration - heart rate. With divergent heart rate and cadence the perceived effort can increase.

[@AdamHansenOfficial]

I worked it out one day and to have the same leg speed with a 180mm crank and a 172.5mm(I think it was that one I was comparing it to) the 180mm crank needs an RPM of 95 while the 172.5mm needed 100 RPM to have the same leg speed

[@LEFTY4U]

I set up MIni “12 y o female NEHSCA rider/racer” with 150mm cranks on an adult XS stumpy. Stock was 165mm she was losing about a half pedal stroke. Also drop ring size down from 32 to 30 oval with the shorter crank. World of difference watching her ride now.

[@DavidSkater7096]

Great video Dylan. When I rode track, the key advantage to shorter cranks was less pedal strikes on steep banks at slow speeds

[@OTBTBDA]

I run 210mm cranks and love it!!! I have no problem holding 105RPM for +2hrs when riding indoors. I have been racing since 1988 and I rode 180mm until I found the 210mm about ten years ago. When I want accelerate it is like having motor on my bike I just take off. Keep in mind I have long inseam but longer cranks allow me to run a smaller bike. I am supposed to be on 63cm frame but ride a 56-58cm frame. I am 5"11' with a 37inch inseam and weight 190lbs and my race weight is 155lbs...ya I am over weight!!! I like that I can use make more use of my Hamstring muscles. I hear many saying because the diameter is long that it takes longer to turn the pedal. This is absurd thinking! As long as the crank is turning there is power being generated!!! 4 hrs. of pedaling is 4 hrs. of pedaling. I'd rather more use of muscles than limit the range of motion my leg muscles go through. What I find baffling is the cycling community continues to attempt to rewrite the laws of physic. A longer lever will always be more efficient. I put 210mm cranks on my MTB and it was a dream I could ride at any cadence and have no problem riding up steep hills (I just need to drop 30lbs-40lbs!!). When it comes to running crank length test the test has be over a period of weeks and months because your muscle have to adjust to the range motion/pedaling habits. Why does cycling think a long crank leads to low RPM's when the longer lever makes it easier to turn the chainring...so how does that equate to making it more energy consuming? Many cyclist act as if the race is won by who can spin the crank arm the fastest when instead it who can turn the rear wheel the fastest. I did some research and found that almost all holders of the hour record use cranks at 195mm un length. The Hour attempt is considered the hardest bicycle test. So if it is so hard why use longer cranks if longer crank use more energy? I will say this because it is easier to turn the pedal you can start to day dreaming and pedal with less effort thus pedaling slower. I find as long as I pay attention my RPM meter it is great. Another cool point is when I am tired on flat road with a tail wind I can put the bike in a hard gear and just coast along (like over drive).

[@1carusjohn32]

Dylan, I looked at this a lot about 3 years ago. I think the answere is disciplin specific.. tracksters use short cranks. In my case, I was riding 175 and had issues with both my knee and hip angles when on the drops. I actually bought second hand cranks from 165 upto 175 at 2.5mm increments. I settled at 170, 167.5 was prob the best but it was marginal on how it felt, and I couldnt get thrm in the brand/range I wanted . Here's the thing though, its only a 5mm difference, but as it is shorter it alows the saddle to be lifted 5mm for the same leg extension angle, the benefit comes at the top of the stroke as your saddle is now 5mm higher and the pedal 5mm lower. This really helps both your knee and hip angles. Effectively like raising your original saddle set up by 10mm, which eases knee and leg angles particularly if you are on the short side of the mean. For longer distances this made a massive difference to me. It wasnt about how much power it was about comfort and ease of power for me.

[@sapinva]

Short cranks on the track are also to avoid pedal strikes on the banked surface. The flaw for crank length arguments is that the dominate lever of the system is your femur, which you only get in the length you are born with.

[@Hexsense]

sad to born with short lever.

[@moviepedro]

you have to be going really slow (like 8mph) to pedal strike on the track... on flat ground its another story (for fixed gear crits)

[@nwimpney]

@@moviepedro I've banged my pedals lots of times when manoeuvring on the straights, which need to be banked to a lesser degree so you're not climbing such a hill entering the corners. Quickly moving over to the right (up the track) on the straights is how I've frequently hit them. I've also done it when I dropped down a little sharper than usual in a sprint, and had to turn back to the right to straighten up. (going quite fast)

[@moviepedro]

nwimpney oh ok! What length cranks were those?

[@nwimpney]

@@moviepedro 165mm. That is making some unusally aggressive turns, though. And it also depends a lot on the track. outdoor tracks aren't likely to have a problem. The track I was riding on is 200m indoor, and around 47 degrees in the steep banking, 15-20 (my guess) on the straights. They say 30km/h is around the minimum speed for the corners on that track, but if you've got a relatively high bb, and 165mm cranks, you can go pretty slowly on the banking if you're very smooth. I think most of the crashes from slow riding in the steep banked corners are actually traction related, or people turning outward too agressively. Tire slides out, and then the pedals hit the ground after. It's a little counter-intuitive, but all the pedal strikes I've had were from turning outward on the straights.

[@dwaynerandolph3565]

When I started road cycling in 2000 I used 172.5 mm cranks for 16 yrs. Now I ride 175 mm cranks & what I’ve noticed is my torque & power is outstanding, especially on climbs. I wished when I raced I would’ve used 175 mm cranks with the power & leg speed I had back then. I’m a 6 ft. 225 lb. cyclist who can beat my smaller cycling friends up most climbs here in So. California. Oh yes, I’m 55 yrs. old by the way.

[@eric_bones]

Thanks for making this! I've been debating whether or not to switch from my usual crank length with my new groupset, but now I think I'll probably just stick to what I'm already using. I think that one of the most important factors (and this has always been the case) is considering pedal strikes, which is really only an issue in specific scenarios anyway.

[@Durwood71]

Very well researched. What I got out of this video is that 170mm is the sweet spot for the majority of riders, and you should only go longer or shorter if you have a specific reason to.

[@rws0010]

The timing of this video couldn’t have been better for me thanks. I sized down one size on my new bike and kept the same crank length and discovered a new phenomenon for me - toe overlap. I may need to drop crank length if this toe overlap becomes a problem, but so far I can’t tell much difference otherwise.

[@Sator810]

Ryan Wayne I use a CX as a winter training and commute bike, that has terrible toe overlap. Changing to 165 was worth it just for minimizing the overlap. Still can’t use mudguards on the front wheel though, but that is less of an issue.

[@rws0010]

My bike is also a CX frame built into a gravel race bike. I am considering going to 170 mm from 175 mm to see if this eliminates the problem. Thanks for sharing your experience

[@aldude9511]

Just run a bunch of toe out to clear the tyre. I'm sure your knees will be fine. (joking of course)

[@bicyclist2]

I'm 5'11" and run 175mm cranks on my mountain bikes and 172.5 on my road bikes. I would like to try 180mm cranks to see if I can tell the difference. This was interesting. Thank you.

[@gregsimpson9391]

A good look at this! Regarding leg length relationship - its not really leg length that determines optimal crank length in my view but the length of the femur. So picture an engine pistons conrods and grankshaft. Thats the analogy. I was moved from 175 to 180s some 15 plus years ago by a very stute coach - ex TT specialist. It took a short time to re-establish my cadence mayber 3-4 weeks. So all of my road bikes including the TT have 180 cranks. I've never had an issue with cadence - did all my training at 95-105 - optimal power for me occured at 92-95 - for continuous power that is. As far as sprinting and track - no question - shorter cranks are better for short term power output. Sustained climbing and sustained power - i have never looked back on the move. I'm 1.89m and run a 58 top tube. Some smaller climbers use larger cranks - Pantani for example - he used 180s if I recall and he was tiny. Dont know the logic.

[@doug6669]

I have a 39" inseam and osteoarthritis. Switched from 175 to 200 mm cranks on my road bike 4 years ago. My ride has 1600 vertical feet of climbing and in spite of the 14% increase in mechanical advantage I was no faster (or slower). It was hard to spin in the beginning and avoiding pedal strikes was, and still is, challenging. My 200 mm IRD cranks are heavy but inexpensive compared to Zinn cranks. I keep using them in hopes they extend my knee life. Note this is the opposite of Jessica's approach below, where she switched to shorter cranks. Longer cranks increase mechanical advantage, shorter cranks decrease range of motion.

[@adamsteineke4661]

Just dropped to 165's from 175's after my bike fitter recommended it. I'm very happy with the change so far. I'm 6'1", so you'd think 175's would be ideal, however, arthritis in my hip causes hip flexion issues, so it made a HUGE difference to drop to smaller cranks. I only have 100 or so miles on the new cranks, but so far, so good. I'm way more comfortable on the bike after the adjustments were made. Can't believe I waited so long to get a proper fit.

[@masondanner6481]

Great video. I am 5'10" and just built a new bike with 160mm cranks. I went that short to resolve a biomechanical issue particular to the shape of my pelvis as diagnosed by my bike fitter/physical therapist. Despite good flexibility, can get palms to floor,II would get low back pain in even an endurance gravel position. For me, taking the chance, going that short, and opening up my hip angle made a huge difference.I can make more power, longer and more comfortably, in a more aero position then ever before. But I was comfortable giving it a shot because they studies say there is basically no risk in losing performance in going short. - my PT basically said the same as Dustin here. So I think one thing, is if you think there is a biomechanical advantage particular to your body, there is certainly no harm in going shorter. I ride a lot of gravel - and one nice thing about the short is all the pedal clearance. The only down side for me has been lack of selection. Rotor and Sugino are the only game in town that short with gravel gearing available, Favero Assioma pedals hacked with xpedo MTB pedal bodies for power.

[@kidagave1]

My girlfriend said crank length matters

[@kidagave1]

😝

[@NewEnglandDirtRoadie]

She told me it was girth

[@williambob111]

Yep, she told me that she likes my longer crank.

[@richardharris8538]

She's just messin' with ya, eh.

[@williambob111]

@@richardharris8538 lol

[@paulrobinson4987]

I will be glad to tell you my results and why I ended up sticking with this

[@event4216]

Thanks. Your findings match what I've learned as a kid, riding adult sized bike, pedalling through frame. What matters is - cranks shouldn't fall off BB spindle.

[@thegallery]

Hey Dylan, great stuff! I sat and lugged at a very slow cadence for years; like in the 70's. I virtually never stood, even in XC races. I also sat super high all the time, very far forward on my road TT saddle over top of the BB, as I could get super low with the dropper post when I got scared! But on Gerry Pflug's suggestion I moved from 175mm to 170mm. The different was huge! I found I could spin faster, stand more, and lower the seat as well. It didn't hurt as much to spin at a lower angle, something I could never do at 175mm. I also had more clearance. I think the only drawback is you end up raising your centre of gravity when standing, by about 2.5 mm,. I'm not dead sure on that, but it is because the pedal at the lowest point is a bit higher off the ground. All in all, the experience has always made me want to try a 165mm crank, but I never have! Even with the 170mm my cadence is slower than than everyone around me. I'm comfortable I think around 80rpm; but frankly just don't have a lot of data to know for sure as I never measured it racing.

[@briandewey5401]

Another reason track cyclists use 165,s is due to the banking on the track. With longer cranks you are more likely to strike a pedal and take yourself and riders below you down. Have been taken down due to that. That said not all tracks have the same bank angle.

[@farrier53]

Good vid ! A subject that's been re-hashed over & over but it is important! During the last 25 years I have tried every length in the book, made my own 180mm with D.A. Octolink, etc. MTB finally tought me that 175mm were the best for me. At 5'9" my imseam is almost 34". It'all about comfort level at the top of the stroke, bottom of the stroke is easy to deal with. Also, longer cranks are more manageable with relaxed seat tube angles (for me!).

[@The_CrackedPot_Christian]

I've had 150mm cranks, on a recumbent 'lowracer' style bike. Event shorter ones have been seen: I know one guy who has had 110mm. Short cranks are popular in recumbent racing. I'm 6ft tall and long legged, so I would be way out of the percent ratio for 'optimal' crank length. The short cranks on recumbents are preferred for following reasons: Cadence ('spin to win like Chris Froome) Aerodynamics: feet out front means turbulence will be less with shorter cranks Shorter cranks allows, in fully faired recumbents, a more compact nose to the machine, aiding airflow and thus aero efficiency. Muscle fatigue: faster cadence means lactic is taken away quicker. The trend with Pro cyclists from 30 years ago to today supports the idea that spinning is better than grinding. So faster cadence with shorter cranks might give indicate a marginal performance advantage. Some studies also indicate that the range of angle of knee/hip is the factor that makes the marginal difference in power output seen with shorter cranks.

[@kylecouture1917]

Thanks for making this. I have been wondering this for a while. In 5'7 with a 30 inch inseem and i use a 175mm. With that setup my max cadence is around 200 and I usually hold around 95-105 on my rides.

[@jehilario2659]

Seriously? We are similar height, only half inch taller and my inseem is 32.5 inches . I find it hard to pedal 170mm...

[@daryl4841]

At 200 cadence I think I'd be falling off the bike. With shortish legs and long cranks thats a crazy ammount of leg movement. If it works though thats what matters.

[@mjack96]

Thanks for this. I’m going to run 165s on my fixies and 165s on my mountain bike, because pedal strike is my greatest fear, and apparently it just doesn’t matter.

[@BA-PBXC]

One Note regarding crank length on the velodrome. The reason 165mm is max length people run is for safety reasons. Also often regulated as max length at tracks. It is set at this length to avoid pedal strikes when pulling up on the bank in the turns.

[@shewh0rn]

That last study is the one that prompted me to think about going from 172.5 to 165 mm (5'9" fwiw). As you mentioned, the evidence suggests there is no real difference in power output. From a fit standpoint the knee angles and hip angles are less acute. In addition cadence seems to naturally go up with shorter cranks and while I couldn't find any research that established causality (though there was some conjecture), it was a common observation across multiple studies. I'm not aware of any longitudinal studies that look at crank length over a period of say, 20 years to see if that has an impact on knee issues in (ahem) aging cyclists (I'm only 47, but my body has given me a few reasons to consider this more carefully given that I'd still like to be riding 23 years from now). Anyhow I figured If I dropped the crank size which resulted in a faster cadence the force on the joint for a given power output might be less (at that higher cadence) than it otherwise would be with a longer crank. While gearing is a part of that lever system, you do functionally lose some leverage in your smallest gear so to counteract that I'm also going from an 11-28 to an 11-30. So... new cranks, new cassette... also new shoes, and switching from Speedplay to Shimano DA SPD SL after 23 years (I have an appointment with my fitter soon). Be back in 20 years with an n=1 study that has absolutely no controls.

[@CeresOutpost]

Excellent video and just the primer I needed on crank length!

[@hangchengchen4493]

thanks for the science article review, it helps a lot ^^

[@FlyingPastilla]

Having 165 on my track bike, 170 on my commuter fixed-gear and 175 on my road bike I can say crank length matter a whole lot. I can reach 140+ rpm on my track bike out of the saddle and achieve my best speeds on it. 170s spins like a charm, not all over the place yet with good leverage without excessive foot speed. 175s feel off, my fit get all wrong and I get numb everywhere, cannot spin above 110rpm and I don't even feel like sprinting on it. The fits on all three bikes are very similar (with the track bike being the most aggressive with a long & low setup)

[@UMAGOLF]

Dylan, congrats for the brilliant research and thank you for sharing such a useful information !!!

[@gustavmeyrink_2.0]

3:37 the 20% rule tells me I should use 188mm cranks. The longest I could find was 181mm but they were a definite improvement in comfort over the 172.5 cranks I had before.

[@tqminnz1405]

I concur with the conclusion. I can feel a bike-fit difference between riding my gravel bike with 175 cranks and my road bike with 170 cranks and have been saving up to swap the gravel bike cranks to something smaller. When riding my XC with 175 cranks the bike-fit differences are not noticeable because the whole setup is completely different. Glad to learn that none of the crank length changes will actually have any meaningful impact on my measly power output.

[@Sator810]

There is a couple more things to be said about it. Going from 175 to 165, means you will have to raise your saddle by 10mm. Then there is the case of shorter cranks requiring less hip mobility when using aero bars. And less knee flexion. Both good for the long distances. But sitting higher is not ideal in my opinion.

[@GNX157]

Kai Barstad It’s okay, you gain an aero advantage being able to get lower over the bars which can be lowered. Also I think it would.

[@jg9008]

I've tried to educate myself about this topic multiple times and seemed to always find conflicting information. This video straightened it out for me, thank you!

[@L4ch74n]

My emtb is equipped with 165 and I think decreased chance of pedal strikes is 100% worth it. 175 with constant pedal strikes made me slower and less safe on my previous emtb. With 165 I can practically climb all stairs, rocks, roots without a worry

[@002rbanyai]

Exactly what I was looking for. Thank you!

[@csisticsakanyfeju1415]

Could you make a video about: the benefits of training/living at altitude and what difference does it make. ?

[@koenstrobbe8101]

After doing some research, i decided to put 165mm cranks on my bike to replace 172.5mm cranks. This makes a massive difference in bike fit. a 7.5mm difference in crank length opens up the hips by twice that at the top of the pedal stroke, in this case 1.5cm. I could also lower my handlebars a bit without losing comfort. As for power, every person has a naturally preferred pedal speed, being the speed by which the pedal travels along the pedaling circle. As a result, longer cranks will make you ride at a lower cadence, shorter cranks at a higher cadence to maintain the same pedal speed; since power is torque multiplied by angular velocity, the change in cadence (and as a result, angular velocity) and crank length sort of cancel eachother out. in other words, power might vary, but really not that much. The right crank length for each indivdual's biomechanics trumps that by far.

[@hemi265mustard]

Power and crank lenght and small power percentage is 1 thing, but comfort and getting the right position to hold that power for extended time is another. Im 5 ft 6 and with 170mm cranks and correct bike fit i still seem to get a sore lower back. But with 165mm cranks zero issues. Saddle hieght measurement is taken from centre of pedal bolt hole, not BB.

[@andrewrivera4029]

Yes, I went from 175mm to 170mm crank on my mtn bike and I find about 80% less peddle bang on rocks and I can stand and peddle so much better. I’m 5’ 10” and my inseam is 32”. The only thing I noticed was a bit more narrow stance took a little bit to get used to hitting jumps.

[@WatSail]

1:43 Good to see Bike Fit James.

[@chrisprice6206]

Dylan, a cyclist ought to use the shortest crank that is comfortable and allows the best range use of gears. from 172.5 to 160 the top end speed in the saddle changes. solving/designing for smallest chainring And smallest cassette is the major point aside from comfort. so when you go to sprint, the cadence can go up and "CE" can rank well. source: i saw an old man on a singlespeed ti do some amazing things and it had to do with his crank arm and gear choice; his [gear]"range"(sic) was astonishing. we have all seen this.

[@Southerncyclist]

Im 6'3 my in-seem is 35'3/4. I run a 180mm crank arm length. I have run 175mm and still have 177.5 on my trainer bike. Personally I prefer the length. My Average cadence on rides is about 84. I try too keep it at 90 plus. I want go any longer though. There are charts online that give a great ideal crank lengths to in-seem length. Whish I could post that. 177.5 is probably my ideal length and 180 is at the top of my range. Different size bikes should come with different size crank arms more than just 3 sizes with a 5 m difference 170,172.5,175. To get real power out put comparing crank arm length you need to test the same gear selection. Then measure power at the wheel.

[@cycleslarrivee2471]

Did you find anything about ultra endurance? I heard going shorter reduces the movement in your hips therefore reducing potential problems in 1000+ km races. Is there any basis to this statement? Cheers mate!

[@nwimpney]

It also increases the force at a given cadence and power output, (or increases the required cadence at the same force and power output) so there's no free lunch. If you're moving your hips more than is comfortable for long rides, shorter cranks might help. If you've got long legs and you're already underusing your comfortable range of motion, you're going to be increasing force on your knees, or increasing your cadence to maintain the same power, so you might make things worse. It's really about fit, and unfortunately it's not something that can be easily adjusted, so there's no way to experiment cheaply, so most of us are stuck running whatever comes with our bikes, whether it's ideal or not.

[@AdamHansenOfficial]

Using the SRM formula to work out its slope uses crank length its less force required with a longer crank. So in that sense if you have a bike fit for a longer crank and have that range of movement is fine it would be more beneficial in ultra-endurance events

[@BrusselsBlog]

Track cyclists also run shorter cranks because the rules of the velodrome often specify them (along with BB height) - the reason being to avoid pedal strikes when riding slowly on the steep banking... the fact that it lets you get your torso lower and pedal faster are happy byproducts :)

[@red00tl]

As always, I agree with the Backward Cap Dylan! :D But, jokes aside, I also agree with your final comment that crank length should be considered more from the bike fit perspective. Any 40-something with a pronounced beer gut would appreciate shorter cranks for opening up the hip angle and preventing the knee from kicking into the belly. ;)

[@derekbiggerstaff]

Track riders use shorter cranks to avoid grounding the right side pedal on the banking when going relatively slowly. To avoid damage to the track velodromes have a maximum length specified.

[@GordoGambler]

With deFailleurs, you just won't notice for sure. Mine all had 165s, they always felt lame to me. Before internet, I just had no clue about using different stuff. I am 5'8" with about 810 mm standover. Mostly I rode 58cm bikes, a tight fit. I put 180s on my custom tour bike, because that's what my antique SS Rudge had. After a slow acceleration, I just float along easy as pie. About 75 rpm at 16 mph. When I got a SA 5w, it had 165s for the first 3 rides. Then with the 180s, the 9% increase in power moved the shift point 1 mph and made hills way easier. The way I see it, I need to push down 9% less for the same speed, while a shorter crank guy needs 9% more RPM. Funny thing is, we both go the same foot speed along our different circumferences. Just like with my SA 3 going from 46/18 to 46/19. The shift moved from 14 to 10 mph. Huge difference. These cranks are 1 piece 167mm. This CCM bike is 30 lbs lighter, but 2 mph slower. WTF?? It has brand new 650B wheels.

[@tubbytoast2]

Fantastic !!! Best 10 minutes yet , BHD take note 🙂 !! I think originally track rides used 165 mm so that didn't hit the pedal on the banking , and 175 on MTBs was because they thought u needed extra leverage to smash up the short super steep climbs

[@lourensrudman4614]

Just a note on the track crank length, it’s got a lot to do with the banking, the very steep tracks you need it.

[@edubfromktown]

Awesome video Dylan. Some of my riding cronies are obsessed with crank length and wholesale swapped out a bunch at the same time. Kina had me thinking it was vendor conspiracy to get people throwing away perfectly good stuff for something "new & improved" LOL I've never paid much attention to using anything other than 175mm on all my rides. I messed with 180mm's on single speed 29er's and found that it felt more efficient on certain geometry bikes over others. Nothing too dramatic and with the more modern geometry designs with lower BB height, longer cranks can lead to more pedal strikes.

[@rogerd9405]

Thank you! I've been trying to find info on this subject after a few friends swore that dropping down to 170s made a world of difference to them. I didn't want to spend the money on new ceramics to find out if if it's all in their head or not.

[@redjalapeno5714]

After running 165 on my track bike and 170 on my other rigs, switching to 175 was soooo crazy at first. I felt like my legs were flinging off my body! However, switching to 175 was necessitated by moving to the Appalachian mountains. My spin is just slower (rare to go over 160 rpm) and having that extra length has seemingly helped me with the miles long 4-6% climbs. Plus I'm 56 now, and I don't do anything fast, just longer. The longer length seems to help, but that could just be the placebo effect.

[@em1355]

Great video! Information was very helpful as I was thinking of changing my crank from 170 to 175, as my intent is to use my MT bike more as a cross-country bike (i.e., riding more on non-technical trails), as I was thinking that this would help increase my pedal efficiency. I am 6'2" and prefer riding through the woods on long trails, but still have the bike to handle any bumpy type single trail, but was concerned that if I went to a 175 that this would increase the chances of a pedal strike. Most likely will stick to 170. Thanks again for the great video!

[@BlackWaterCyclist]

Great info. Bingo, just ride what feels the most comfortable and will help you ride more. I've done a lot of research on this in the past. I've tried 190mm down to 160mm. I found I preferred 170mm. I am 6'1. You're going to get heckled by Durian Rider now, "spin it to win it!" LOL. Thanks again Dylan.

[@marcdaniels9079]

Black Water Cyclist Heckling from Durian Rider is a badge of honour! 🤣

[@kylecouture1917]

Im 5'7 and use 175. Thats what came on my bike but it feels good. And i dont think i would notice a difference with a 172.5 or 170 tbh.

[@moviepedro]

I ride a 170 on my road bike and im 6'0. one of my track bikes came with 175mm (used) but I switched to my normal 165 track crank lengths and I noticed a slight difference in feel, but its hard to describe and not that noticeable, I guess more favoring to spinning like the video says

[@nwimpney]

I'm 6'4 and have a 1000mm inseam. I've been most comfortable riding the 180mm cranks I have on my bike now. I found I get sore knees when I ride fast for a long time on the 175mm I had on it previously. The 165mm on my track bike are even worse. I want to try longer, but unfortunately there aren't many options in that regard.

[@BlackWaterCyclist]

@@nwimpney Oh yeah, you will probably feel better on longer cranks. There is so much that goes into crank arm length besides just femur length or inseam length. Those are important measurements but I think other things that people do not think about is if you are a toe down vs heel down vs neutral foot peddler. If your toe down like me, your hip gets closed up more at the top of the stroke which is why I like the shorter cranks. While someone who he is heel down is able to make that "deadspot" not push up their hip as high. Another thing is hip flexibility. If you are tight in your hips, you will like shorter cranks vs someone who is more flexible. I had some 190mm lightnings I tried. I could mash up some crazy steep hills but it was essentially the same as putting a 34T or 36T on the rear cassette with a 170mm crankset up front. I had a little bit of front knee pain when I went down to 160mm. Were you raising your saddle and moving your saddle setback rearward when you tried the shorter cranks?

[@simonalexandercritchley439]

Watched this back in 2020 and again today.I have just used what came with the bike,170 (now indoor bike) 172,5 road bikes,175 mtb & TT bike. Only slight difference I can feel between each,but for low cadence mtb climbs (XC) 175 feels better. I am 5 10" /178cm inseem 34'/88cm. I am not a sprinter.Tried shorter cranks on road did not see improvement. Maybe try 170 on TT next. Regarding track: don't forget they are running fixed gearing and need clearance on the banking,even tall riders use short cranks,it is not just for the sprinting/high cadence.

[@peabody3000]

i'm around 5'11 and switching from 165 to 175mm cranks wound up somehow being an amazing upgrade for me.. so much more comfortable. i think that extra comfort def comes into play on longer rides, but either way the data in this well-researched vid was actually pretty shocking

[@ernestoechevers4741]

Use the crank length to get more comfortable on the bike and to help maintain your aero position on the drops for longer periods with no struggle to breathe or stress your back etc...

[@garethnorwood7596]

Something that didn't come up in your video, is that having longer cranks allows you to marginally ( up to 10 cm) lower your center of gravity on the bike, similar to lowering the BB, which can help with stability & high speed cornering, assuming this doesn't compromise your ground clearance on rough terrain. This may provide a greater perceived difference than measurable one... The other thing it can help with is fit on a frame that has a long or short head tube, when you are trying to find the right bar height to work with your correct saddle height. Lengthening or shortening your cranks will allow you to raise or drop your relative saddle height by +/- 10cm to find a good balance with the stack height of your frame for the front end.

[@tonyabruzzio7399]

Thank You. Good research. I’ve been running 175mm for years (32” inseam) on bikes around 56cm. Now that I am an old man, and In the market for new road bike, I am looking at 172.5mm as it seems my knees are getting a bit sore on rides where I am pushing more power. I was worried about going down to the smaller crank length, but this video tells me - it!’s no big deal for 2.5mm delta.

[@WildMidwest1]

While this is a terrific video, it barely touches on the main point for recreational mountain bikers: safety. Most of us don’t care about power optimization or fastest trail times so much as completing the ride without a spinal fracture, shoulder dislocation, hip fracture, or head injury. I replaced my 175 SRAM Eagle GX cranks with 165 mm cranks on my 2021 Santa Cruz Tallboy a month ago. I notice no difference in power output and only a slight incesse in my cadence. On pavement the benefits are minimal, however on narrow / sandy SoCal trails my confidence with sharp switchbacks and steep inclines is much greater. Pedal strikes during off-camber hairpins with 70 degree rocky drop-offs are terrifying; it’s a constant risk with the hillside inches away and frequent small mudslides or stray rocks. I have no regrets with my shorter cranks. They’re a major safety benefit here in SoCal. At $150 they are an excellent value compared with the ambulance ride, orthopedic surgery, neurosurgery or months of rehab.

[@hebijirik]

Great video. This is going outside of the scope of it but here is a perhaps interesting personal observation: I experimented with cranks from 153mm to 175mm. On an upright bikes which I ride with just flat pedals I like 170mm the best. On recumbent bikes which I ride only with clipless pedals I like 160mm cranks and weirdly they feel the same as 170mm on an upright. Compared to 170mm knee pain after very long rides is less likely with 160mm - on a recumbent, I cannot do a long ride on an upright. I think that on upright bike you have more pelvis movement available and you want to stand up sometimes using more force and less rpm (therefore longer cranks), while on a recumbent just spinning faster is the best way to make more power (therefore shorter cranks). Maybe this is why different length feels comfortable.

[@doughicks8048]

Hardly a child on a kid's bike, I use 150s, but there are multiple reasons. Firstly I have short legs, but after breaking my hip and being left with scar tissue right where my hip hinges forward I couldn't get my leg over the 10 to 2 position without actually swaying my upper body. I found a site that did the research, (bikedynamics.org) on leg length and crank length and my numbers, without injury should be 153. Just the same I was skeptical and tried a slight drop of 167.5s. Better but still a dead spot at the top, then 160s which I was happy with and ran for a good year before getting a TT bike and thinking I'd try 150s on it to get more aero. Well I like them so much I run them all the time. Given my experience I would say there are a LOT of people running too long of cranks.

[@LarsRR]

While I can‘t underpin my findings by actual data, I figured out for myself, that a short crank fits me better. As a tall rider (6‘2.5“) all stock bikes I get are usually equipped with a 175mm crank. However, a a 170mm feels much better for me, as I am better with higher cadence. That’s why I ride 170mm on my roadbike and 165mm on my TT Bike. Always bare in mind that these are differences in the area of 1/10th of an inch, so the effect on torque is also minimal.

[@lukeschmidtaa]

For Track Sprint it's an interesting one, because you have to account for the reduction in gears with the same leg speed "rpm". Standing starts are better with a longer crank (higher moment), and shorter cranks are generally seen as better for spinning once at speed.

[@mikefule]

Crank length is crucial to an efficient pedalling action. Serious distance, speed or cross country unicyclists have only crank length, wheel diameter and tyre section to vary, and cranks are the easiest to change. We use cranks from around 75mm right up to around 170mm. Short cranks means faster cadence but reduced torque; longer cranks means increased torque but reduced cadence. The ideal crank length for any individual depends on the length and ratio of their leg bones and a number of other variables such as fitness, preferred riding style etc. If you don't believe crank length matters, then consider two extremes: cranks of 10 mm, and cranks of 300 mm. Either would be virtually unrideable. Empirical experience shows that somewhere between 150 mm and 110 mm is best for general riding most unicyclists. However, a unicycle is low geared (direct drive to a wheel typically between about 20 inch and 36 inch) so requires low torque. For a bicycle, somewhere around 150 mm to 175 mm is probably ideal. Clearly a 1.6 metre adult and a 2 metre adult would not find the same length ideal. However, the industry sells us a smal selection of standard lengths because it is easier for them, and it's what we're used to.