Modern bike sizing (aka am I buying the wrong size bike)

I don't see it as "these damn bike companies are moving away from me" as much as "these bike designs are evolving and these bike companies find [this] sizing to work best for people of [this] height range who ride the bike [in this sort of way]." It would be REALLY against the bike companies' best interest to inappropriately size their bikes. I trust the engineers, designers, and product developers to know more about bike design than I do. What's something you're VERY good at? Something you're an expert at? Would you say a hobbyist would know more than you in that field or would you ask them to trust you? How often would that sometimes-hobbyist be better-informed and more-considered than you are in the details of your expertise?

Let's see what the brands have to say:

According to Commencal, you're at the top end of the medium size or the bottom end of their large size. At that point you're selecting a bike to be a little more maneuverable or more stable. Which do you want more? According to Trek, you're right in the middle of their R2 size.

So I guess you have your answers. They recommend the smaller size for the Trek. You seem to think you should be on that same size. I wouldn't overthink it and just go with what they recommend...which happens to be what you thought, too, so it'll probably fit perfectly!

I didn't have THE SAME problem but mine was similar.

I was pretty sure the size of bike I was being recommended (by both the brand's website and the bike shop) was incorrect and that I should size down. And then I happened to end up in the same city as the bike brand's headquarters when visiting family so I scheduled a 30-minute sizing fest of a few different bikes in different sizes with some different stack heights.

Turns out those guys were right. The larger size bike ended up being better in all ways except the "ease of bunnyhop" way. A shorter front end and shorter rear end DOES make bunnyhopping a little more intuitive for me...but less than 6 months later and I'm hopping higher now than I was on my old, nimble, very-easily-to-hop bike anyway. Cornering, longer distance pedaling, shorter sprints, rough terrain, manuals, endo turns, and drops are ALL easier/better on this bike. Is it possibly only because the bike is fuckin' awesome? Could be. But I also think a better-fitting bike helps those skills quite a bit. 

It looks like you have your answer: R2 Trek Session! I expect a full review of how sick that new Session is when you get it out on the trail!

Sorry to say but bike industry as a whole is anything but bunch of knowledgeable people with only riders best interest on their mind. We were seeing incremental changes for the sake of milking as much money out of riders as possible over as many iterations of same old things as possible over and over again. It's fair to say that a bit of cautiousness is appropriate. Is the geometry at the moment more or less stabilized and in a good place? Likely yes. But it took a lot longer to get here than it should have.

Id rather now see well thought out bikes that didnt have QC drama... alloy bikes that are actually aligned etc than us sold on new 'geo changes' or new damper's(that are rubbish because our bikes are to light) etc
suspension parts still has the most benefit, going from a tk silver to a performance is massive but the jump from a performance to a GX2 is only a small amount that most people cant even tell. going from a dpx2 to a coil is a massive difference, dpx2 is a great progressive shock(despite its very small internal shaft issues) while a EXT etc is a very nice ride.

We mtb'ers get very caught up in the latest stuff, Like an XT drivetrain still performs and is reliable but is cheap vs an XX or XO Transmission at extremely costly, offer next to no perfomance gain but a cost a sh1t load.

To add to my suspension point, brakes aswell, we still cant figure out a nice simple setup that provides immense power.. Like why does setup and bleeding MTB brakes have to require more than 2IQ.

I agree with you in most bike-related respects.

But I don't think sizing recommendations are included in that.

They definitely make a million different angle/feature/layup/etc. "improvements" in the hopes you'll buy their new bike. That benefits them, though. If they can talk you into a 63.5º head angle this year and come back next year with a 64º angle but higher stack, they will.  That's pure and simple bottom line consumerism stuff that I hate but is in no way exclusive to the bike industry.

Bike fit/sizing, though? That stuff's free and telling people the wrong info isn't going to make them buy your "new and better fit" bike next year. It'll just turn them off from your company and your bikes. You'll never gain a lifelong customer by selling them a bike that's too large (or too small). You're making the different sizes of frames either way; directing your customers to the bike size from your already-made bikes that fit them the best is purely beneficial and anything other than getting someone fit to the bike from your lineup that ideally fits them risks their purchase and their brand loyalty.

One person who should be on a medium but a chart recommended a large so they bought a large is a person going online and/or telling their friends at the Tuesday night races that the bike is wallowy and unresponsive and hard to corner and jumps like shit and they've made every tweak they could but the bike sucks worse than their bike from 4 years ago and they're looking to sell it immediately and get a different brand because that brand's bikes all use the same design language/principals and all probably ride like shit. If that person has a large friend group or a loud voice you've potentially lost 10 to 30 bike sales based on that negative experience and that person's willingness to talk about it. If it happens to be the fast older guy, his kids never ride your brand, their kids never ride your brand, their riding friends get steered away from the brand, the riding friends' kids don't get the brand recommended. All because the person was recommended the wrong size; a thing that costs the same to do right or do wrong?

The same person on the medium size bike would say it's lively and maneuverable and easy to corner and jumps well and they're so stoked about the bike and would probably be open to adding another bike from them. No difference of costs to the manufacturer but it's now created someone who's much more likely to recommend that brand and buy that brand again.

I think you're 100% right to be suspicious about the things companies do to try to talk you into buying their stuff. I also think that those companies want you - if you've decided to buy their stuff - to have the product that most ideally matches your needs because a happy customer adds additional future purchases and an unhappy customer reduces future purchases.

I appreciate the energy and time you spent writing that post and there is large part that I can agree with. What I think is happening in the past 5 years or so is bike geometry and sizing changed so much its like starting from the scratch and everything person riding for the decade before should be forgotten. And people don't like change, and especially big one. Other thing is if you are riding bikes for lets say past 20 years, there is no chance you haven't adapted to riding bikes that simply are too small for you. Fast forward to 2025, now you have recommended bike that is easily 100mm longer in wheelbase, head angle 3degrees slacker, reach 50mm longer etc. It's basically a different beast altogether. And it's not worse most likely in any way (weight maybe if that is still something you care about), but you cannot realistically expect to adapt to it over a day or two of riding, good setup from the get go will help you get there faster for sure, but you sometimes have to invest time and think about how you ride the bike for some time to start reaping benefits. If you ride it in the same way as you rode the small one, you are not going to have a good time indeed. Overall, I think ditching the sizing s,m,l etc for S1,2,3,4, or R1,2,3 or whatever is good effort to avoid people taking what they once used and applying it somewhere where it's no longer relevant. With short seat tubes and decent seatpost insertion depth, it's not impossible to ride 3 different sizes and pick the one you prefer overall, not the one you can actually get the saddle low enough for dh riding like before was often the case.

I had a lot of struggles with this and quite frankly rode bikes that were the wrong size for me for five years. I'm 6'2" with way longer legs than arms, like abnormally long legs. I had a 2016 Hightower in XL with 467MM Reach and 66.4 degree head angle (overforked to 160MM) that I loved. 

Then I went to a Megatower XL with 490mm reach and 65 degree head angle that I absolutely could not get along with. I thought it was just the fact it was a bigger travel bike, so got a Stumpy S5 with 500MM reach and 65 degree head angle. Again, I still hated the bike and couldn't turn it. 

So I finally bit the bullet and got a Large Spectral with 480mm reach and 64 degree head angle. That bike was honestly pretty dang good, but I still felt like it was hard to weight the front wheel because it was so slack. I now ride a large Pivot Switchblade with 480mm reach and a 65.2 degree head angle and find it perfect. I can finally get my weight on the front wheel well, and can still turn the bike and make it feel agile in tight turns

What I ultimately concluded was that the measurement I needed to optimize for the bike was front center, not reach. Front center is influenced by both reach and head angle. I was making the impacts much worse when I moved away from my Hightower by not only increasing reach, but also getting slacker, increasing front center and making the front wheel further away from me and harder to weight. So this means for slacker and longer travel bikes, you need shorter reach to keep the front center the same.

The way you can counteract this is with stem length. For the most part, any stem between 35mm (maybe even 32mm) and 50mm will handle totally fine (heck, you see DH racers on 55mm stems). So on a bike like the Pivot Firebird, which is a 63.5 degree head angle, I'd probably want to run a medium at 465mm reach and a 50-55mm stem to keep the front center and total wheelbase in check. Whereas on my Switchblade at 65.2 degrees, I run a large at 480mm reach and a 40mm stem.

This front center balance is why I believe many of the EWS racers are on frames that we deem too small for them but longer (~50mm) stems. Like when Jack Moir rode a size small (?) and how Ed Masters and Matt Walker both ride mediums.

lol I was on a medium firebird of the last gen. ran it with a 50mm stem and 35mm bars. struggled with front end grip from day 1.

got the new one in a large and i'm so much happier. haven't touched a thing. 

(6' tall for reference)

At 6' 1", I am commonly between size L and XL. My last bike was a 2017 Commencal Meta AM size L (27.5,) and it seemed about right. However, there were times I felt like I was hunched over on it, especially while climbing. The stack height seemed pretty low, also.

I just purchased a new Meta V5 and decided to go with the XL after test riding one. It's true the bike is longer, but the seatpost angle is steeper as well, so the reach actually feels about the same, size to size. Between the larger size and the 29" wheels, my XL felt gigantic for a short while. However, now it feels like home and the old bike is dinky. "How did I ride that thing?" is what I'm thinking when I roll it around the garage. 

Some rider background: I have shorter legs and a longer torso, so I want more room in the rider cockpit. I also prefer to smash and roll over things and I don't care if I give up a little playfulness. I'd prefer to be overbiked than underbiked. 

If you're between sizes (as it seems) I think the most important decision is this: would you prefer a larger, heavier, less-affected chassis, or a more nimble, playful, active chassis? 

Perhaps we’re at a point that the sizing sticker on the frame is less helpful than ever. It seems more up to the consumer to read the geo charts and make decisions from there. When I bought my last DH bike, I sized up thinking I’d like a bit more reach than my previous one. I got amazing straight-line speed and confidence in the gnar, but it came at the cost of cornering, the ability to change lines quickly, and an overall sense of playfulness, and at times I felt like I was simply holding on instead of actually being in control of it. I unloaded it after one season and got back on the smaller size; the results are night and day. It’s all about how and where YOU ride and the feel you’re after. Good luck!

I work in product development and a lot of times the product owner will order features or specifications that are either unnecessary or not the best solution simply because that’s what he thinks the market wants.

Also I’m just now building up a Raaw Madonna that is a size and a half too small.

"This front center balance is why I believe many of the EWS racers are on frames that we deem too small for them but longer (~50mm) stems. Like when Jack Moir rode a size small (?) and how Ed Masters and Matt Walker both ride mediums."

BINGO. 

Pretty tired of hearing the whole they don't need stability like us 'mortals' crap like its that cut and dry and simple. Although there are many other factors that come into play and I am sure getting the wheelbase of a Medium is a lot better than an XL around the tight jank, I think a lot more of it has to do with F to R balance on the selected sizes chosen to race. I mean go calculate the ratio. for all the top guys... theres something to be seen there. Years ago, I remember Richie talking about sizing down for front end traction. Yetis are notoriously unbalanced in what would be his company recommended size yet the jump to his size brought significantly more balance and traction to the front. The types of trails those folks ride, its pretty crucial to be able to weight the front more when they need to. 

I do not want to type too much or rant but see eye to eye with your thoughts.

Speaking of in between sizes... I feel this at 6'2". Its wild that XLs always felt too small and in a short timeframe have jumped to I think too big. Unbalanced and some still lacking proper head tubes, stacks, and that good stuff. Its honestly making me look at larges more than ever which is whack. Some of these companies like Raaw with way higher stacks and decent chainstays in L look more appealing than XLs and being overly stretched and imbalanced. Be fun to mate a XL rear to L front Madonna V3. Dang good proportions, nice stack to help fit, decent reach still and room to extend with headset and still keep balance. Could be a nice fit. I also look at Forbiddens because of balance (THANK YOU FORBIDDEN!) but get torn between XL and L because of stack and reach preference throwing me between the two(wheelbase massive too). 

I understand the pain now of you medium large people haha as it used to always just be an obvious buy an XL. Now I just want that balance yall have been enjoying in the main engineered size for all this time.

the bigger the size these days the more the chainstay should grow yet manufacturers still think one size fits all. my old banshee titan v3.2 was way more balanced with the shorter reach yet longer chainstay than my current kenevo sl2 is. i'm looking very hard at what forbidden is doing right now as my next (e)bike as they seem to have the same thought(s)

How much of it is thinking one size fits all, and how much is figuring out the extra cost of size specific rear triangles isnt worth it for the few geometry nerds that would buy the bike under said condition ? 
 

from leverage changes all the way to packaging and shipping... Soon those rear centre fella's will be asking for the bike to ride the hill for them. some of those bikes are already a bus

Surprised no one has mentioned that companies are building DH bikes for RACING at the WC level.  Look at how World Cup tracks are: fast, wide open and even the tech sections are designed to be hit at speed.  If that’s what your riding probably go with the manufacturers size.  If your hitting jumps a lot, steep slower speed tech, not trying to beat the clock…well maybe down size a bit.  That being said I think you can adapt to whatever size you get if it’s the correct size and have a good time.  

Really curious about your Madonna - how tall are you, what size did you get, and how has it worked out?

I’m currently considering the same thing. A tad over 6’ (long arms, short legs) and thinking about a medium Madonna with 455 reach and +5 chainstay for that sweet, sweet 1.78x FC:RC ratio and manageable 1,253 wheelbase. 

I figure with the tall 650 stack and a 45 stem, that would actually be a reasonably spacious cockpit. Currently on a 480 reach with 636 stack and a 31 stem, so effective span wouldn’t be wildly different. 

Mostly concerned about the short 605 ETT while climbing seated, but could always get one of the rearward offset clamp heads to stretch the cockpit if needed.
 

I'm 197 cm and got a large Madonna and I have set it up with the high bb shock mount and long chainstay option. it's been great, but now I haven't ridden for two months, since I dislocated my shoulder trying to go faster than I should have on a blown out track.

This is the first enduro bike I've ever had where I haven't pushed the saddle all the way forward, its roughly in the middle and its fits great.

I could see that a longer bike would be advantageous on the very fast and wide open bits, but the smaller one feels like an advantage on the really steep and tight and awkward parts.

I'm 5'11 with long legs and a neutral ape index, and I've been thinking that my ideal bike might be a medium Kavenz VHP16 with +30mm chainstays and a 50mm or so riser.  I think the 126-127ish wheelbase at sag would feel manageable through tight stuff, and the seated pedaling position can be addressed through stem length and the seat rails if things feel feels cramped.  

I have three small kids, though, so this is almost certainly an academic exercise, sadly...

Interesting, thanks! Sorry to hear about your shoulder - dislocated mine, broke the socket, and was off for >2 years between initial misdiagnosis and surgery delays, so I definitely feel your pain. If it helps, I had a Latarjet and now that is my better (stronger/more stable) shoulder!

What length stem are you running? If you're 197cm (nearly 6'6") and feel reasonably comfortable on a large with a 618 ETT, then it sounds like I should be fine on the medium's 605 ETT at 184cm (6'0.5").  

I've been using both 45 and 50 mm stems, both work fine.

To me the bigger issue with the reach sizing is how it relates to stack and what happens to the bike if you run a riser bar to 'fix' the hand positioning.

You can, effectively, push the reach out more and more and more along that plane... But there is a limit to the stack height, even though I don't know anyone who doesn't need to cut a stock fork? Maybe like the longest version of a Nicolai/Geometron or something?

But we see this in the stack reach ratio as it goes through the sizing. The percentage increase from reach to reach always outpaces the increase from stack to stack. So generally XL+ riders get screwed over.

And for all I know, maybe some XS riders feel like their bikes are difficult to weight the front or climb or something... I wouldn't know, tho I'm sure it's fine.

But ya I want a stack/reach ratio above 1.3, honestly closer to 1.4; and its something I've liked about the new Stumpjumpers I tried. And it may be part of the reason when I demo a bike (where I cannot adjust it/put on new bars) I prefer mediums to larges. Even though it doesn't feel tremendous downhill in the rough stuff at speed in a straight line.

And having put a ridiculous bar on a size large to 'fix' the hand positioning in the past... It's BETTER but to me it's still not the same. As someone who is 6 foot with shoes on, I currently ride a medium. I love it for all around riding. I obviously wouldn't mind a large (with riser bars?) for the rough downhills, but I don't like it everywhere else. Effectively making me a tweener size. That said, when a brand makes a quite long 'medium' with an actually tall stack height, that bike basically becomes perfect. Nobody is quite making a 'short' large right now, and if they do there is a fair chance they don't have a healthy stack height. I'd love to hear of some examples though.

As of now I am currently looking for 460-475mm reach with well over 600mm reach. Although it kinda depends on wheel size. Easy for 29 to get up there but 27 front builds really struggle to push above 600. But ya like 615+.

New Stumpy EVO doing like 470/644 for a 1.37 ratio is basically immaculate. Because the stack is so high, even the smaller 445/630 build is great. And ya know for those XL riders (i guess sadly it has no XXL) they FINALLY have a bike with a 1.3 or higher ratio, at 495/658. And they were sensible enough to not give it 435mm stays. Even if 445 is still not enough. But great builds S1-S5 in my mind. Particularly compared to past offerings.

Raaw Madonna has a 455mm reach and 650mm stack in medium. 480mm and 664mmin large.

Commencal Meta SX V5 has a 460mm reach and 638mm stack in medium. 480mm and 642mm in large.

Those bikes are definitely two options I'd be looking at if I were looking for more stack height in that enduro category. 

I wish I could afford to build a Madonna. The framekit costs more than my current bike. The rolling chassis costs more than my GF's ebike lol

The Meta SX is a great build. Did they... Not do headset routing on the SX? Cuz it looks like it has the headset 'type' for it but in product shots it's not routed that way. Such a good price/value with the base model on sale right now.

Though I think I'd still start with a base Stumpy and build from there. I mean it's actually my plan in so far as this YT has no future. If it breaks tomorrow, it's going in a Stumpy frame, since it fits.

I think they only ever did headset routing on the TEMPO. They might have done some on the ebikes as well but I literally do not look at or take notice of ebikes willingly so I wouldn't know (other people can ride ebikes and I have no real issues with 'em but I have no use for one, no desire for one, and could do so much more with that additional bike budget).

Headset routing might have also been an option on the a la carte frame-up bike builder but I don't think any of the factory builds for the either of the V5 enduro bikes got headset routing as a stock "feature."

I think those Commencal V5 bikes look sick. I have the V2 hardtail and it rips. It would be better if I'd have bought it in a better size for me (I went small thinking that it would be better for my transition from bmx through a few years of injury to mtb but I should have just gotten a medium in the first place) but the bike is super sick. If I had need for an all-mountain bike, I'd be riding a Meta V5. As it is with the riding I do in the locations I do it, a shorter travel trail bike is the only sensible choice. I was sold on the TEMPO (Öhlins build, probably) until the headset routing forced me into "100% NO." Simple as that.

^My Meta V5 has a headset that will accept routing or not. (There are knockouts, or "doors" you can use.) The frame has the grommets and I'm using those; no headset routing for me, either!

This is what I run and I'm 5 11. I'm a reasonably good rider and pretty much only ride the bike at whistler, my other ride is a mulleted spire (geo corrected with shock eyelet) which I absolutely love. The session feels good when I hammer as fast as I can go and when I'm feeling fit and strong, but on days when I just want to cruise around it feels quite dead, and honestly it's almost unrideable on "normal" trails. If I was doing a shuttle day anywhere local (cypress, seymour) I'm grabbing the spire every time. All that is to say, next year i'm grabbing something a bit smaller, maybe low pivot.