BIKE FIT: How to Size Your Mountain Bike!
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- čas přidán 13. 06. 2024
- Go by the numbers! Frame, Bars, Stem, Cranks, Dropper, Brakes! Reach & RAD! Fit your mountain bike to your body.
If you would like to purchase a set of Catalyst pedals (best flats out there in my opinion), consider using this affiliate link. All proceeds I make from this affiliate link will be donated to local trail builders. You can try the pedals, and if you don't love them, you can send them back for a full refund. bit.ly/catalystpedals
0:00 Intro
0:59 Frame: reach
1:27 Frame: RAD
2:25 Bars: width
3:28 Bars: backsweep
4:21 Bars: rise
4:46 Spacers
5:09 Stem
5:42 Cranks
7:37 Dropper
7:45 Brake Rotors
Music:
Brazil Samba from Bensound.com
#mtb #mountainbike #bikefit
For the love of mountain biking! - Sport
Thank you verry much man! This is the best i'v seen on a bike sizeing so far!
Thanks. I appreciate that.
Best informative video I've seen, and a previous engineer, I look for tech videos. Well done!
I really appreciate that. Thanks!
Brilliant punchy delivery. spot on
Thanks. I appreciate that.
Very good information! Exactly what I needed. Gr from 🇳🇱
Best video in the world on bike sizing ever!
Thanks Lynn!
Ok. after years of riding and trying to find solutions this video made more sense than anything I've watched before. Been wanting to upgrade my bike for a while but sit on the fence in fear of throwing money at what might work. it's not a cheap hobby. So cheers for the great video
Thanks. I appreciate that.
Good stuff, similar stuff on Joy of Bike Channel. I'm glad i stumbled on these videos when I did. I just bought a MTB a few days ago and realized, after watching these that the reach and RAD of my bike was too long. This was confirmed in my riding as I really had a hard time bunny hopping, doing wheelies etc. I could probably have shortened the distance with a new stem and bars but I'd rather have a bike that fits right. Luckily I'm within my 30 days to exchange and will be reducing to a small which fits my reach and RAD measurements.
Ya, and reducing reach using bars and stems can only go so far. You want to make sure you keep your effective stem (ie hands) at least 20mm ahead of the steer tube axis or else things could get twitchy at speed.
Another amazing video. Thanks so much you have given me piece of mind I have chosen the correct size. Buzzing.
Great to hear!
This is the info I needed to fit a new Salsa. Thx
I think the best starting point is multiplying your height (cm) by 2.55 to get your reach. Then use RAD to further pinpoint your bike's size. For those of you that fall outside of the bell curve when it comes to arm and leg length to body proportions (any Michael Phelps out there?), some of the numbers here might seem a bit off--especially RAD, but bar width and crank length.
If you would like to purchase a set of Catalyst pedals (best flats out there in my opinion), consider using this affiliate link. All proceeds I make from this affiliate link will be donated to local trail builders. You can try the pedals, and if you don't love them, you can send them back for a full refund. bit.ly/catalystpedals
Tnx! this is actually great! Just what I needed!
Thanks. I appreciate that.
This Video is Gold thanks!
Thanks. I appreciate that.
with this measurement, it means that the longer hands you have, the lower your RAD is. The smaller your rad is, the smaller the bike. But yet you have a big reach, cause your hands are long.
This is error prone.
I like to start with the reach formula as the main starting point (height cm x 2.55) and then use RAD to zero in on your cockpit setup (which takes the stack, bars & stem into consideration).
thanks a lot man. this helped a lot
Great to hear!
I'm 70 and 5'9" tall. I am more interested in climbing (welcome to the Wasatch range!) have a relatively slow cadence and use a 30t oval ring. I tried a 165 crank and ended up with a little bit of Achilles tendon soreness. For me, my 175's work better. My wife has pretty long legs and for her, 170 (Vs. 175) has eliminated knee pain. I think she could go shorter, but I don't think I'm able to. Also, just to remain outside the bell-shaped curve, I find that having my bars at the grips about 5 cm above my seat reduces stress on my lower back and takes some pressure off my palms. As a data point, I can climb anything on Slick Rock except for one 4 foot section at the top of a particularly heinous climb and there's never a point at which my front end gets too light to steer. So, I think these guidelines are great, but you still have to be willing to deviate from them on a case by case basis. My RAD, reach, stem and bars all fall well inside these parameters, though.
Yep, every body is different. Your point about finding the right front end height to keep pressure off the palms is a good one. For whatever style of MTB riding you do, you want a good centered body position where you don't need to put weight on the hands/bars. For me, with my back injuries, that means a slightly higher front end to reduce the amount of hip hinging. Ideally, I could hip hinge more, but I need to adjust for what my body can tolerate.
Interesting that you get more Achilles pain with shorter cranks. I wouldn't have guessed that would happen. But theory can only go so far.
All the stuff I talk about is geared towards gravity riding (emphasis on the downs). I'm pretty ignorant on anything do to with road, gravel or even XC trail riding.
Very interesting. Thanks for a great video explaining proper sizing as everyone is different. I was fitted to an XL when based on height I’d ride a L. Now I feel as if I’m riding a canoe on the trails. Debating on getting a L or keeping the XL and upgrading in a couple years.
And not all Ls or XLs are the same.
I guess we know who will never be a sponsor. Lol. Thx for the great info.
☕👍
Amazing discourse
very comprehensive video
Thanks!
I find the measurement between the centre of my seat, to stem, finds the best fit. Reach is good, but when seated 85% of the time, stem length and seat angle has a greater impact on comfort and control.
That's a good point. This fit guide is meant for gravity riders focused on the downs in the standing position. Downhill, enduro, freeride.
Get off your seat
@@IDoBluesthis is the other problem with all these formulas - no context usually given in any of the videos. I'm not standing or doing any "shredding", just riding it around, so this stuff probably has nothing to do with sizing for me.
@@teecee4459 Correct. These suggestions are for gravity riding mountain bikers and focus on the standing position when descending.
Doesn't sliding the seat around offer enough adjustment?
Interesting breakdown but I think the BB height of a bike factors into the crank length. I like a 170mm but I'd almost have soil strikes with my current bike running those.
this definitely has its limits, at least past the RAD part.
I'm 6'6 with a 6'10 wingspan and 38in inseam, this would put me on 850-900mm wide bars and 185-190mm long cranks. I do agree with the reach and stack numbers tho, I prefer a 50mm riser on a single size down from what the manufacturer recommends which lines up perfectly with the RAD numbers. Probably a great bar/crank sizing video for "normal" sized people, definitely good for frame size!
Absolutely. These "start here" numbers start to collapse when you move far to either end of the bell curve.
Thanks for the video. By the way I make my coffee don't need Starbucks or wars
I'm 5'9" (5'10" with shoes on) and have an arm span of 6'3" so multiplying my height in CM by 2.55 has never worked for me when it comes to determining ideal reach. By the numbers I should have a reach of 446mm - 454mm, but based on years of experience I prefer a reach range of 460mm - 480mm. Interestingly the RAD figures seem to be much closer to what I prefer. Thanks for the info.
Those knuckles drag on the ground?
@@alabaster4263 no, but my fingertips do.
of course, my arm span is also bigger than my height. I look completely normal. These measurements and estimates are error prone. Life doesn't work this way guys.
My height is 177cm, arm span 182cm, “RAD” at the wall in boots 80.5cm, and my new bike size L has RAD 85.5. So… I am very beginner and I think I should return it and replace with size M, since I just got it and didn’t try it yet… handlebar upgrade from 7 degree 750 to 12 degree 780 should decrease reach and RAD 2-3 cm isn’t it?
@@alabaster4263patrick ewing
Thank you for the detailed information about the bike fit. I'm a XC racer and I didn't found the crank length measurements for the XC format. You mentioned the downhill and enduro/trail formats but not the XC. Currently, I'm riding on 175mm cranks, 36T oval chainring and my height is 167 cm, i don't know what is the perfect lenght of the cranks. Moreover, I don't want my power transfer in pedal strokes to be affected.
I'm sure you know a hell of a lot more than me when it comes it leverage, power & torque than I do!
Seems like I am pretty bang on
Apparently according to RAD, my bar width Max should be 866mm and my Min is suppose to be 826mm... I'm riding 800s! With shoes I'm 6'2" and my measured RAD is about 34-35ish inches on the bike riding a S4 Stumpy EVO in the slack and low positions with about 25mm of spacers and a 35mm stem and a 170mm Fox 38 giving me about 10mm of additional stack height. Arm measurement from floor to handlebar width was 33-35 at 800mm-860mm width. My arm length is a bit long at 77.5in (6'5") or 196.85cm. And, apparently I should be riding 178mm for my Min crank length with my 35in inseam according to the Enduro calculation of 0.2x889mm (182mm cranks according to the Max calculation). I'm on 5DEV 165s. RAD doesn't seem to work for me. I like a Large bike with a reach of 465-485mm The Stumpy EVO S5 was a bit too long but felt incredibly stable at speed, but hard to keep traction on the front wheel and slower in tight corners. My Stumpy EVO S4 feels good at roughly 470mm and I have more options with increasing stem length. A good balance of stability and nimble. The S4 Enduro with a reach of 480mm feels perfect and still has a wheelbase that doesn't feel long in corners. I believe in RAD and it works but in the end it's more feel with my obnoxious body type.
OK, so you are about 188cm tall. The recommended reach starting point would be about 480mm which sounds like aligns with how things feel on the S4 Enduro. I'd then fine tune cockpit based on your RAD (I like 15mm RAD+, but that's just my preference). But if you have freakishly long or short arms in proportion to your body, using RAD might not work. And you need to be very careful and precise measuring your own RAD--it's easy to get that wrong based on shoulder position and not looking straight forward when measuring. If you have fairly normal arm-to-body proportions, you wingspan should be close to 188cm. That would put your recommended bar width between 790-830mm (so you 800mm makes sense to me).
Ya, with your 35" inseam, the recommended crank length would be between 168-182mm. Your a pretty tall guy, so those numbers make sense to me and if you like short cranks (I do too), 165mm doesn't seem too far off that. A lot of guys your size would likely go for 170 or even 175mm. I agree though, the top end suggestion of 180mm seems a bit crazy.
I'm thinking that RAD should be measured from BB to middle of handlebar grip since you are standing with your arms handlebar width apart
I didn’t liked to go biggest dropper, because the seat is below my knees while pedals level. Didn’t like that feeling and went back to old dropper
Ya, that would be tough on the body to drop it that low!
I went n+1 two years ago when purchasing my bike with a reach of 470mm 😮 Im 173cm, and according to the RAD calculation, my bike reach should be ~440mm. Now Im wondering why I have hard time cornering apex! 😮 Thanks for the info… never had a bikeshop being able to explain that to me with a proper method using math. Thanks! 👍🏻👍🏻
ya, but you probably plowed steep rock gardens like they were smooth asphalt!
Hey, just talking to a bike fitter of 40+ years about the RAD measurement and the REACH calculation based on a persons height. He suggested that neck/head length needs to be discounted from the reach equation (height x 2.5) as they are not a factor in reach function of the rider. Instead he recommends from the sternum to the floor is the better, more accurate, measurement points.
How does that sound? Sternum to floor X xx.x. Not sure what the xx.x number will be but see below for my thoughts.
My height is also 175cm so using your calc
height x 2.5 (175 x 2.5=437).
My RAD = 820mm
My Orbea RISE Medium Reach = 450mm so the bike is a bit long for me, but workable with swept bars etc.
The RAD measurement confirms this on my bike as its about 20mm short of the string across the bars.
My floor to Sternum = 143.5cm, so to get to 437mm (from the height x 2.5) then Sternum Val X 3 = 437. So does this number work better?
I ask as the bike fitter said that those with long or short necks and funky shaped heads will introduce an amount of error into the calculation that can be removed by measuring the parts in the reach function only.
Your thoughts?
Ya, that does make sense. RAD doesn't take the neck/head until consideration, but ya, that reach equation does. It makes sense but to though. I wonder how big the variances are across the population, but you could be on to something.
Hello and thanks for this interesting video, where does your formula come from ? The reach recommendation especially (height x 2,55)
Thanks !
Modified from Joy of Bike and Lee Likes Bikes. I think they suggest x 2.5. I think starting at 2.55 for enduro and DH is a better starting point (with adjustments for your preferences).
I love the pencil method. Very clever and appropriate. I just wonder why your not supposed to lift your heels to at least some extend when doing this. Cause this is what you do during lift of at the moment of full body extension. My RAD takes this into consideration.
Because the center between your feet remains the same (+ when descending you should be dropping your heels in steep and techy parts).
@@IDoBlues This method ist not (just) about descending. It is about maximizing your ability to input forces into the bike using your body. During an aggressive lift off, a skilled rider streches his ankles as he streches his entire legs and body. A to short RAD in that situation means, the rider can't get into full body extension like this because he needs to reach down with his hands.
@@danielhamann5552 I agree. I think you can safely measure flat-footed....like the average foot position...because you are in constant motion.
great vid bro. i keep telling people that their bikes are too big!! and cranks, omg.. "so we will put 170mm cranks on both the Medium, and the X-small.. what could go wrong?" - almost every big component maker out there..
me being right in the middle of most bike rec's @ 66" tall, i prefer to size down. my ideal reach is around 425mm and this isnt a rule always, as one bike is 420 and feels great while another is 453 and feels almost identical. STACK and stem and STA all play a role. and fwiw, most industry sizing standards are useless.
i have an enduro rig with 155mm cranks and they are the most efficient of my 4 bikes, two others have 160 cranks and i can really feel the difference (30" inseam).
*edit: i almost forgot!! if you consider MX and the fact that foot pegs are centered.. using shorter cranks on enduro and DH bikes place your feet closer together towards that center of BB, and it's quite interesting how this plays out. more control. easier whips. more steez. facts!
I don't whip, but like my stance on the descents with right-sized cranks (155 for me).
you viewers should keep in mind/be aware that for every 10mm they lose in crank length, it's equivalent to 3 teeth on a chainring. so running my 160's i went with 30T on all my bikes. close enough...@@IDoBlues
Just discovered this video. I had question. Do you calculate your height with your riding shoes on?
Yep...with riding shoes on.
Great tutorial! Out of interest, what size is your Orbea Rise? I'm 1.7m, similar to your height. If I look at Orbea's sizing chart, based on a personal reach of 434mm, I could fit on a small (425mm) or medium (450mm)? I currently ride a Scott Spark small which has a reach of 403mm with a slightly longer riser stem than stock, and without finding it cramped. The Spark does have a slacker seat angle than the Rise. Spark RAD is 82cm. My personal RAD is 78cm.
Thanks! I ride a medium Rise. The reach was 450mm stock, but I've converted my Rise to a 160/160 mullet (LOVE IT) and the reach came down to 435mm (which is my sweet spot). You can check out those details here -> czcams.com/video/oKl4exLGPxM/video.html
@@IDoBlues Nice upgrade on your rise. What is the RAD of your medium rise?
@@Stikkigloo I can't remember the exact RAD measurement, but I think it was 10-15mm RAD+ for me.
Hi there, I am new to riding. I received a mountain bike as a gift from a dear friend, (Giant Revel Aluxx 6000 / Diamond frame L, 29) and I will use it mainly, almost exclusively for urban riding. I am also 5'7'', and even though the frame is an L, I am trying to adjust it to my size. Do the methods described in this video apply for this use as well? Many thanks for your video and any advice would be most welcome. Cheers from The Dominican Republic :)
This sizing video is really looking at gravity-based mountain biking. I'm no expert on urban riding (ha, I'm not an expert at MTB either....just a bit obsessed). That bike does look a bit big for your height. You can try shortening the stem and then see if you are comfortable riding around town on it.
Crank length may depend more on foot size than on inseam; I personally know guy taller than me (180cm+) with super small feminine- looking foot (maybe US size 10 or less).
I disagree there.... especially with the trend to set the spindle more centered under the foot.
I have reach of my height times 2.6 instead of 2.55. 470 instead of 460. i do feel the bike a bit long for me, and sometime my left hand go numb on long flat sections. I shorten the stem, rotate a little bit the handelbar. any other suggestions avoiding the numbness ?
I had similar numbness. I switched my bars with 8 degrees backsweep to bars with 12 degrees backsweep and the numbness is gone. I now ride those bars (SQLab 30x) on all my bikes.
My rad matches my bike's rad and it fits like a glove. But it's got short chainstays and less travel than I want. So, I'm in the market for a new one with more travel but with so much of the selection online and not much available for testing, I'm wondering if anyone knows a formula to figure out a bike's rad based on its other numbers (geometry).
It's impossible to calculate the true RAD of a bike from the geo numbers like reach and stack because the cockpit setup comes into play (stem, risers, bars). You could estimate it using the Pythagorean theorem (reach & stack), but it'll be less than the true RAD.
What do you think is the better adjustment:
Spacer height
Stem Length
Bar geometry
When trying to fine tune R.A.D.
It depends. Adding spacers will also increase stack and decrease reach. Adding stem will increase reach & RAD. Using bar rise can increase RAD & effective stack without altering reach. Increasing bar backsweep can decrease RAD & effective reach without adjusting stack.
I think the first step is to get the bar backsweep that works for you. For me, 12 degrees works sooo much better than 8 or 9 degrees (but everyone is different). I also like to make sure my effective stem length (actual stem length with backsweep taken into consideration) is about 20-25mm for handling dynamics (all my bikes are consistent on that). So I don't use that to adjust RAD. So I guess for RAD, I'd play around with bar rise and the # of spacers.
I lean towards high effective stack and as close to an effective reach of 435-440mm as I can.
According to all these things I should be looking for a bike with a reach of approx 420 but because I have long arms my rad is only 720mm. If I used the RAD measurement I think I'd be on a kid's bike.
Ya, if your arm length is on the far end of the bell curve, using RAD gets iffy.
Is the idea and measurement for RAD for the casual rider or can it apply for a racing bike?
Oh man, I wouldn't take the RAD measurements for racing (except maybe Enduro) without more research & testing. Maybe it applies, but that's way out of my wheelhouse.
@I Do Blues luckily, I race amateur enduro. We have similar body RAD at 770mm but, my race bike measures 840mm. I do enjoy the stable downs, but I lose it in corners and switchbacks.
@@cisdix Jack Moir sizes down on the tight tracks citing that very reason. Ritchie Rude uses RAD and races with a shorter relative reach than most.
The top tube distance is irrelevant for descending? I'm buying a core 2 capra with a smmaler reach of 427 compared to my bike 430 my rad is good at 425 but the top tube will go from 610 to 563. So the bike is getting longer and bigger but the top tube is getting a lot shorter. is that a problem? important? I want to jump and ride DH
Focus on reach & RAD (which takes stack into account). Top tube length doesn't really matter.
@@IDoBluesthank you!
Does frame reach formula only work for mtb? I tried it for my road bike and it's value exceeds the reach specs for all sizes... Reach on the xl frame is 50mm too short.
I have noooo idea. Road biking is foreign to me.
@@IDoBlues Hah, ok. Thanks for responding anyway.
So i bought correct bike size S, M, L vs my height from Giant chart for 3K$, but all my dimensions are off? lol what to do now
Ride it and love it!
Does the RAD calculation apply to eMTB? I’m 5’9” and according to Specialized I should ride a S3 but according to the RAD… the S3 is too big…?
If the eBike is an eMTB meant for some gravity descents, I think yes. I like slightly RAD+. I ride a medium Orbea Rise with a reach of 450mm that feels a touch too big for me. My Forbidden Dreadnought has a reach of 435mm with a smaller RAD than the Orbea (but still RAD+) and it feels better. I'm about 171cm tall (touch over 5'7).
Looking at the Turbo Levo in S3, it has a reach of 452mm. I think that would feel good being 5'9. I really like the height (cm) x 2.55 to zero in on reach.
@@IDoBlues thanks! I have long torso and short legs so the reach feels fine, just when I measure the RAD and compare to the bikes BB to bars…. It seems not right. But the S3 size feels fine and I’m swapping the bars for a 16 degree sweep. 🙏
@@wss327 oh, nice with the sweep! I went from 8 degrees to 12 after I measured my ergo and I really liked the change.
@@IDoBlues I’m new to MTB and first week I pulled a shoulder muscle and had two very painful thumb joints… learned about sweep the hard way….
Makes you wonder why they put 170mm cranks on everything, even XS and S bikes often times.
Seeing kids & small adults on XS bikes with 170 cranks kills me a little each time.
Im 5'4" and i wonder if i can get a small 29 wheel MTB
At 5'4, I'd recommend a mullet. You get the rollover of the big front wheel, and clearance & maneuverability of the smaller rear. My son is 5'4 and his mullet works great for him.
What if I have short legs? should I get just the biggest bike I can safely use?
I'd still start by looking at bikes with a reach around your height x 2.55. If your relative leg length is way off the bell curve, you might need to pay attention to standover height a bit more than most.
@@IDoBlues It seems like thats the case. I ' m 186cm male with like 83-84 cm inseam. I'm planing to buy full suspension trial/AM bike and was wondering if I should just get the biggest I can get to my inseam from safety perspective or look for manufacturer that make sizing in long/short spectrum. For example merida one fourty have sizing L for Long, but those bikes are quite bit more expensive than those with simliefied sizing like rockrider from decathlon.
No issues with assembly for me czcams.com/users/postUgkxHL1v1R3NE5x4KiYfyt8dnQmyNYz7qi5L but I could see where some might benefit from using an experienced bike assembler/mechanic. I'm an older rider starting back after a 10 year break. This bike exceeds my capabilities and has been easy to get comfortable riding. I'm mostly on easy trails with almost no street riding and have not been disappointed with the performance of the bike. My fitness level is far below what I previously rode with and because of that the mileage is going on the bike slowly. While I'm losing weight slowly, the bike seems to tolerate my 220 pounds just fine. The bike has been used by several family members ranging from 5'5" - 5'9".
At 5'4", I'd start looking for something with a reach of 415mm or so.
I just bought a new bike and I hate it. The store never fit me properly and now I can't return it.
Ah, that totally sucks!
The best I can do is lengthen my stem but I don't want that to mess up my steering, that or sell the bike and cut my loss 😏
@@hedsy You could try higher rise bars and/or extra spacers to see if that helps (and might have less effect on the steering).
@@IDoBlues honestly, I might just cut my losses and sell the bike at a discount instead of sinking more money into it and still being disatisfied. Then I'll find somewhere that can actually help me fit a bike properly. A costly lesson learned as I know literally nothing about newer bike geometries and I'm still learning. Everything has changed so radically in the past 10 years. Your video has helped a lot though! Appreciated!
But I've seen plenty of very good or experienced riders who say they don't subscribe to the Lee McCormack theory of bike fit.
For sure. Some absolutely like longer reaches. I definitely like RAD+ over RAD or RAD-.
@@IDoBlues Yeah if I look at an Occam (I believe same geometry as your Rise) I'm right in between sizes M and L at 5'9" according to the manufacture (actually they claim the large can start at 5'7" witch is a bit small IMO).
My rad is almost exactly 32" or a touch over with my riding shoes on. Adding on some length and height to the stack and reach I guess I could really make either a medium or large around that 32" length after solving the Pythagorean theorem depending on spacers, stem, and handlebar sweep.
Obviously both of those would still feel different because the difference in parts listed above, wheelbase, weight and etc but I guess for me it does fall sort of in line with what the manufacture is saying.
If all I do is measure height 175cm x 2.55 the estimated reach is just under the medium's 450mm which could be made to work just like 474mm large.
determining the correct reach by multiplying your height in cm by 2.55 is very good way to buy a bike that is too short for you. Trust me, I have did that and it was a very costly mistake.
Works like a charm for me. But ya, just a starting point....everyone is different.
@finroddd how would you advise finding correct reach?
@@hannahjm93 I trusted a manufacturer recommended size just once and it was correct. After that I am using that reach as reference. Also it is very important to consider top tube length - it is the leading measurement when pedaling The reach is important when you riding standing on the pedals. Slightly longer reach works better for me.
@@finroddd I'm new to the sport and really finding it difficult to find used bikes in my size (I'm 5'3) so I've ended up with a hardtail thats too small (XS Trek Marlin) and a full sus thats too big (Medium Merida one sixty). I can ride both so they will do while I keep looking for a better fit but I only got the full sus recently, only done 2 rides on it and was surprised to find it felt better than the XS. I had in my head that I'd be better off on a bike a bit too small than a bit too big but once I got used to it the larger bike felt closer to what I should be riding. On the Marlin I keep getting neck/trap ache which I think is from me shrugging my shoulders constantly to account for the short reach. I didnt have that at all on the Merida.
@@hannahjm93 looks like your size is S. Check the reach on your recent bike and compare it with the reaches of the XS and the M.
A ton to digest if you’re not an engineer.
Only degree required is a Bachelors of Bike Nerdery.
@@IDoBlues I still don’t get it lol I’m sure it’s my brain density. Is it the rad? Is it the reach? Is it the measurement from the pedal shaft to the midpoint of the handlebars? Lol
@@Lion-qi8ej When in doubt.... Reach = height (cm) x 2.55!
another movie that caused problems for stores. Did you know that crank length do not depends only on standover? This movie causes more problems than good
Tell me more.
What's this "bell curve" people are talking about? 🤔
People with significantly longer or shorter arm spans than their height. Most people have arm spans that are pretty equal to their height.
6 foot 175 mm
over 6 foot 4 180s when you hit 50 years old go back to “little guy’s cranks “ 170mm the same as a 12 year old bmx champ. this narrator says “if i was 6 foot “ lol . Little guys go to great lengths to discourage 177mm cranks.
Yup
According to suggested way to measure your “rad”, people of the same height but with longer arms should buy smaller size bike? It sounds illogical.
Ya, it's bell curve. Most people have an armspan close to their height. Using the reach formula, you can zero in on the frame size, and then fine tune the cockpit based on RAD. For the people with exceptionally long or short arms compared to their height, using these general guidelines might not be as effective.
@@IDoBlues for sure this RAD measurement technique is very beneficial; it has limitations & applicability too, if you want bunny-hop higher then go with small BMX, if you want to ride faster then go with longer road bikes, etc.
And don’t forget to add pedal thickness to calculations, plus foot size… for example, with my arms spread 182cm, I need 780mm - 800mm wider than average handlebars; but with my RAD 810mm I need smaller reach. Smaller reach, with wider handlebars, isn’t it illogical?
A little bit frustrating because I just bought size L mountain bike with reach 860mm. Maybe changing handlebars will set it properly; factory handlebars are 750mm 7 degree, and I ordered 780mm 12 degree; I believe it will decrease RAD for about 2cm - 3 cm and will make it more ergonomic.
@@TPITEOTG Ya, I think it's OK to separate reach from bar width a bit. But ya, the long arms/shorter RAD is weird. 750mm bars sound too narrow for you. That's what I ride and my wingspan (and height) is 171mm. I really liked moving to a 12 degree backsweep from 8. Hopefully that works out for you too.
I turned upside down factory handlebar and stem, and moved washers from bottom to top, and RAD changed: it was about 860, and it is 810 now.
The RAD number is total BS. You can literally swap the REACH and STACK values of the bike and get the same RAD number.
Swap the reach & stack? RAD looks at the combo of both (and takes cockpit into consideration).
@@IDoBlues Yes, if theoretically two bikes would exist, one with 450 reach and 530 stack and the other one with 530 reach and 450 stack, they would both have the same RAD value (even with cockpit taken into consideration it would not differ much). If you look at the bike from the side and make your BB a center of the circle and you take RAD value as the radius, you divide the circle in 4 quadrants, you can basically get infinite points of contact on the circumference of one quadrant with the RAD staying the same. Could you ride all of the variables of the bikes?
Also, where do all the multiplying factors used in your formulas for the reach, crank length and handlebar width come from?
@@krneki111 RAD let's you get into the ballpark of the reach & variables.
The multiples come from researching recommendations along with trial and error. Lots of inspiration from Lee McCormack on RAD & reach. Handlebar width is discussed all over. Crank length is a hot topic these days with people starting to realize 170mm doesn't fit everyone (especially when taking descending as the main interest).
@@IDoBlues I am actually really interested in a source of these multiplying factors to get the reach, cranks length and handlebar width. Is there any peer reviewed research behind it or just one individual dividing their preferred reach/crank length/handlebar width with their corresponding body measurements?
@@IDoBlues As I have said before, if all you have is a fulcrum (BB) and the radius (RAD), there is nothing you can learn about how long and tall the bike should be for you as the data lacks some reference. A lot of different combinations of stack and reach values can produce the same RAD, wouldn't you agree? It is nothing more than a Pythagoras theorem with c2 being RAD and a2 and b2 being (interchangeable) variables.
Also, is there any peer reviewed research behind these multiplying factor formulas or are they a product of one individual measuring their preferred reach/crank length/handlebar width and dividing them with their body measurements?
I, for example, am a relatively proportionally built 194cm individual with a slightly longer arm span of 203 cm. These multiplying factors put me on a 495mm reach bike with a handlebar width of minimum 850mm and a crank length of 187,5 for enduro. Not so plausible, right?
My RAD is like 110mm short of the RAD on my bike but my bike fits me just fine wtf lol?
serious wtf
@@IDoBlues yeah man. got the trek roscoe 9 size M, im 169cm. Reach works out to be 430mm and bike sizing chart recommends 440mm for size medium, so 10mm short there. My RAD is 735mm and the bikes RAD is 850mm so actually 115mm off. Bike feels awesome though and im not new to biking so i'd know if things weren't right. If i had of gone with the size small the reach would've been 20 mm off, but probably would've had my RAD closer to perfect. Just food for thought anyway, very strange lol