Mountain Bike Sizing and Fit Master Class

Don't buy the wrong size bike!

0:00 INTRO / Comments
2:44 Commencal's new size chart?
3:11 Why sizing charts are bullsh*t
5:15 Why MTB sizing is important
8:09 Mistake #1
10:04 Lesson #1
11:04 Mistake #2
14:32 Lesson #2
15:15 Mistake #3
18:25 Lesson #3
18:42 How to actually size a bike
20:10 Mistake #4
23:27 Fine tuning front/rear balance
25:21 Fitting for your body
26:41 Picking a new bike
29:38 Stem Comparison Tool
30:46 Measuring your R.A.D.
31:48 Measuring your bike's R.A.D.
33:34 Summary of steps
34:39 Note for Beginners
35:38 OUTRO
36:31 BONUS RANT

Tools:

Reach and stack based sizing for mountain bikes:

[thgughy]

Great info, worth watching the whole length to fully understand the reasoning.. thank you for sharing your experience!
I'm way shorter than you, but in between sizes.. The struggle is real, and I too get crazy with numbers (probably too much). Now I've finally ordered a new bike but I still have the feeling that I haven't done all the necessary calculation and I should have gone one size up We'll see!! 😂

[Palpac]

I love discovering videos like these after spending thousands of dollars🤣

[LifeOfIvyQuinn]

I know this video is 3 years old, but as someone just getting back into riding, and having watched many videos about "bike fit", this has been the most thorough, and most helpful video on the subject. You answered several questions that none of the big channels did, and even answered questions I didn't know I had.
Thank you, so very much for taking the time to put this together and put it out here!

[fixedrider]

Your honesty and humility is very refreshing. All of us in the "in-between" range on sizing thank you, especially us old dudes who prefer riding in relative comfort.

[Whoadayson]

This may be 3yrs old but wow, it helped me alot and now I know I barking up the right tree as I ordered 'dialed' just a few days! Great info. Thx

[dongoat]

This video needs more recognition thus preventing people (like me) to feel very queazy thinking about spending thousands of dollars for a bike that doesnt fit. That RAD explanation and triangle calculator was helpful and gave me confidence on the bike that I just bought. Great video!

[RACCHIETTO]

Man, this is an eye opener!! I was looking for a new bike and i was actually comparing the RAD measurement between my bike and other ones, but i didn't think this was actually proven bike fitting science. I just took the measurment you mentioned in the video, no wonder i felt so balanced on my bike, my RAD is 78~cm, and the "bike's RAD" is 80~cm, i still feel a smidge light on the front in fact i wanted to lower the handlebars by 2 cm, which would actually be spot on 78 cm RAD.
I'll try that and we'll see how i feel on the trail.
Thank you so much, i didn't think i would sit through the whole 42 minutes, this is gold.

[PrisonerNChristJesus]

Great job putting this together and helping people to get a better understanding of what kind of a ride the industry takes us on. Lots of factors to consider and you covered all of them, however there is another factor that I’m not sure how to quantify but would like to try to explain …

Living in Maine, we are so jealous of the kind of trails that the industry promotes in their sales videos and of course in the high speed flowy northwest Midwest regions. After all, no one wants to see our messy twisty accelerate just to brake to slow roll for a nearly 180 switchback, most of our trails would make for boring video for sure.

When it comes to sizing, we definitely need smaller and more nimble than the BS size charts give us as average 5’8” males can’t sail these massive boats through the switchback jungle.

Everything you taught us in your video is spot on but the type of trail certainly plays a part in whether someone may want to go RAD PLUS (speed) or perhaps RAD MINUS (medium speed maneuverability).

Trail factor?

[adibee]

So Glad i found THIS, BEFORE pulling the trigger on my next buy!!

[dannyrie]

It's funny because I think with modern bikes, the RAD method generally shows that bikes that ppl are getting are OVERsized, not undersized

[mrlaw]

Excellent. Since I lived in Soquel, you caught my attention with the trails. Lots of trails around there, and then over in Nisene Marks State Park.

[ssmith]

This was really helpful -- thanks! I'm 1m80 / 5'11" and so therefore seemingly always between sizes (M & L). This has helped me ignore the sizes and look at the geometry charts instead.

[willstuart]

Thankyou for sharing this - very helpful! What is your stack to reach ratio?

[pborgix]

Thank you for making this video. I have been looking for this info online for a while and didn't find anything so helpful and clear as yours. Its really good. I really appreciated it.

[colby.goettel]

Thank you! This is exactly what I needed. I'm like a sized up version of you (6'6", 33" inseam, +3 ape index). Thank you for taking the time to put this information out!

[EarlLewis]

So glad you made this video. The problem you experienced is not exclusive to tall riders. I'm 5'7" and just had a similar experience with a size M that I ordered online. This was the smallest bike the company offered and it was just too big for me. I could tell as soon as I got on it. And riding if a few times helped sort that out for me. That's when I started looking at bike fit a lot more closely and came across the Lee McCormack RAD sizing method. Then I started looking at geometries a lot more closely and found out that I would probably be a lot happier on a bike with a much shorter reach (should be 430 or so and the M that I had was 471).

When I talked to the company about the bike and fit they were certainly understanding that the bike didn't fit great and they didn't want me on a bike that didn't make me happy. However they sort of poo-pooed the RAD sizing methodology and threw out the old trope about RAD not being an industry standard, yada, yada. I think this is going to catch on more and more, with riders, but doubt that bike companies are going to take it too seriously, ever. It would be nice if they did, but like Lee and Alex said in their video (and you repeated) you couldn't ride some bikes in ANY size. That's bad news for bike companies and they definitely don't want to hear that about their bikes.

Anyway, thanks for the video and sharing your experience and journey. Good info all the way around.

[Eric-xxmb]

Ironically, the guy who invented RAD, LeeMcCormack, has said on video that 9 out of 10 riders are riding a bike that is too large. It's ironic that RAD actually led you to a bigger bike as that's not the norm, but, then again, you are a very tall person.

[HeretiCflow]

I'm 185cm (6ft) I built my META 29 last year in size large. I didn't even think about bike sizing, never heard of "RAD" or anything. I just went by body height and gut feel and so far I guess I got lucky, because it feels great and got all the grip I'd ever want. However, all this information I'm now receiving makes me think, maybe overthink. And I think that's another lesson here: If you have a bike that feels great, "don't fix what isn't broken".

[Woodflooralchemist]

I’m 16 min in right now. This is greatly helpful. I’m currently looking for my first bike. I’m very unsure about frame size and wheel size.

[lonewanderer]

Rezzing this vid. In 4 years a lot has changed but this is still great info. My stats for reference:
Bike size: L
Bike OE stack: 643
Bike OE reach: 463
Current reach: 450
Bar rise(S&M bmx race): 123mm
Current RAD: 900
Height: 182 cm
200mm dropper/170mm crank
CSL: 455
WB: 1250
HTA: 65
Fork: 140mm

Bike feels perfect. I could go a size down on the same frame and be fine but the added WB is really nice.