Are 145mm Cranks The Future? | Testing Crank Lengths With Neko Mulally

[@bibasik7]

A wild Seth appearance is always appreciated

[@brettrosenbauer3299]

Yes! Nice to see. For short cranks (under $200.00) Trailcraft Cycles has has 140mm, 152mm, 165mm cranks being run my pro downhill riders.

[@IOUaUsername]

@@brettrosenbauer3299 Or pick up a Giant Veer 20 for $50 on marketplace and rob the cranks. They're steel so even though they're made for kids I trust them.

[@brauljo]

I'm hella surprised they didn't mention him in the video title.

[@hardtailparty]

Wonderful video. This just goes to further reinforce why sizing bikes by height is an oversimplified way to look at it.

[@EarlLewis]

Bike companies really need to wake up to real world sizing for the humans that they sell to. The SML sizing model is dead.

[@stevez3041]

I was going to put in a shout out to hardtail party for bringing this up and for doing an awesome video that I hope everyone watches also! Such great content we have in the modern Era of mtb and KZbin!

[@arandomJohn]

Everyone should check out your video on the topic. You've been big on this for a long time.

[@oscarwitvliet9139]

Your video was great. 175 was not good for my body i now have 165mm cranks . So thanks Steve .

[@darlafitzpatrick8770]

I'm 5' 4" and my women's-specific Trek trail bike came with 175mm cranks, which should be a crime! I just switched to 155mm a couple months ago. Bought mine from Appleman Bikes in Minnesota. Matt Appleman has good data on his site showing that tibia length tends to give a more accurate estimate than inseam

[@ebl11111]

Thank you for letting me know about Appleman's cranks. I definately would've considered those if i was aware of their existance when i was shopping around. Ended up fitting 152mm's from Trailcraft. Best upgrade i've ever done. Like day and night. Super difference in the way the bike performs on tricky passages on the trail

[@ebl11111]

Question: Do you know if the appleman spindle is made of steel or aluminium?

[@uldi1s]

Just went to check my length to Appleman Bikes and it said 197.8! 😁 Now I understand why I'm so comfy with 190's 😎 But only in my BMX bike. On my MTB I just run whatever strong 175's I can find

[@John-dh1gh]

I'm really surprised this isn't quite a big thing in cycling. Seat height is ok for inside leg adjustment, but the lower limb length turning circle is obvious. Shorter lower leg, shorter crank.

[@MrSponjaBob]

Thank you very much for this comment, I found the two websites that explain everything. It has been very helpful since I have not been able to get rid of a pain that I believe would have become chronic if I hadn't read all this information. Unfortunately, I already spent my money on cranksets that are not very good for me, but there's nothing like investing in health and, above all, to continue enjoying cycling, which is what I love most in this world, for many more years to come. Thanks to @darlafitzpatrick8770, @GMBN Tech for always being there with their great library of tireless information, Matt Appleman and Steve Hogg.

[@rule3036]

Hardtail party did a really good crank length testing/ discussion some time ago. Worth checking it out.

[@donbenincasa7442]

I’m just over 6’ tall, and I’ve ridden 175 to 155 and there is a huge difference…I’ve landed on 160mm (5 DEV) 🎉

[@renzoguillen1]

I´m 6.3´ and I ride 175mm cranks... I was thinking to get some smaller ones for better clearance

[@LemonySnicket-EUC]

What is your inseam measurement?

[@piotr2951]

I'm 6’ tall and went whit 155. Just went with Pinned instead of those hyped up expensive cranks

[@danielmasset4153]

...if you don't mind me asking what is your inseam length...I'm just a fraction over 6' with a 34 inch inseam...I'm riding 175 cranks now and am thinking about 165 depending on what your inseam is...tia...

[@ronbeardsley5961]

We need a chart for those of us with no crotch-o-meter 🤔🤷‍♂️

[@andynelson1977]

There's crotch-o-meters appearing in lots of shops now!

[@placesucantgoadv2579]

Applemanbicyles has a converter on their site and offer multi position rental cranks

[@robbybobbyhobbies]

Found a few online calculators by searching for “crank length calculator” (rocket science mode engaged :) )

[@brokenrecord3523]

@@andynelson1977 Yes, but it is obviously a calculation based on inseam. What is the formula!

[@pobthecat]

Hi Guys, what I didn't hear much about in the video is the leverage aspects of the cranks. Going longer gives you more leverage on the climbs, but shorter usually gives you more use of your gear ratios. An extra 10mm crank length can equal +/-2 or three teeth on the cassette.

[@Morpheas001]

Let's ask the BMX guys what's better for putting power down

[@bigredactionsportsstuff1245]

Technically it’s more leverage, but putting power down is about more than just leverage, it comes down to body angles and other individual factors.

[@IthacaDon]

Harder to climb with shorter cranks until you change to a smaller front sprocket.

[@antc5010]

I agree entirely. I've just made the jump from 26 to 29'er, 3x9 to 1x12 and 175 to 170 cranks. The maths showed hill climbing should be harder on the 29'er, but I haven't felt it. Body lever sizes matched to bike crank length is far more important than the tiny loss in pedal lever length as you can extract more power from your legs with the proper fit. @@bigredactionsportsstuff1245

[@Frater_Maven]

Like with all things and mountain biking it's a trade-off. In my opinion the little amount of added difficulty on ttclimbs that come with shorter cranks is really only noticeable immediately after you switch and about 10 rides in you won't even notice it, however you will notice every time you ride your bike for the rest of your life how much pedal strikes have gone down and frequency and how that old notion of dropping the outside foot on every turn becomes more and more dated and unnecessary

[@DynamiteLanding]

I just purchased a new Rocky Mountain Element in XS for my 9 year old daughter who is 4’8” tall. It came with 175mm cranks. Crazy. Went with 140 and it’s night and day difference. She had trouble riding it stock.

[@weepingBear]

Best video by far for proving crank length matter! I love the guests! It makes it more real! Seth & Bobo woohoo!!!! Great job GMBN!

[@c0nsci0usness]

Another thing no one considers is Q factor. At 6'2" I'd love to run a wider Q than is available.

[@Morpheas001]

​@@c0nsci0usnessI'm also 6'2", but I'd like a narrower quack- factor myself. Things get in the way quickly, though.

[@JonasKastebo]

This doesn't prove anything its two people in a commercial for 5dev that have a money incentive to say thing that are positive for a company that sell cranks of different lengths. It is possible that everybody should have shorter cranks but this is no proof of anything. It was the same with all the youtubers raving about oval charings making you more efficient because they could feel the pedaling was smoother. Not to say that their isn't any upsides i just don't know if there are any except for larger groundclearance for shorter cranks.

[@brauljo]

Wait, ¿Bobo isn't just someone who works at GMBN?

[@Morpheas001]

@@brauljo Bobo has his own yt channel

[@geoffcorvera8998]

I’m 5’3” with short-ish legs and have been struggling with long cranks all my life. The smallest crank I’ve found available at my local bike shops are 165mm. I would love to try 145mm cranks on my mtb for some downhill, maybe even bike packing, and my gravel bike since a hip injury has been causing me pain at the top of my pedal stroke.

[@davegee124]

the smaller the crank the less stress on your knees and hips,win win.

[@ivanshevy]

Like for the Burm Peak host

[@wordreet]

Shirley "the correct length" cranks for each individual should be the future!

[@KevinT3141]

Agreed, but did anyone else hear Leslie Nielson in their head after reading this comment?

[@wordreet]

@@KevinT3141 What you're supposed to say is, "Yes it is, and don't call me Shirley!" 😉

[@justinfournier1285]

Great way to sell more parts.

[@KevinT3141]

@@wordreet That surely would have been the thing to say.

[@wordreet]

@@KevinT3141 Shirley you are surely right!

[@rogerd9405]

Bikes should be spec'd something like: XL-175, L-170, M-165, SM-160, XS-155 or at least start playing around with different lengths for different sized bikes. I mean the industry changed wheel sizes just to break from tradition. So why is it taking them so long to wake up to this when people are actually asking for it?

[@BIKINGWITHBOBO]

Those are some sa’weet cranks!

[@richardpayne5176]

😂😂😂 good times with the crotch’o’meter dude

[@BIKINGWITHBOBO]

@@richardpayne5176 lol, indeed 🍆

[@terb5804]

I'm sticking with 175s and it's the best decision I've ever made!!

[@brianbass4971]

I can’t believe frame manufacturers are still spec’ing 170mm cranks on XS and S frames. I have had to pay for 165mm cranks on all my bikes at 5’6”. Now I’m thinking that even 165’s may be too long.

[@ThunderStruckMTB]

Make sure you raise your saddle height accordingly when going from 175s to 155s which will raise your center of gravity and might require a cockpit adjustment as well...

[@CJinsoo]

i was getting excited about changing crank size but then this thought occurred to me. since my frame size is constant, i’ll have to raise the saddle and possibly get my bars higher, too. those would be huge changes all at once. could be tough to adapt.

[@msm624]

Why would you raise your saddle with shorter cranks?

[@ThunderStruckMTB]

@@msm624 Because the crank is shorter?? If you are a rider who knows your seat height number and are sensitive to any changes then you know. If you're a rider who raises and lowers their ridged seat post and never gives saddle height a second thought as it's close enough, then you will be fine.

[@CJinsoo]

@@msm624 to get full leg extension when you pedal. If I lover my dropper post, even an inch, I know longer et the full leg extension when pedaling. About 25mm=1 inch., so if you go from 170 to 165, not much change, but I'd still notice it. if you went to 145, that is a huge change. It is still peronal preference, but riders who are at full leg extension now, are very likely to need to adjust. If you don't care about pedaling--note the emphasis on E-Bikes driving this in the video--then may not matter to you.

[@msm624]

@@CJinsoo shorter cranks effectively raise the saddle, you'd need to lower it

[@bmaclaps]

Damnit! If I would have known Anna was in town I would have asked her out to a steak dinner.

[@KiwiInGermanyMTB]

If 5dev sold their alu cranks for a price that wasn't for multi millionaires I'd love to try shorter cranks. There aren't many options at the moment without changing a lot of parts

[@ebl11111]

Actually, there are cheaper ones out there. You just have to make an effort to search for them since SRAM/SHIMANO still don't see any money in this (well SRAM has 155 on their NX series but only for OEM-sales on complete bikes, but if somebody with 460000 subscribers would put some pressure on them... hello @GMBNTech it could easily happen

[@LaurenceGough]

@@ebl11111 Any more tips or hints as I am after shorter ones but it's hard to find for the non millionaires.... Any part numbers or brands? Thank you

[@LaurenceGough]

100% agreed fabsmf, did you manage to find any? DUB compatible ones ideally...

[@qwerty6789x]

Us Asians Averages 5'5 Height yet the only available Crank here being sold for decades are 170s. its either gate keeping or intentionally complimenting our natural huge calves.

[@nathantoney.1501]

Weight weenieism and road bike theory needs to go away

[@axelsimonsson3032]

I want short cranks because I’m q really short rider and like a playful bike

[@rogerd9405]

It's about time! I've been asking GMBN to do an in depth review on crank lengths for years. Every time I got the generic answer, "The longer the crank the more torque. Shorter cranks less torque". Never addressing fitment, inseam length and spin.

[@ebl11111]

Yes one gets tired of that generic bullshit answer from everybody. Even this video doesn't cover everything it's better than nothing. It's good that people is waking up. Lets hope they influence SRAM to release their cheap OEM-only 155mm NX cranks for sale to everybody!

[@rogerd9405]

I've always thought it was ridiculous that all bikes came spec"d with 175mm cranks, no matter the size of the bike. I mean, bike manufacturers played around with different wheel sizes for different sized bikes but still spec'd 175mm cranks on a small.

[@Dwyane1st]

obviously, using inseam length should be a much more accurate measure (than body height) when deciding crank length. Now I wonder because everyone's different, even two people with the same inseam length could have wildly different lengths in their thighs and shins, would that affect the pedaling kinematics and therefore crank length? #askgmbntech

[@ebl11111]

41% of tibia length is a better way to measure

[@Dwyane1st]

@@ebl11111 can't really tell if you're being serious or not

[@lambo79]

Where do u buy the 150-155?

[@NomadHatch]

Super glad we're finally having this conversation! Can't wait til 155mm are widely available and not just custom machined billet options!

[@bearjewmtb4827]

6’2” and run 155 on all my bikes now. Absolutely love it.

[@LEGENDofBEANY]

Oh wow! What is it you like about it?

[@vadymvv]

I did install 152mm cranks after 175mm, my height is 5'6. I wish I go for a golden middle like 165mm or 160mm, because I feel like power isn't there when you use your weight to pedal. On 175mm I could gain speed faster, than on 152mm cranks. Positives are more natural position for me.

[@sixty2612]

I always ride XL bikes (6’2” with short torso and long legs) so always had 175mm. My new Stumpjumper (S5) came with 170 and I love it. I don’t notice any difference other than less pedal strikes on tech climbs. Don’t think I could go much shorter though, I have the OneUp 240mm dropper and it’s still quite a ways above the frame cause my legs are so long.

[@tehalexy]

long legs with 240mm dropper here, im at 165 cranks and I hate pedal strikes :D

[@rastokandra]

I am 5.6 and I use 170mm cranks. I feel the loss of torque even from 175 to 170 . I can't imagine using anything shorter than 170

[@MrMatthias03]

HOLY SMOKES!!! BOBO and SETH!!! Rock on GMBN, thanks for bringing the pros out! 😄

[@H3avyHaul3r]

so after riding with 170mm cranks for the last 20yrs….purchased my first ebike (with 165mm cranks) in February and with multiple rock strikes i dived into shorter cranks for it….went straight to some 150mm Mirandas and love the freedom of being able to pedal through all terrain without fear…just wish Shimano/SRAM would catch up, it’s not a trend big $’s….

[@BryanHoefer]

Bobo's section with the crotch o meter made me spit coffee out of my nose. !

[@marcopaganotto9125]

Honestly, as an old man, coming from a time where you only had one crank size, anything shorter than 175mm is immediately noticeable to me. I find that even 10mm shorter requires more effort to turn. Thinking about it, surely more force is required to push a shorter lever right?

[@Thedoug369]

145s? I'm 6'6 and I have to use 175s or pedaling standing wrecks my knees.

[@paulharrison75]

For a shortarse like me combined with the low BB of modern bikes it seems like a no brainer.

[@ivan_di_dio97]

I want this crank because i need short crank to have correct alignment of the kneecap and pedal axle. I would also greatly reduce the risk of hitting the ground

[@dennis6088]

So how do you measure your crank lenth without the croch o meter?

[@coolcycles]

Take a folding ruler and book to measure your inseam. Crank length is around 20% of it. Some people have aspecially long thighs and short shinbones, leading to a bit longer cranks, or vice versa.

[@troyesch6203]

They should be able to tell you what size crank is best for you based on your inseam. I did find a website that did just that and my inseam is 32 inches and they said the optimal crank length for me was 165.

[@mikerobertson9787]

I took my first ride on my new bike just today with Canfield Cranks. They also recommend shorter cranks as well, with a formula based on your inseam They recommended 155mm cranks. I went with 160mm, and wow! What a difference! Love it!

[@mariogomes8688]

What is the formula ?

[@mikerobertson9787]

20% to 20.5% of inseam

[@michaelmann3636]

All I know is I’m 6’-3” with a 34” inseam and have ridden 175 or longer cranks my whole life until I bought a Transition that came with 165 on it. They felt so natural and good, my hips and legs were less sore after a ride, less pedal strikes, more stability and able to rev the bike up faster etc.. Now all my bikes have 165 on them and I will never go back to longer.

[@olik136]

is 165mm not the most common size? I am pretty sure that every bike I ever had came with 165 cranks? maybe there are regional differences??

[@LazarusButtons]

​175mm was very common for medium to large frames in the US. I'm a bit taller, but every bike I've owned (road, gravel/cross, MTB), 1980s-2010s came with 175mm stock. @@olik136

[@cheesywheels]

@@olik136I think the most common sizes are 165 to 175. Thanks bike industry...

[@DannyC3636]

​@@olik136usually come 170mm

[@michaelmann3636]

@@olik136 most bikes in size xl used to come with 175 until this modern era, at least in the US anyway. (Transition) was the first

[@pwiles1968]

I dropped my cranks fron the stock 165 to 150 on my eBike, more for pedal strikes but i noticed the difference in riding almost immediately would never go back to longer cranks.

[@kacmarcik23]

I’d love to give my girlfriend these cranks. She’s four foot nine with short legs. She’s rock strikes everything on 160mm cranks so have these super short ones would be great.

[@truckymctruckerton]

155mm 5devs on an ep8, perfect length (till 150mm ti units come out...) for the rocky terrain up here.

[@endianAphones]

You need a Hardtail Party Steve cameo. I tend to put 165 on all my bikes because it's the smallest available. However it would be interesting to see this in practice on something like a XC circuit, and measuring power etc.

[@maverick5695]

#askgmbntech #gmbntech #gmbn hi there, i enjoyed this video, having seen one from gmb regarding crank length a couple of years back. having suffered with lower back / hip issues and redone bike fit the only other option was to look at changing crank length. i run a single 44t shimano chainring on shimano hollowtech ii slx crankset - the cranks are 175mm (stupidly no other length was available at the time.) not having a massive budget the only alternative i found was complete crankset at 170mm (nowt shorter) and i had to adjust saddle height, fore & aft and some aspects of cockpit to accommodate. i could still do with going a bit shorter with cranks maybe 160mm, have seen some hollowtech cranksets with arms at various lengths, described as being for kids or folding bikes but they are gxp so i'd have to change chainrings too! gxp chainrings appear to be described with varying degrees of angle offset, what does this offset do - does it just reduce or increase the chainline, which i have at 53mm with current setup?!

[@WheelsAndHelmets]

How are the shorter cranks with climbing? I do love to climb.. but maybe it's because i suck at shredding 😂

[@shendoyafuso7041]

surely my 25” inseam is better suited on something shorter that 175mm cranks 😅

[@tomquimby8669]

Take away is Anna is a smoother rider, nice flow in control.

[@KurtisPape]

I met Seth once and i'm a similar height, just a bit taller and all my medium bikes came with 175mm cranks, it's a bit ridiculous really. I built up a gravel bike with 172.5mm but I wish I tried 165mm cranks.

[@nathantoney.1501]

Been running 150s on the ebike and 155 on regular mtb bike for 5 years

[@MrDino27]

My Scott Ransom came with 175 .I switched to a 165 gx wow the difference is amazing with 170mm of travel front and rear .I can now peddle in corners and out of corners .

[@brauljo]

3:26 Not only is it an unannounced Seth appearance, we get to learn his surname.

[@Dlawler]

Im 5'6" and recently gone to 165mm cranks and an oval chainring. And those two things combined have been a night and day improvement for me

[@LemonySnicket-EUC]

Inseam measurement?

[@Dlawler]

@LemonySnicket-EUC its around 31-32"

[@LemonySnicket-EUC]

@@Dlawler I'm 6 ft with the same inseam. The inseam measurement is paramount.

[@Dlawler]

@LemonySnicket-EUC it's funny how all that works. I allway question my own memory when someone points it out

[@DaBinChe]

I been using 155mm cranks this whole summer and really like them. Inseams is 30" with no shoes.

[@actionong]

What is your tibia length. What's the sensation difference you feel? Is it more comfortable?

[@DaBinChe]

@@actionong Not sure about tibia length but a tailor once told me while he was measuring me for a motorcycle leather suit said that my thigh upper leg length is longer than the average man my height. So my lower leg is shorter than the average man my height. My trail bike is 155mm cranks while my Enduro is 165mm crank. This is mainly cause 165mm is available while 155mmm is not common. I got it to try it out and really am liking the 155mm. I actually can barely tell the difference between the two...could be cause of different bikes and different gearing. Both feels pretty comfortable and I can barely notice the longer 165mm. I mainly like the shorter cranks to reduce pedal strikes...But I can tell a difference between a 175mm, 170mm and 165mm. Ergonomically I much prefer the 165mm over the other two longer ones.

[@darrinkulyk9560]

20 % Of your Inseam for those without the Device

[@WesMacaulay]

MTB kinematics have plateaued in the last few years, so seeing some attention paid to ergonomics is actually brilliant.

[@EarlLewis]

And long overdue...

[@ixcel83]

I rode 175mm forever thinking it was the best way to get leverage. I went to 170mm on one of my hardtail bikes and it felt really good. I tried 165mm on my all mountain full suspension and it felt amazing I do not think i would like the shorter cranks as much on the hardtail. I would love to get my wife on some 150-155 cranks. Her size small bike came with 170mm. Canfield makes shorter cranks and I believe Heir does for kids? Nice job with the video. I love that you guys collaberated with so many people when you were in the states!

I was wondering about leverage as well? How did your shorter crank affect your power transfer from legs to wheels during climbs or sprints?

[@ixcel83]

@ I found spinning to be better. For hard climbs you can tell the difference the power stroke feels shorter, I wonder if an oval chainring would be beneficial. It is recomendad to drop chainring size to compensate for shorter cranks. Sprinting is fine.

[@mtbsc016]

#ASKGMBNTECH what did ya'll think of Kanuga bike park? It is my local bike park and is was wondering how it compared to all the trails you have ridden across the world?

[@mikeriley1475]

Now i want to try the crotch-o-meter to see if i should try shorter cranks. Also, lol @Bobo.

[@TenaTenci]

Short cranks are king

[@cameronwheler7367]

Would've been interesting to understand the logic on how the measuring device works. IE what inseam relates to what length. I'm 6'5" with a 37.5" inseam with shoes on. Riding the stock 175mm cranks that came on my Stumpy Evo S6.

[@williamyawn2325]

ahhh so sad I missed yall visiting my neck of the woods.

[@WilliamBalsham]

Switching to a shorter crank will lower the power you can generate at the wheel, all else being equal. If you shorten the crank, you would need to switch to a smaller chainring to get back to a similar power, which will in turn have an impact on the top end speed in smaller gears. The drivetrain is a system, and changes to one part sometimes require compensating changes to other parts. It would be a great follow-up video to talk about the relationship between crank length and chainring size (and cassette, and even back wheel size for folks who switch to mullet)

[@justsayin3600]

On a full suspension bike carrying a heavy rider with 175/170 cranks are too long. It doesn't matter if the margins of torque are a fraction higher if someone has to to pump up the rear to an uncomfortable ride just to keep from pedal striking. All a shorter crank will do is make you a stronger rider at the end of the day. On downhill and enduro riding it's the same thing, pedal strikes but your not pedaling. Shorter cranks are necessary for a lot of riders.

[@EricBelisle-y1r]

Thank you for that, I dropped down to my original 32t, I felt a difference.

[@olik136]

when I switched from the normal 165 to 150 cranks I started riding everything one gear lower- but I didn't really notice that, because you can only notice the difference on the lowest and highest gear- both of which I almost never use on my 12s cassette.

[@garrywhelan9211]

@@justsayin3600 I'm a heavy rider on a FS bike with 180 cranks and I do just fine. Depends on the bike setup and the proportional sizes of the rider. I'm 6'7" tall and have a custom shock for my weight so travel is not compromised.

[@esshoul]

@@garrywhelan9211 can you share some info about that shock? More heavy ppl would love to find a key to not strike pedals onto ground so often

[@kayakutah]

6:24: Length for climbing (XC) 172.5 and for DH, 155. Quite a bit of variability, so be aware of your application. I'm over 70 and our Utah climbs are 3000 ft of climbing followed by 3000 ft of descending. I found that (at my age) going down in size resulted in Achilles tendon soreness until I got used to the greater torque required with the shorter crank arm length. I also have a slow cadence, so that could contribute. No real change in pedal strikes out here. Apparently, if crank arm height is "x", our rock heights are all "x+5"mm!

[@rinky_dinky]

70 and riding! you sir ,are an inspiration !

[@_Zane__]

I picked up a bike for my kid once, 24" tires, 175mm cranks 😂 I found some 145mm short ones to throw on

[@danielray1558]

It’d be awesome to try some of these- but at $500 a pop it’s an expensive test- I think it’d be pretty cool if you could pay $100 to rent two or three sizes for two weeks- run test them like this and send them back and then apply your rental to the purchase of your desired size. Just an idea @5dev

[@exothermal.sprocket]

I guarantee a lot of geometry on my 2015 Stumpjumper is messed up when measured against my particular body kinaesthetics. These puppies are at 175mm. Probably should be going 160mm honestly.

[@Ugoeh2]

I'm glad you made this video, and no snark is intended. I'd love for more people to know about shorter cranks. It takes about 30-40 hours to learn how to pedal a new size of crank. I had been taught how to pedal properly 25 years ago but could never do it on standard cranks. I'm 6'2". I just thought I was too uncoordinated. (Proper = pedaling in a circle, or as I was taught "pedal front to back"). I put on a set of 153s in 2020, was instantly faster, and remembered proper technique a couple weeks after putting them on. Here is what I want everyone to know: You do not size cranks by proportion of leg length. You size it by resulting powerband. When a crank is short enough, you can safely (for your knees) get max power down to about 30 rpm, where below 70 rpm on 165s it was dangerous for me. I am 3 or 4 gears faster on all sizes shorter than 153 down to 130 compared to 165. I can accelerate a hard gear from about 45rpm on 153's, and on 130's from about 55rpm. I can mash the gears all day and not cramp, no pain. I can also rev to the moon on 130's, and go well over 100 rpm on the 153s. I have about 1500 hours on 153, 140, 130, 137 and ended up on 145. The dirt bike analogy works somewhat: 153 = an open class 450 dirt bike. 140 is like a 250 dirt bike. Better in some ways than the 153. 137 and 130 felt similar, like a 125 2-stroke. Fast, but all top-end rpms. 145 was a nice blend for me. My 5'1" wife is on 120s, but she is unable to provide feedback due to arthritis and low body awareness. She seems to be doing ok. I may put the 130's back on for her.

[@brianwarshow129]

Any comments from the hardtail Single Speeders out there? Beyond the gearing changes that I suspect would be necessary at the expense of the top end, is much shorter too short? As a hobbit with no motor other than the good old fashioned "meat engine", this is interesting. Cheers.

[@suziekimura]

I'm 4’11” , riding in the sea to sky corridor. I've always wondered if shorter cranks would help with my stability going down. Would love to test shorter cranks out!

[@mtb3883]

Definitely try to switch your crank length. Not sure what lengths you have right now, but me (5'4") switching from 170mm down to 160mm really made a world of difference in pedaling uphill. I'm so glad they are making more lengths for cranks, hate the one-size-fits-all MTB mentality. Not everyone is built the same way!

[@5DEV]

Right crank length for the right sized bike. It’s simple! 🔥🔥🔥

[@davegee124]

its more for leg size not bike size,so you dont overstress your knees at the top of the stroke.

[@ctquadracing]

Is there a formula for the crotch-o-meter so we can measure at home?

[@antc5010]

That is over-simple thinking. Everything about selecting a bike always comes back to body size / bio-mechanics. Cranks, saddle height, bar width, stem, top and seat tube length... the list goes on. Not that simple!

[@LuciTulcea]

I'm a 5' 7" guy and had 165, 170 and 175 mm cranks. 165 was the best for me as I felt the rotation of my legs was more natural and comfortable. The other two cranks made me feel like stomping compared to the 165.

[@madzonic16]

Try 145mm, that's the maximum crank arm length for your height.

[@1969Escobar]

Great video, new thing on my wishlist, cheers

[@edmundhodgson2572]

Who thought 175mm cranks for mtb was the way to go? Oh yea, shimano. In the late 70's it was 180mm for bmx and 170mm for road so I get it. My old mate Mike Burrows (now past) always laughed about how long cranks are! Legend

[@j03y__]

Is there a good online calc that uses inseam and not overall height?

[@frankstrobel4350]

Just like bikes dont come with pedals (or usualy dont)…bikes shoukd come with no specified crank. The rider chooses the crank length online or at the shop during purchase.

[@mrshadow8244]

how many watts are you loosing because of short crank and smaller leverage? for DH or trail is maybe ok, but for XC im not sure.. I think it will be lot of watts ..

[@outsidefootdab4878]

I watch a video that explained watts and different cranks lengths in some studies and the changes crank length had negligible power loss Which found quite interesting.

[@davidkane8660]

Entreagued about this topic now

[@robinburt5735]

Not for me, my legs are abnormally long!

[@cayennepeppa707]

So glad you're talking about this. We go to fitters and they measure everything about us, but don't usually measure out the crank length. Ultimately, it's all about power generation, isn't it? Too long and it might steal away power, too short, it might steal away power. It would, totally, make sense that everyone's got a sweet spot where the angles and lengths measure up for the best power for each person. Thanks, all.

[@geoffreybarlow7958]

I want some short cranks to see if it helps with some knee pain I’ve been having lately

[@aasimmons]

It's kind of a jab in the side to make a video like this and then when the average Joe checks the 5DEV website, they can't get cranks from 5DEV that short.

[@ebl11111]

On the contrary i think. A video like this will wake everybody up and hopefully address this problem. 5DEV is way overpriced, especialy for the average Joe, and there are many alternatives out there. Ppl are hoping that the big *S* will wake up soon though since that would drastically take down the prices

[@maryelges]

I’m a five foot woman. I have been told to ride with way shorter cranks. I ride a canyon strive and would love to be on smaller cranks. Where can I get custom cranks for my bike. Txs

[@walterwest2583]

Trailcraft Direct Mount Cranks

[@laeljon]

Been riding 135mm for 10 yrs....

[@gclaytony]

The immediate impact of shorter cranks that I see is that seat height would have to be increased to get the seat/leg/bottom position relationship where it needs to be.

[@LemonySnicket-EUC]

And that changes your reach. The whole cockpit needs to be adjusted ..

[@leenevin8451]

In my mind the seat would be lower??

[@MarkJolley]

If tests like this were done "blind", 99% of people would not know the difference. There is too much bias to test when you know what you are on for most bike parts.

[@craigbest8644]

My Trek Remedy has 175s on a size medium, been looking at sizing down to 170 but having wayched this im thinking about 165s.

[@jimig399]

Yep...old news for me. I'm 6'2" and rode 175&185 cranks for most my life. 10 years ago I started riding more then ever and bought a new bike with a low slung bottom bracket and was forced to do something about it due to pedal strikes. So I went to 165. I couldn't believe the difference in cadence, control, ground clearance and comfortability. I do enjoy a nice 180 crank but it has to be on a bike with a tall stance and ground clearance. I think bikes are just too small these days for that size cranks. This is all driven by the geometry of new bikes and the low bottom brackets. We need bigger bikes so 175-185 cranks can still be utilized for their obvious benefit... leverage!

[@danielnolan2920]

Bobo, Seth?!? This is like the Avengers of MTB.

[@johnssmith4005]

Hmmm from now on those crazy expensive bikes 10K + would only make sense if they are CUSTOM made to fit the rider/owner

[@stevengoodwin3154]

I've wanted shorter cranks on my bikes for decades. Bike shops and others have somewhat discouraged me from going shorter. Recently, I wanted power numbers on my mountain bike, so I upgraded to a new crank. I went 5mm shorter and thought 10mm might have been better. I played around with some numbers on paper and confirmed after the first ride, going shorter has more positives than negative. ✌

[@maxxostmann]

I would love to try some shorter cranks as they would help get my feet out of the way for flip combos and the shorter cranks would bring my center of gravity closer and would help my spin tricks come around quicker!

[@charlesholland6851]

Should have bobo on in his female form. Lol😅

[@jeffreythree]

I dropped from 170 to 160. I prefer it and would like to try a 155. The only issue I had is the need to raise my seat. Seated pedaling puts the bars lower with 160 vs 170, but they are the same height when I am standing on the pedals.

[@MrLien32]

In the car world shorter stroke crankshafts usually means higher rpm and you can always gear for torque.

[@keatonbell7626]

Been thinking about 165s, but don’t know what the crank-o-meter would recommend for me

[@ceriway380]

I have aways thorght Road riding has to much influence in mtb for years ,my question is how dose a shorter crack affect seat high .

[@ebl11111]

If you switch from 175 to 155 mm cranks, raise your saddle height by 20 mm

[@troyesch6203]

It’s time for one of the big crank manufacturers to do a bigger study on this. If you take 100 people with a 32” inseam and have them all try 155,160,165 and 170’s and 90% prefer 160’s, then maybe bike company’s will start selling medium sized bikes with 160mm cranks. Do this for for all sizes. I’d be very interested to know if this is just a preference thing or if everyone my height would prefer shorter cranks.

[@gregmacdonald2237]

Great video and analysis of a very interesting topic! One thing I didn’t follow is why would e-bike riders prefer a shorter crank? Is it because crank arm position is less critical? For example having the cranks at the start of the ‘power stroke’ to get up over a lip or rock when climbing?

[@DougieFresh13]

Because they are lazy and it's easier....😂

[@cheesywheels]

This is because of the electric assist they get only when pedalling, so basically they want to keep pedalling to stay the same speed. So if they are pedalling all the time they want to reduce pedal strikes especially through 'gnar' and around corners. I hope that sort of makes sense?

[@cheesywheels]

@@DougieFresh13 Haha yes! I bumped into a E-biker on my unicycle and he said you are taking the hard option!

[@iross7345]

E-bikes tend to have a lower BB than manual bikes, to help keep the additional weight of the battery and motor low, which makes pedal strikes more likely. In addition, losing a bit of leverage is less of an issue with the motor taking some of the strain.