RAD is the new Reach: How to Size Your Mountain Bike

[@IDoBlues]

I think the best starting point is multiplying your height (cm) by 2.55 to get your reach. For me, 171cm x 2.55 = 436 mm reach. Use the RAD to then further pinpoint your bike's size. For more thoughts on bike fit, see kzbin.info/www/bejne/iZ-7lmWIot1-qKc

[@IDoBlues]

@@nevermind3486 I'm not sure to be honest. That's outside my wheelhouse. I'm all about Enduro/DH with heavy emphasis on descending.

[@RCKING1]

Rad is basically terrible. My last bike was technically bigger then my “ideal” rad and was still tiny. Shorter bikes are great for pump tracks and hopping around but be realistic do you want a “playful” bike when your riding down something out of your comfort zone or do you wanna feel safe and in the bike? Sense moving to my large geometron It’s been nothing but benefits on everything from the skull to boogie nights. A year later of owning it and I’m considering selling it and up sizing to an xl or possibly an xxl. But hey sizing is preference.

[@IDoBlues]

Ya, I'm hoping to go a little RAD+ with that in mind. At my level, I'm not flying down Boogie Nights or bouncing my way down Ladies, but I do like to pick my way down 7th or try to reasonably handle Corkscrew or Pingu. Maybe we need some sort of multiplier for Shore sizing?!?

[@RCKING1]

​@@IDoBlues Our tech trails are pretty tight! If rad made sense for fast mountain bike trails you would wanna size down not up. but even rad+ leaves me feeling like I'm riding a kids bike even on bookwus.

[@Hexsense]

On XC bike, I found that slight RAD+ can work well for seated position as well. But it require you to set RAAD really low to get to the RAD number. Meaning, very low bar. Like, using 0 rise bar and FSA Drop stem or Syntace Flatforce on thin headset cap with no spacer. If you set up the bike with tall bar and shorten the reach until you get to the RAD. Seated riding position feels way too cramped. So, instead of shorten reach to reduce RAD, lower stack reduce RAD as well. But it straighten the arm which is more comfortable. Still, setting up position at RAD makes my saddle slam rearward than I'd like. So, I set up slight RAD+ which allow my saddle to be a bit more center on the rail while seated comfort is still good.

[@mossy.trails5289]

I am in a very similar situation and have almost an identical RAD to you (774mm) but I am just under 5'6" interestingly. I currently ride a small Marin Alpine Trail 7 but it does feel a little small for me.....though the bike rad is about 800 or thereabouts so 'technically' big for my RAD. I'm looking at getting an emtb in the summer and can say with certainty that RAD or no RAD...I will not be getting a bike any smaller, I definately feel that for trail speed cornering and front-end stability, i'd rather be a little more stretched out as at the moment I tend to get a bit nosey and forward in corners. Reach on my current bike is 430. I'll be looking for something in the 440-450 range.

[@IDoBlues]

Yep, it sounds like a lot of people find matching their RAD puts them on a bike too small (especially when things get gnarly). I'm going to aim for RAD+ (I'm 5'7-ish and likely will have a reach around 435mm or so), but even then, some people seem to find even a bit RAD+ too short. Coming off a decade of back problems (and 2 back surgeries) I think a bike too long will be problematic for me, but for the uninjured riding steep/fast/janky stuff, going a little bigger than just RAD+ might be a better option (based on what people are saying from their experience).

[@ej1_drew]

i think the rad measurement can only go so far bc you can have a long reach and low stack height (and vice versa) and still end up with an uncomfortable bike that can have your weight displaced wrong. however if this is paired with joy of bike's approximate reach calculator (height mm x 2.50) then you might stumble upon some good fitment. i personally use the pythagorean theorem between stack and reach to know if a bike will fit and knowing bar height and stem length can be manipulated i can understand how the bike is going to feel based on the right triangle stack & reach form and what attributes it offers.

[@IDoBlues]

Ya, I like that reach multiple too. I usually use "height (cm) x 2.55" though and aim for slightly RAD+. I'm 171cm tall, so will be aiming for a reach of 435mm (171 x 2.55). As it happens, the reach of the small Forbidden Dreadnought set up as a mullet is 435mm--seems perfect on paper. I've already locked into my bars which have 12 degrees backsweep and 30mm rise so I'll play around spacers and stem to get the bike's RAD to sit between 785-795mm (my RAD is 775mm).

[@koklich]

I am exactly the opposite. Based on approximate reach alone I would usually fit L size bikes ( reach 476- 480), but my rad number is 89 cm and with that even most XL bikes are too small

[@OleTobs]

@@koklich Yes! Identical numbers, and I feel the same.

[@Cata7]

I'm about 170cm, wanted to get the mondraker Raze but it's 450mm in reach for the S size -_-. Can't find a decent bike with a decent reach for my height... 😥

[@IDoBlues]

At your height (same as me), I'd aim for 430-440 or so. Lots of options out there that size. I ride a small Forbidden Dreadnought with 435 reach. My Commencal DH bike is a small with a reach of 430-435.

[@user-ot9ti3ns2v]

My RAD is 810, my bike is 840, it's a medium frame. I have adjusted everything to increase the size [I, m 5’”9), I always feel cramped. I ordered a size large Giant trance 29 3.

[@jackkrimmel9031]

I am 5’9 and have always ridden a medium with pretty modern reach measurements, last bike was a 450 felt rly cramped and found myself heavy in front on occasion and just ordered a large frame with a 480 reach

[@teecee4459]

​@@jackkrimmel9031your arms must be like 5 ft long

[@harrygilbert3738]

This is where RAD limitations come into play. If you have exceptionally long limbs, then it all goes to shit.

[@teecee4459]

@@jackkrimmel9031 if you're feeling cramped on a medium frame, try getting an offset seatpost and moving your saddle back a bit.

[@martinkrutz5698]

@@harrygilbert3738 , yep I am 5'9 with a 6'6 arm span, and always ridden medium bikes and felt cramped, have just got a large Reign and it feels much better, If was to use a RAD measurement with my weird body shape, it would have me on a small!! P.S I also have long legs, and short body, and when standing straight my finger tips almost reach my knees. When racing road bikes, my custom build frame was 57cm seat tube, with 58 top tube and 140 stem. And as strange as those measurements were it placed me perfectly on the bike.

[@PsyCr0riginal]

Trying to make sense of commenters saying that a 'RAD' bike is too small, and i have a thought. I'm 188cm with longish limbs, reach on my bike is 485mm (almost perfect, 188x2.55), 40mm stem, 800mm bar with more than average sweep. My 'rad' is spot on, so it makes sense that the bike works so well for me, and i LIKE a stable bike. So im figuring all these comments saying a 'RAD' bike is too small or unstable is because of other factors, like chainstay length, suspension setup, saddle position. My stays are 445, seat slammed forward, and my sus is relatively soft/sagged but with high compression.. the bike is super stable and i have plenty of cockpit space.. and i pedal all day on it. Heck maybe ppl are using bars that are'nt wide enough so not getting that space that theyre looking for. In any case, 'RAD' for me is spot on and the bike is great, and ive been ridin for 20+ (aggressive AM Enduro and DH) years if that puts any strength behind what ive written.

[@BowzKnows]

Thanks for this! I am In Between small and med at 170cm on RM altitude powerplay that I am looking at. Currently riding a Med commencal clash which is probably a bad bike to compare to but it's all I have to compare too. Going to calculate my rad and see what's up. I ride a lot of old school dh and tech where I live which the clash is amazing at... Ugh it's stressing me out 😅

[@mike_millard]

I am about 5'10" and have a rad of 825mm. My current bike which I am selling as a reach of 480 and a rad of about 845 mm. With the 64.5 ha, a 77° sta. and the long reach the bike excels at going fast in a straight line over rough terrain. The problem I have with it is when it comes to cornering. Before my current bike I had a bike with a 430 reach and a 75° sta, it cornered great but the riding fast through technical terrain was challenging. The new bike I am getting has a reach of 458 and a 76° sta. so I think this will be a great compromise. Also I specifically looked for a bike that did not have too steep of a seat angle, I find 75°-76° is the sweet spot between climbing in and out of the saddle. With my 77° the nose of the saddle hits the back of my legs while climbing sometimes. I hope you are recovering well and riding as soon as spring hits.

[@IDoBlues]

Thanks Mike.

[@miguelfragoso7023]

How’s the new bike?

[@mike_millard]

@@miguelfragoso7023 looks great sitting in my basement, waiting for the snow to melt. Fat biking and skiing right now.

[@miguelfragoso7023]

@@mike_millard what size is it?

[@mike_millard]

@@miguelfragoso7023 size medium Ripmo AF

[@Emtbtoday]

It's all in Lee Mccormacks book Dialed it was him who discovered the RAD his own method that's now getting out to bike shop's for correct sizes and ignore manufacturers size guides

[@teecee4459]

If the M frame RAD = 762mm and L = 777mm, does it really even matter??? Seems like this stuff is way over thought.

[@IDoBlues]

IMO, choosing an M vs an L in the same frame makes a big difference in ride feel and is worth the thought.

[@teecee4459]

@@IDoBlues except everyone has a different opinion on whether you should be RAD, RAD-, RAD+, RAD++. Also, seems like no consistency in formulas or calculations. I see a bunch of people in comments tossing out RAD #s that don't even look close to right based on the formulas presented and bike specs. People with same height and inseam tossing out wide range of different RAD and reach numbers, it seems more confusing and inaccurate and misleading than anything. If I try to make sense of it all I'm afraid I'll end up with a really screwy bike not sized properly at all.

[@IDoBlues]

@@teecee4459 I think the easiest is aiming for a reach of height (cm) x 2.55. That's a pretty good start for most gravity-oriented bikers who don't already know their preferred reach.

[@ArmaniFlyHigh]

to me a enduro bike should have a good stack hight, reach and most of the endurobike have a 64 HA. My setup. XL framset from Raaw MadonnaV2 and a pike ultimate upgrade whit a 160 debonair Yari spring + C1 and offset 42mm as it stands 170mm and on the back i got the push 116 coil from push industry 205x65....okay, before this setup i had a Kona Process 153 Medium and it was not the right style of bike for me sinds the stack hight was to low and at some parts of the trail when the bike is collapsing, feels more like a Small bike...the more travel the bike has the more in it will collaps. then again...depending on your ride style.

[@Adventure-MTB]

Hello my RAD is 851mm and my bikes RAD IS 787.5MM smaller CAN be good do you think 63mm short is too much ?

[@IDoBlues]

Personally, I think 63mm RAD- is too short (especially on any sort of blue/black downhill trails). A lot of people think even slightly RAD+ is too short. But, it depends on your body and what terrain you ride. I'm going to aim for slightly RAD+.

[@BonafideToolJunkie]

Self-doubt is the new mindset ¯\_(ツ)_/¯

[@IDoBlues]

Three bikes later, I definitely use reach as my prime sizing number. For me at 171cm (5'7-ish), it's 435-445 mm.

[@BowzKnows]

I am glad I found your video. I feel like my current daily, a med 21 commencal clash had made me biased to long reach bikes. I am looking at altitude powerplay and my Lbs only has small. I am 170cm and the small range ends at 170 cm so I have been thinking all week if the small is what I want but the reach is 40mm shorter... I'm going to try and see what this math says I need. Great video and explanation thanks!!

[@IDoBlues]

You are about the same height as me (I'm 171cm). My sweet spot for reach is 435mm. Here is some more info - kzbin.info/www/bejne/iZ-7lmWIot1-qKc

[@BowzKnows]

@@IDoBlues amazing thank you so much!

[@Mkpn74]

Can’t you just get a lower bar, with a 9-10 deg back sweep/shorter stem/ lower your stack height? This will shorten the bikes rad.

[@IDoBlues]

For sure. I'm already running a 35mm stem. I could try a 12 degree backsweep bar but that might make the effective stem length a little too short and might make the bike handle weird.. With my bad back, I do like a bar with rise though. It's harder to shorten a bike that is too long than to lengthen a bike that needs a little more room. Overall, the 450 reach on my Orbea isn't too bad, but I think on my enduro build a 436 reach will fit me better than a 457 (the small and medium options).

[@gordanzzzz]

I think the biggest mistake U can make is buying a bike online . U need to try and feel the bike ,so my recommendation is rent a bike try it out .

[@IDoBlues]

Totally agree. It can be hard to find the model and size of the bike you are interested to demo sometimes though in some areas.

[@gordanzzzz]

@@IDoBlues Trust me in Italy it is a nightmare. I took me 2 months to find a bike I wanted and I found it in Germany

[@ragged9242]

It’s all just a good starting point. RAD is geared towards more decent riding. Puts you in the best position for that. XC and marathon are more seated riding. This is how you should adjust. For more enduro riding you want a more comfortable position for riding downhill as you are in that position for a good 5-10min and then adjust everything else around that. You can get your seating position to where it’s at a good point to climb to the next trail. XC/Marathon will do the opposite. Most of the time is in the saddle so that’s the position they want to be the most comfortable with and tailor everything else around that. Downhill racers are completely different as they are only going downhill and can tailor their bikes to that. It’s all just a good starting point and you go from there. Trust me. According the “height charts” I’m slated for a 485 reach, In seated pedal position super comfortable, stand up for enduro trail, with 30 seconds my back hurts like crazy. You need to use all these measurements to find your size. 2 people of the same height could have completely different limb and torso lengths. Shorter legs, longer torso, or vise versa. Same for arms. If you’re 180cm and chart says you’re a large, but your RAD puts you on a small then clearly your dimensions are affecting the outcome. I’m 180cm, RAD of 795mm. Height x 2.55 = 460mm reach.All those numbers are pushing me to a medium but here I am being suckered into a large of a 485 reach. My back kills me going downhill. Let’s also not forget, same bar and stack and increase or decrease reach numbers by 10mm either way. Higher/lower stack, rolling bars back or forward. It depends on your riding.

[@IDoBlues]

I only ride Enduro & DH and really like the 2.55 multiple as a starting point. Doesn't surprise me that if the 2.55 multiple puts you on a reach of 460 that 485 causes fatigue. I noticed the difference (in a good way) when I went down from 450 to 435.

[@AbideinChristFully]

I sold my enduro because it was sooo much harder to climb compared to my older school hardtail. Now I'm considering an ebike enduro build.

[@IDoBlues]

Orbea Rise!!!!!

[@22Jeffers]

Cool story bro

[@MrChadLedford]

Going with Rad sizing hurts my back terribly.

[@Plasmo20]

Great RAD discussion. One thing to add. Wear your MTB shoes when measuring the RAD. I noticed you in low stack thongs, so I recon you missed 10mm of RAD there. Im 175cm with 870 inseam, so all legs. I bought a used Large Rise (because the online charts said L = 170 - 185). I couldnt get the bike to turn in tight switchbacks and was constantly running wide mid corner, no confidence in the front end grip. My RAD = 810mm. When measured against the Large I was 35-40mm short in the RAD measurement. I then bought a used RISE in Medium as that is 24mm shorter (450mm) in the reach than the large (475mm). My RAD is still on the short side even on the medium. So to fix this I have to get more sweep in the bars. The medium feels like I am better able to push the front into the ground in corners to load up the tyre. I am wondering what a SMALL would be like. I recon I have been on bikes too big for me for most of my 14yrs on MTBs.

[@IDoBlues]

Yep, good point. ... always with bike shoes on.

[@rolffuchs2737]

I guess it is about riding preferences. Like me, I prefer more longer rides, I have long legs and a shorter bike feels really uncomfortable for me and with 84 cm inner length and Length of 5.8 it is always difficult with this really short seat posts, because there is not much left and I have to go for a 420mm.

[@mattroland5943]

Another Bike Fad!

[@IDoBlues]

I think maybe a little, but there is something to it.

[@CasperRc81]

Raising bars how ever you do it shortens the reach quite a bit while increasing the stack and allowing your elbows to be bent and a straighten back. So maybe stick with a bike a little longer so you can both directions.

[@IDoBlues]

...and the slacker the bike, the more pronounced that is.

[@elkat_bori_pr7791]

5'7 too. My RAD is 820mm

[@IDoBlues]

Is your RAD 820mm or is your bike's RAD 820mm? If you're 5'7 and have a RAD of 820mm, you must have pretty short arms. I'm a touch over 5'7 and my RAD is 775mm and I don't have long arms. ....but I'm guessing your bike's RAD is 820mm. My current bike (medium Orbea Rise) has a RAD of 830mm. I think it's a touch too big for me. I'm going to be aim for my next bike to be slightly smaller, but still RAD+ (20mm over my RAD, so hopefully sitting at 795mm or so).

[@tombeck129]

You don’t have to guess the RAD from bike geometry numbers. Get a triangle calculator and enter REACH and STACK and you will get the RAD. But have you noticed that these RAD discussion always talk about power movements from bunny hops to huge jumps and bikes with crazy low head tube angles? How about XC riders? How about the 90% of riders who will never do a bunny hop let alone huge jumps and crazy DH runs? They will all feel cramped (especially with the steep seat tube angles) on a floppy bike that tracks like shit when climbing.

[@tjb8841]

That’s incorrect. RAD refers to the Roder distance, not frame dimensions. The key is that you don’t hold on to the head tube, so spacers, stem and bar all add or subtract from that starting point you discribe

[@tombeck129]

You are absolutely right, you have to add to the calculated number the additional 1-2 inches. But my real point is about RAD being a completely arbitrary number, largely pushed by those who want a shorter reach. Now some guy came up with the negative inverted stem to drive home the point that it is all just arbitrary stuff.

[@mtbmike9866]

RAD will always guide you to a smaller bike. Great for handling and tossing around but not ideal for DH stability and Gnar. If I were in your shoes, go toss in a 170mm 38/Zeb on your Rise and get a 216x63 shock out back with 1 offset bushing and go Mullet like my bike but even more aggressive. This will get you a 63.5-64 HT angle but more importantly it will reduce your reach to 430-435mm

[@IDoBlues]

MTB Mike! Thanks for commenting. I've been keeping a close eye on your Rise mod. It's great! Ya, we definitely have gnar here! Love the Shore! From what I've felt so far, 435 mm is a pretty sweet spot for reach for me. If I was keeping the Rise as my only bike, I'd be hitting you up for more tips to convert mine for sure! My current plan is to keep my Rise as a trail bike--the weight & geo are great for that as is, and I'm only 130-135 pounds so the Fox 34 is plenty for me on blues & even lower blacks here. But, for the ever present gnar here, I'm going to build up a full on enduro. I'm going with a Forbidden Dreadnought with an EXT ERA fork (170mm) and an EXT Storia coil (158mm on a high pivot). I'm also going to set it up as a mullet--Forbidden has a specific linkage available for that to keep the geo on point. Funny enough, the reach on the small Dreadnought is 436 mm--right at what I think is my sweet spot. The medium is 457 mm. The reach on my medium stock Rise is 450 mm. The Dreadnought in general is a pretty big bike (long, low & slack). The wheel base of the small is pretty much the same as the medium Rise. I'm actually typing this from a hospital bed. I just got out of a back fusion surgery this morning. So I'll be off the bike until 2022 to rehab and will be working on that Forbidden build while I do. I love what you are doing on your Rise. Your last jumping vid was great. Keep 'em coming! (and thanks again for the comment)

[@mtbmike9866]

@@IDoBlues I’ve had a parking lot test on a mullet Dreadnought. It is for sure going to be an amazing bike. The only thing is the rearward axle path under compressions and hard berms causes the wheelbase to not shrink as much on other bikes so it feels a bit different (according to the owner) but he got used to it after a few rides. Man, glad the surgery went well and I hope you get better soon!!

[@IDoBlues]

OK. I have to ask. What size of Dreadnought did you sit on? And how tall are you? Did the size feel right? How about the owner? How tall are they? I heard one guy 5'7 say the medium felt pretty big. As of now, I'm going for the small with a reach of 436 mm, but I'm keen to hear from others who have tried one.

[@mtbmike9866]

@@IDoBlues I am 5’ 7.5” without shoes but have long arms and legs. My wingspan is 6’1” and inseam is 32”. His Medium felt great. Similar to my S3 Enduro, but a tad smaller. He is 5’6” and fits him well also

[@IDoBlues]

@@mtbmike9866 I ended up with a small Dreadnought (435 mm reach). LOVE IT! kzbin.info/www/bejne/aYSppIJ6qrGraLc I'm in the process of ordering parts to enduro-ise my Rise. I'm going for a 160/160 mullet. Fox 36 up front, EXT Arma coil for the shock. Offset bushings are in the mail.

[@Gufolicious]

I went through your situation 2 months ago. Trust me rad is nice if you do pumptracks and bmx style moves but for going downhill it sucks ass. I would not do it. I did it and i reversed it again. Ps: you have a long torso and long hands so its even more crucial.

[@IDoBlues]

If we go back to just reach, my old medium Evil Following was 419mm and it felt great. My medium Rise is 450mm. It does feel a little more stable with that longer geo but also is a bit slacker and has slightly more travel. The enduro bike on the top of my list right now is the Forbidden Dreadnought. In a small, it has a reach of 435mm (more than my medium Evil). In a medium, the Dreadnought is 457mm. I talked with a guy my height who tried the medium Dreadnought and he thought it felt too long for him. A guy I'm working with at my local bike shop took my height and inseam and suggested considering the small. Hence me nerding out on this size stuff. I'd love to demo both sizes, but that might be tough with the Covid supply chain sh-t. With that small Dreadnought with the slack head angle, I could always go with a 50mm stem (vs my usual 35mm) if I want a little more. Also interesting is the wheelbase of the small Dreadnought is more than my old medium Following and is pretty much the same as my medium Rise. I'm such a light guy...I'd be a bit worried about over-biking with a medium Dreadnought. But ya, the intention is for some steeper more technical terrain on this, so I hear you on being careful about ending up with a glorified dirt jumper.

[@Gufolicious]

@@IDoBlues yeah, exactly dont get me wrong the RAD sizing makes sense in some situations like all of the ones lee and alex are in most of time. But for average riders who cant and dont need to bunnyhop park benches or flick through the air a slightly longer bike has countless benefits. Take mondraker for example they have the forward geometry and their bikes ride like tanks. Allthough i came from mondraker and i love my rise. Orbea is king for me now especially price/value.

[@TheStryder400]

@@IDoBlues I'm in a similar situation - looking to upgrade my 2018 Banshee Rune, and a small Canyon Spectral (150mm, 27.5") has bigger reach 435mm (Rune 427mm), slacker HA by 1deg, slightly longer wheelbase, and steeper S/tube angle, but the Canyon has a higher stack height. And some people say that this makes the bike seem slightly bigger than a bike with a lower stack height (bikes with similar reach numbers) I am very comfortable with the geo of the Rune - a dilemma as I don't buy bikes every second month.

[@ivoyanakiev6844]

Looks like you have race face turbine stem on tour bike.If you are still using it,these stems ase designed to have 0 gap on the top part.Meaning the top two bolts should be screwed all the way! ;)

[@IDoBlues]

Whoa...good eyes. Ya, it is a RF Turbine. I was experimenting with putting in some rubber strips to see if noticed any vibration damping. I had the bolts torqued to the recommended amount, but it did leave that gap. Result: no noticeable difference...rubber and gap has been removed.

[@jorgmischke5839]

I'm 5'11' and have a RAD (about 84cm) which is pretty much close to being bang on with my bike's setting (454mm reach). Owning my bike and having ridden other bikes with significantly more reach (around 480 - 495mm plus more stack, RAD unknown but bigger) I can only say: My own bike is too small for my preference (did have less experience back then). On larger bikes, I ride with more confidence, even with very good handling (I'm not an ultrafast Pro rider) and an overall better experience. So, for me, the RAD concept is not what I'd go for with my next bike/ bike build). Probably I'll find myself at 480mm reach and somewhat good modern Enduro stack. And also: What's the rationale behind RAD measurement? You are experiencing way more dynamics, upper body load and stability/weight shifting requirements on a bike. A static measurement of a tall standing rider with shoulders low appears somewhat arbitrary.

[@IDoBlues]

Yep....a lot of feedback saying similar things. I think for where I ride, RAD++ is the way to go (which then might mean something other than RAD altogether).

[@josephfarrugia2350]

RAD measurement/sizing is for maximum & full range of movement; which is achieved when you hinge very low. Anything over RAD & you're getting less range of movement, not more. ie: you got that right (or partially right), objectively You are experiencing way more dynamics, upper body load and stability/weight shifting requirements on a bike when your sizing is RAD. If full range of movement isn't your priority & you're confident you won't hurt your body in the long run, other sizing methods might appeal more to you.

[@karlxu782]

@@IDoBlues I highly believe people should start to put the body weight into this measurement. I am 6 feet tall, 67 kg. Everybody tells me to get a large frame with 470+ reach, but I really feel I should get a medium frame with less than 460 reach. I guess that not everybody has experienced being 180cm tall but only 150 lbs, including the bike engineering. Less body weight means less momentum so you don't need such large base to be stabilized, also it is hard to through the small weight over the axles to initiate the manual or stoppie .

[@morganrandell.]

@@karlxu782 good point. I am a 5;10 and 165 lbs and I like a smaller bike with more agile turning.

[@oOOlivierful]

Rad measurement will only get you so far, it can even steer you on the wrong path. For example someone that measure 182cm with long arms could get the same RAD measurement to someone 172cm with shorter arms. Because having longer arms can drastically reduce the distance between your hands and feet, reducing RAD measurement. Do you think these two individuals should ride the same size frame? Probably not... I'm 183cm my RAD is 795mm and ride a bike with a RAD of 880mm(470mm reach, 66 HA) and would absolutely not want it smaller. My riding consist of 50% climbs 50% descends, mostly single track tech trails, flow trails, pump tracks etc. What seems to be more accurate is height of rider in mm multiply by 2.55 to find your reach and go from there.

[@IDoBlues]

The height x 2.55 is my starting point too. I think it really works for most people. Then if stuck between sizes, you can use RAD from there (see kzbin.info/www/bejne/iZ-7lmWIot1-qKc ). A 795 mm RAD for someone 182cm tall is pretty far along the bell curve (and using RAD does break down for people on the far edges of the curve,). Is that with your riding shoes on, feet pedal with apart, arms bar length apart and looking straight forward? I'm 171 cm and thought my RAD was 775 mm but measured more carefully and it turns out its 810 mm. My bike's RAD is 825mm. My reach is one off the 2.55 multiple at 435mm (see kzbin.info/www/bejne/iKGbmX2LaM6eb7s ).

[@oOOlivierful]

@@IDoBlues I agree, really good videos by the way. Thanks.

[@-NewDay-]

I sized down because the staff guy said I’d be a xs in Liv bikes. He didn’t have me test ride a bike so I hope it fits. It’s being put together at the bike store

[@IDoBlues]

How tall are you? Did you pick it up? Does it fit?

[@RobertFullStop]

I'm at the very top of size M, but have long wingspan and went for size L on my 460 mm reach 2023 Marley 275, which has a top tube of 629 mm - 620mm being top tube length on a M size Scout, which is what I would get for a 29in aggressive hatdtail. I feel I'd prefer longer reach for enduro and normal reach for trail riding. Considering both bikes have similar top tube lengths, I shouldn't feel too different. Any thoughts? Great video 👍🏼

[@IDoBlues]

How tall are you? Some more thoughts here.... kzbin.info/www/bejne/iZ-7lmWIot1-qKc

[@RobertFullStop]

I'm 177.5 cm... I think that's 5 10? Just measured my rad and it came at 780 mm and bike RAD was 850 mm, which doesn't feel bad at all to be honest and I'm not sure I'd have it any lower. I have to say that bike is specced for 130-140 mm travel fork and I'm running 150 mm and 50 mm rise bar on a stock stack of 630 mm + 16 mm spacers...so not L measurements as intended by the manufacturer. I was looking for something more flickable, but I'm tempted to try it mullet now! Thanks for the references 👍🏼

[@IDoBlues]

@@RobertFullStop At 177, I think a reach of 460 sounds pretty good for an enduro bike. If your armspan is quite a bit bigger than your height, the RAD stuff might not be super applicable for you. I absolutely love the mullet setup--I converted my ebike to one and bought a stock mullet for my enduro and dh bikes.

[@ciervo111]

I'm 5'10. 840 mm inseam and 840 mm RAD. Orbea Oiz L frame is just spot on with 446mm reach and around 840 RAD. Feels great!

[@IDoBlues]

Awesome!

[@teecee4459]

If you're 5'10", your RAD isn't even close to 840

[@enriquilloMTB]

Mmmm…. Algún dato está extraño, mides 1.55mts? Y tienes una bici talla L? Yo creo que mides más alto.

[@rmack611]

So my rad is 879 my reach with the calculation is 459 The rad using a triangle calculator on a med dread is 774 with 461 reach and large 794 with 484 reach (I do understand that’s without the rest of the cockpit) idk if those other numbers help or hurt because my reach def say medium but my rad says large!? Which number in your eyes is more important? My current bike is a pole Evolink (I do want a bit smaller) with a 480 reach and a rad of 809! I also understand maybe forbiddens might not fit! I have no opportunity to demo

[@IDoBlues]

I'd start with the reach formula: height (cm) x 2.55. If that clearly points you to the medium Dreadnought, I'd go with that. And then set up your cockpit (bar rise, backsweep, stem, spacers) to get as close to RAD+ (10-20mm) as you can. Check this out if you haven't already -> kzbin.info/www/bejne/iZ-7lmWIot1-qKc

[@rmack611]

Thanks for the reply! We all appreciate how helpful you are on here!!

[@IDoBlues]

@@rmack611 Thanks. I appreciate that.

[@Zetler]

If I listen to Joy of Bike my ideal bar width is 760mm. That's a no for me. Because of that, I don't trust their RAD.

[@IDoBlues]

What's your wingspan? How wide are your bars? How tall are you? What's the reach on your favorite bike?

[@darrinkulyk9560]

Im the same size as you and bought a Med ..... everything is Adjustable 😎

[@IDoBlues]

adjustable-ish

[@Everyday-man]

How can you do rad for buying a bike online tho?

[@IDoBlues]

You can't. I'd buy using reach (height cm x 2.55) and then fine tune the cockpit once you have it.

[@FranciscoAlvarez-nl3of]

​@@IDoBlues in inches?

[@IDoBlues]

@@FranciscoAlvarez-nl3of multiply your height in inches by 2.54 to get your height in cm. ....then use "height cm x 2.55" to get get your starting point for reach. (....or just multiply your height in inches by 6.477)

[@magnate2372]

Nice video! Were you running stock stem and handlebar when you measured the RAD? If not, what are you using? I’m trying to figure out what the RAD is of a stock medium Rise.

[@IDoBlues]

I'm using the stock stem (35mm) on the Rise but replaced the bar with a OneUp carbon (for the flex). The original bars were 740mm wide and had 8 degree backsweep. The OneUps were cut to 750mm and are also 8 degree backsweep. On the enduro bike build I'm working on, I went with a SQLab 311 fl-x bar at 740mm and 12 degree backsweep. I'll need to play around with stem length to get the right RAD/reach, but my guess is I'll need a 50-60mm stem on that one.

[@magnate2372]

@@IDoBlues thanks for the info. I’m in between large and medium and will go with the medium since it’s much closer to my RAD

[@IDoBlues]

@@magnate2372 If you are riding gnarly stuff, I'd suggest to aim for RAD+. You can play with your bars and stem to zero in on that.

[@jazzsqueal]

@@IDoBlues how are you liking that 311 bar? I'm looking at the same one

[@IDoBlues]

@@jazzsqueal It was too narrow at 740mm (once my grips were on). I switched to the 30x with 12 degrees of backsweep and cut it to 760mm (putting my hands at about 740 on the grips). I do love the 12 degree backsweep.

[@BJJandBS]

A person with incredibly short legs and a super long torso will be SCREWED by a Rad measurement and will be going over the handlebars.

[@IDoBlues]

I agree. People on the far ends of the bell curve when it comes to arm & torso lengths will have to pay more attention to reach-- height (cm) x 2.55.

[@BJJandBS]

@@IDoBlues can you explain that?

[@IDoBlues]

@@BJJandBS Most people have an arm span that matched their height. That works really well for using RAD (I actually like 10-20mm RAD+). But some people have really long or short arms compared to their bodies which skews things a bit (those people are on the edges of the bell curve compared to the majority of the population). For those people, using RAD might not be a great method. But using their height (in cm) x 2.55 might help as a starting point to look at reach. For example, I'm 171 cm. Multiply that by 2.55 and you get 436mm. That's a good starting point for reach for me. In fact, I ride 435mm reach and it feels great. That bike is 15 mm RAD+ on me with the cockpit setup.

[@BJJandBS]

@@IDoBlues so when I do my calculations like that mine comes out to 457.2cm. So a bike that would be close to fitting me would be one with a reach of 457cm reach? Because I find that the most comfortable ones for me thusfar are about 500cm reach. My torso is super long and my legs are super short

[@IDoBlues]

@@BJJandBS It sounds like you are about 5'10 or 5'11 (179cm). Ya, at that height, a bike with a reach of 457 is a good starting point. The difference between leg & torso length shouldn't make a difference. If you have extra short or long arms, that could make a difference. 500 reach sounds long to me for your height, but if it feels right, who am I to say. That extra reach would feel great bombing straight technical terrain. My guess is a bike closer to 460 reach would feel more maneuverable. And this is all about standing position. A bike with 460 reach might feel a bit squished on the saddle with the modern steep seat tube angles.

[@pcaddict1337]

In my opinion, the RAD measurement is total BS. I watched the Joy of Ride video and the way they talk about it seems to have more on common with starting a cult that with mountainbiking. They talk about how much leverage you have on the bike, which is a bit strange, because i like to ride my bike, not do a deadlift with it. Also they tell you to jump, close you eyes, pull your shoulders back and make a mark. I dare you to do that 3 times in a row, and I'll guarantee that you will have 3 diferent measurements with an error of a couple of centimeters. But they talk about this arbitrary number like it's the be all end all, and a bike RAD measurement bigger than your measured RAD by just 2 cm is too big. Ride your bike, make a mental note of how it feels on the trail, look at the bikes geo numbers, and bases on you riding experience and a bit of bike geometry knowledge you can make an educated guess on what a better fitting bike should be for you. You can't boil down all the variables of bike type, preffered trails, body anotomy, phisical condition, cockpit setup to just one number. Just think about it, this isn't rocket science people.

[@IDoBlues]

I think it offers a good guide to get people started on zeroing in on what works for them. I usually start looking at bikes based on reach.

[@pauldevlin6382]

I’ve measured my RAD several times over the past couple of days and I now have 3 or 4 different measurements 😅

[@IDoBlues]

@@pauldevlin6382 It's so true!

[@22Jeffers]

Issue, as I see it, is peoples varying ape index. You could be tall with short arms making you need a big RAD, but then you reach might be too big. Or the reverse. You might be short with long arms, making your RAD short but the reach way too cramped.

[@IDoBlues]

I agree. People on the far ends of the bell curve will have to pay more attention to reach.

[@22Jeffers]

I probably suffer with the latter. I’m 178cm (5ft 10”) but have an arm span of 183cm (6ft). So this RAD suggests I get a medium. Which is fine for standing up on technical and downhills. But for XC, it feels a bit cramped.

[@IDoBlues]

@@22Jeffers Oh ya....I think the RAD works better when the focus is on the descents for sure. Geared towards the standing position.