Forgive me if this is a dumbgeon level topic but its something I have wondered for some time. For MTB especially, the geometry numbers of new bikes are a big factor in the overall appeal. Head angle, reach, wheelbase etc. are some of the "directly transferable" metrics I would think people in the moto world would be keen to know when new bikes are released as they have direct effects on handling. I dont ever see that being much of the marketing pitch or info that people mention in reviews. Why?
Upgrade to enjoy this feature!
Vital MX fantasy is free to play, but Premium users receive great benefits. Premium benefits include:
- View and download rider stats
- Pick trends
- Create a private league
- And more!
Only $10 for all 2026 SX, MX, and SMX series.
The MTB industry still doesn’t know what they're doing, so they fling all sorts of crap against the wall to see what sticks. Hence the wildly varying specs year to year.
***This is paraphrasing and regurgitation of what I've heard over the years. I hope someone will come and correct any errors I've made.
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
This is all to say, it sort of renders the measurements of 'reach' or 'stack height' or other ergo numbers sort of moot. As far as wheelbase goes, two things. First, all the moto bikes wheelbase's are really close with no practical difference. Two this is also adjustable by sliding the rear axle forward or back, as well as sliding the fork up or down in the triple clamps, so all dirt bikes have essentially adjustable wheelbases.
Plus there is a lot more to go into with the manufacturing and that bicycle don't have motors and can change all the different angles of the frame much easier than dirt bikes because a motorcycle's geo is constrained by where the gas tank, airbox, exhaust, etc. etc. has to be.
Interestingly, custom suspension tuning isn't much of a thing in mtbs, plenty of cyclists with more money than brains would probably be willing to send their suspension out for a $1000 revalve and automatically give glowing reviews whether or not it's any good.
With no suspension tuning and no engine tuning on bikes, geometry and weight are kinda the only thing cycle dorks can bicker about, so the numbers recieve alot of attention.
Sag, fork height, triple clamps offset, linkage, rear wheel position, cut subframe etc. are all used to manipulate geometry.
Bicycles all use the same components - forks, wheels, cranks etc. are all universal, so other than sag any adjustments are made through frame geometry.
When I get a new MTB, I literally just adjust my levers, set my sag (with air, don't need springs) and ride the shit out of it. When I get on a new model MX bike, it takes me months and multiple modifications to get it close to where I want it.
If you offered a dirt bike with 3 different frames of varying geometry, you’d need significantly more tooling, much higher R&D costs and greater risk in clearing your inventory or falling short of demand. This would all raise costs dramatically.
Most manufactures instead meet in the middle of geometry trade offs with a do-all frame that can be tweaked with aftermarket parts to slightly change geometry. Axle adjustment, sag/fork height/springing/valving, triple clamp offset and rake can all tune geometry within a range. Even with those frames the manufacturers take different geometry approaches such that each bike has a distinct feel that can be attributed to what would be called geometry on a mtb. Yamaha and Honda both use the same basic construction for their frames, but one of them is a sharp turner with twitch and chatter and the other is more stable while requiring more effort to tip in.
A dirt bike also has significantly more parts and weighs 200 pounds more. If you want to change the feel of a dirt bike it’s just more efficient to do it with parts whereas a mountain bike is more efficient to rework through frame geometry.
Steering head angle, wheelbase, ect are all factors, but most riders don't want to know numbers - they just want to know how it handles.
I've worked with a well known Moto suspension guy trying to improve a couple of my MTB's, last one being an S-Works Epic. At the end of the day, it didn't really make that much of a difference. I could make most of the adjustments I needed with air pressure and clicker adjustments on the forks/shock.
Things are about to get weird with electronic MTB suspension. I just got a new Pivot Mach4SL with the Fox Live Valve and it fucking sucks
1) Moto has had geometry dialed for a LONG time. In fact, the closer mountain bikes have become to motos when it comes to a number of geo numbers, the better they have become.
2) Moto companies spend a lot of time balancing their chassis with respect to where the weight is located and where the rider is located. Offering geometry adjustment or sizes creates a myriad of headaches for the moto companies where each size is going to ride differently unless they go to great lengths to move the entire motor/transmission in the frame etc.
3) I'd argue mountain bike companies still haven't aligned handling characteristics to rider orientation on the bike very well. Again, sizing changes with a static rear end (usually the case) should tell you everything you need to know here.
4) As far as valving goes, its less important being the vehicle is so much lighter. Most mountain bike suspension is valved incredibly light on the compression side with the spring doing most of the work during the compression stroke. This side of red bull rampage or WC DH, this seems to work really well and most riders wouldn't get much bang for their buck with a valving change.
In fact, Back when I bought my previous MTB in 2005, the guys at the bike shop convinced me I'd hate the bicycle I was asking about... I wanted to know if anyone made a bike with a taller handlebar, longer suspension travel and more motocross-style riding position. Lo and behold, roughly 10 years later, that's what everyone is building.
Pit Row
from MXA:
Q: HOW DOES THE 2013 RM-Z450 HANDLE?
A: The RM-Z450 feels like the front end is attached to a roller-coaster track. The yellow bike can dive inside of every bike on the track?unless that bike is another Suzuki.
How did Suzuki get their bike to turn so well? We don’t really know. You would expect to find that Suzuki’s frame geometry would be as much as 2 degrees steeper and armed with less trail than the red, green, blue and orange brands, but just the opposite is true. It doesn’t have the steep head angle normally associated with sharp cornering and its trail is actually longer than the other brands. None of these numbers would recommend it as the sharpest-turning bike made, but motocross bikes don’t live or die by a single dimension. The Suzuki RM-Z450’s geometry is a mystery, even to those familiar with the art of geometry.
Interesting thing is Yamaha had (least 2016) different head angle for EU and USA versions.
He asked why people don't do more to MTB suspension - I stated many people change tokens, which has a much bigger effect on the fork feel than any valving.
On a different note, I had a top MX suspension tuner work with me to revalve my internals both front and rear. Shims. Just like MX suspension. It didn't really do shit.
I tried it on 2 bikes and 3 forks. 2018 Trek Top Fuel and 2019 S-Works Epic. RockShox RS-1 fork, RockShox SID WC carbon fork and Fox Factory 32 100mm SC. Cat 2 XC racer in SoCal at the time.
Mtb continuously gets new tech.... even entirely new designs...
Mx gets bng...
How do we fix it? Two ways... 1. Complain about the quality of the product... And 2. Stop buying new until there is something actually better than we have now
An XC bike in 2010 vs now is so different. They now have a ton more travel and slacker geometry as the World Cup XC and Olympics Courses are getting pretty damn technical. In 2010, most bikes were 26' wheels as well.
If you look at the bikes Tomac raced in the 90's vs a current bike, and then a 1990 MX bike vs. 2022 MX bike...there's a hell of a lot more similarities to the MX bike than MTB.
In the last 20 years MTB's have gone from:
Aluminum to carbon
Rigid or front fork only to full suspension and now up to 120mm of travel
Rim brakes to disc brakes
26" wheels to 29"
Edit: then again since the air volume is so low to begin with changing that probably does make a significant difference. I'm not a suspension expert I mostly ride hilly xc on a hardtail.
Mountain bikes can be made one-off custom for a reasonable price, no way we can do this in moto.
After getting back in mountain bikes after I stopped racing in 2000, it's been super fun trying all the different bikes. Honestly, it's made mountain biking more exciting for me because of how many different parts there are to try.
What I wanted to solve was the diving going into corners, and chatter from corner entrance to exit to increase traction. Coming into a turn the bike would dive, not rebound quick enough and pack...it would unload every 2nd or 3rd bump instead of every bump, therefore was never in the right part of the stroke. This started on the Trek Top Fuel with RockShox RS-1 fork.
First, we started with tokens, clickers and air pressure. After 2 separate days, we got it lightyears better than it was. From there, he went in and started messing with valving and oil. 5 days and 3 revalves later, I wasn't blown away with the results. I then got a Fox fork to try...same results.
Then, I got the S-Works Epic with Brain suspension. That thing was a nightmare to get set up, the Brain makes it extremely harsh. I got a new fork insert to eliminate the Brain, and replaced the shock with a RockShox SidLuxe to remove the brain. We went through the same process as the Trek and at the end of the day, the tokens, clickers and air pressure did exactly what I needed it to.
Idk what else to say. We tried hard to make it work. The dude saw a huge opportunity to clean up doing MTB suspension revalves, but it just didn't help enough to justify the cost it would be. He scrapped the idea after trying with a couple more people. Tuesday night races in Orange County get 800+ riders with disposable incomes and he still didn't see the value.
I think it's in part the lack of weight of the machine, simplicity of the suspension, no acceleration bumps to contend with and much less/smaller braking bumps, your body doesn't move around as much...I don't know.
Post a reply to: Geometry - why isn't it a thing in moto?