Higher stack heights. I believe that we should be riding mountain bikes in a much more upright position. We should be riding mountain bikes like Jett Lawrence rides a motocross bike. If you watch him ride, he’s not bent over very much. He rides like he’s almost standing straight up and he keeps himself in that position. It’s a much more comfortable position and it’s a position where you have more control of the bike and less fatigue while riding. It allows you to unhinge your hips, which allows more control. I would like to see companies start making 20 or 25° rise stems, in different lengths in order to get a higher stack height. Eventually frame builders will make the frames with higher stack heights. When Trek gave me the last bike, I wish an XL was available. I would have bought a Rulezman stem, where the stem basically sits on top of the steerer tube. I had to take a medium, which is my suggested size. But, I could do the same thing with a 45 or 50mm stem with a high degree of rise. No one really makes a good stem like that. Someone should start making a stem like that.
I believe that the next big change in MTB geometry is going to be…
Shawn in da Canyon
221 - 240 of 246 Posts
Have you measured weight distribution when going downhill? I suspect that on DH trails our weight distribuition is a lot closer to 50%.
Joined
·
5,815 Posts
It will be similar under a big weight shift too, like a fairly hard brake into a corner.
I think stack is also tricky when viewed just from DH perspective too as ultimately it's reducing effective reach which is probably less of an issue racing DH. But it will also reduce effective top tube length which is an issue for trail riding.
I'm trying to think if it was Minnaar whose bar to floor measurement has remained almost the same despite all the bike changes over the years? I'd have to look it up.
Definitely agree that a higher front end is more comfortable on steeper stuff. I haven't really looked to hard at Goldstone's setup, to see if he's on 29/650B, crowns etc to see how low or high his bars are to others.
Joined
·
200 Posts
You're already on a balanced bike, front-to-back ratio of 1.77. You don't need to add longer stays. The problem is many people have LLS bikes in size L or larger that have front centers that are way too long and are unbalanced. If you ride a S or M sized bike or a short travel one, you probably have always had a balanced bike. Everyone had one back when we rode 26ers cuz wheelbases were so short.
But with bikes getting longer and slacker, bike manufacturers didn't make the rear end longer to compensate. This ends up with pushing ridiculous geo like 1300 wheelbase with barely 435 chainstays in the bigger sizes. Someone riding a Medium sized bike will have an entirely different riding experience than someone riding an XL of the same bike, which is exacerbated even more when you consider someone on an XL needs a higher stack.
This is why I say proportional chainstay length should be the next big thing, like Forbidden is doing. Their front-to-back ratio is the same across all sizes. The chainstay growth across sizes is meaningful, not the pitiful +2mm that most brands end up doing, which while nice doesn't make things truly proportinal. If you're a tall rider or ride a LLS bike, proportional chainstays and a proper front/back ratio make a huge difference.
Joined
·
1,207 Posts
Sometimes I forget that people who ride medium sized frames are much less aware of chainstay length and the impact it has... because everything we've been asking for, they've already had
Joined
·
1,336 Posts
Joined
·
1,207 Posts
applaud the effort and love the 45mm stem (assuming that’s the pro taper 45)… best length
I hate to admit it but I’d struggle to run bars that look like that. I’ve got the 50 rise Title bars, they did a good job not making them not look like bmx bars. There’s only so much you can disguise with 80 rise though, ha. I guess if that’s the only option you just gotta send it.
Joined
·
1,336 Posts
That's a 50 mm stem. I feel like such a failure now 🤣
Yeah looks weird but I'm trying to brace the visual... Hopefully the handling will be worth it!
Joined
·
1,783 Posts
Very similar, I'm 6'2", not sure about my exact inseam, I wear 34 pants but I also like them on the longer/baggier side. I think the bars look fine, but we should all be more concerned with feel/function ayways. I imagine those are mighty comfortable especially with the silicone grips.
Effective reach is easily changed by switching to a different stem length.
As a personal preference I look for bikes with low stack heights and short chainstays. But, I get why some people are looking for high stack heights and long chainstays. There are some real benifits and some real negatives.
Joined
·
7,189 Posts
My XXL Megatower has a FC:RC ratio of 1.93 and I think that's about my limit. I sold a Hightower V3 because it felt so unbalanced. It was like the front wheel was just floating over the trail. It's a very real problem on larger sizes.
Joined
·
1,207 Posts
Just want to point out that you can’t look at FC:RC in a vacuum either. I’ve had two bikes with the same FC:RC but pretty significant difference in front end grip, because one bike had a longer reach and steeper head angle, versus shorter reach and slack HA.
It’s also crazy how much bar roll can impact your front grip. Been experimenting with rolling further forward lately and it feels good.
It’s also crazy how much bar roll can impact your front grip. Been experimenting with rolling further forward lately and it feels good.
Joined
·
4,387 Posts
?
Joined
·
725 Posts
This! I usually add extenders to my head stack to add a little bar height, however bike shops cutting the steerer tube shorter has stemied those efforts as of late.
Joined
·
5,815 Posts
Yep I'm smack bang in the middle so have generally always ridden "medium" sized bikes. I had a look at my bike model and it comes in six sizes
What blows my mind is people my height were riding the second largest size which made me wonder what really tall people rode.
I think the ratio through the six sizes was
1.67 to 1.95.
How did they come to 1.8 being the number?
Numbers like a FC:RC ratio of ~1.8 or chainstay being ~35% of the total wheelbase are basically made up. There is no "right" number or real evidence based research.
With that said, if you take an average Medium that's about what you get. For me the closer I get to that, the better my bike has felt although in XL and XXL it does get to be a pretty sizeable wheelbase and there are practical limitations/compromises one might make based on terrain.
My enduro bike is an XL GG Gnarvana which has chainstay length adjustment (440 or 450mm) and +/- 10mm reach/wheelbase adjustment at the headset. I have run every combination and the one that corners the best by far is the longer chainstay with the shorter wheelbase. I am tall and prefer the longer reach/wheelbase with the bike pointed straight but in corners - especially unsupported corners - the shorter FC feels much better.
I am curious to spend time on even longer chainstays but I ride a fair bit of tighter terrain and I do think there will be a point of diminishing returns in terms of chasing the perfect ratio versus maneuvering a 1325mm+ wheelbase. I've only ridden DH bikes that long so not much experience in tighter stuff.
I don't think you can break it down to one number, but anecdotally for me ~440mm chainstays and a ~1300mm wheelbase don't ride optimally.
With that said, if you take an average Medium that's about what you get. For me the closer I get to that, the better my bike has felt although in XL and XXL it does get to be a pretty sizeable wheelbase and there are practical limitations/compromises one might make based on terrain.
My enduro bike is an XL GG Gnarvana which has chainstay length adjustment (440 or 450mm) and +/- 10mm reach/wheelbase adjustment at the headset. I have run every combination and the one that corners the best by far is the longer chainstay with the shorter wheelbase. I am tall and prefer the longer reach/wheelbase with the bike pointed straight but in corners - especially unsupported corners - the shorter FC feels much better.
I am curious to spend time on even longer chainstays but I ride a fair bit of tighter terrain and I do think there will be a point of diminishing returns in terms of chasing the perfect ratio versus maneuvering a 1325mm+ wheelbase. I've only ridden DH bikes that long so not much experience in tighter stuff.
I don't think you can break it down to one number, but anecdotally for me ~440mm chainstays and a ~1300mm wheelbase don't ride optimally.
Joined
·
1,207 Posts
Agree - the ratio is just one metric. It doesn't take into account head angle and bar position which are going to have an impact as well. But generally speaking it gets to a point where it doesn't matter what you do, it's not a long enough chainstay.
The 441 CS on on my Meta v5 with a 1271 wheelbase actually feels really good to me, but it's got a 64 HA and full 29" wheels. Whereas my Nomad MX had a ~443 CS and 1271 wheelbase but a slacker HA and shorter reach, there's noticeably less front end grip on the Nomad in my opinion.
I wouldn't buy a size "L" bike with a sub ~440 chainstay at this point, and the slacker you go the longer the CS probably needs to be.
Also this doesn't take into account axle path. My GT Fury is a ~1300 WB and only 445 CS, but grows a bit under sag since it's a high pivot. That bike feels pretty balanced but the static ratio would say otherwise.
The 441 CS on on my Meta v5 with a 1271 wheelbase actually feels really good to me, but it's got a 64 HA and full 29" wheels. Whereas my Nomad MX had a ~443 CS and 1271 wheelbase but a slacker HA and shorter reach, there's noticeably less front end grip on the Nomad in my opinion.
I wouldn't buy a size "L" bike with a sub ~440 chainstay at this point, and the slacker you go the longer the CS probably needs to be.
Also this doesn't take into account axle path. My GT Fury is a ~1300 WB and only 445 CS, but grows a bit under sag since it's a high pivot. That bike feels pretty balanced but the static ratio would say otherwise.
Yeah, high pivots are another wrench in the gears.
A typical low pivot's rear center shortens towards the end of travel. Some a bit more, some a bit less but having looked at a fair number of charts they don't seem to vary all that much. From the Linkage Design blog:
![Image]()
The axle paths on high pivots seem to vary much more. Some stay pretty close to the same length at sag through the end of travel, some keep getting longer.
![Image]()
Definitely the number on the static geo chart is essentially meaningless for these.
A typical low pivot's rear center shortens towards the end of travel. Some a bit more, some a bit less but having looked at a fair number of charts they don't seem to vary all that much. From the Linkage Design blog:
The axle paths on high pivots seem to vary much more. Some stay pretty close to the same length at sag through the end of travel, some keep getting longer.
Definitely the number on the static geo chart is essentially meaningless for these.
Joined
·
7,189 Posts
That's because they describe two different things. FC:RC ratio tells you what the weight balance will be with 100% of the weight on the BB. It's kinda like the inherent/static weight distribution of the frame/bike.
Bar position influences weight distribution but it does so less directly. Going to a shorter stem might shift your weight rearward but if you ride with "neutral weight" aka "light hands" on the bars your weight distribution will be the same regardless of bar position (not totally realistic). Bar position changes influence how much you tend to lean or pull on the bars. It potentially alters the dynamics of weight distribution... whereas F:R ratio describes what the static/neutral weight distribution will be.
Also, it's easier to adjust bar position than F:R which is why F:R often gets talked about by itself. If I'm buying a frame I'm already looking at reach, stack, HTA, STA, etc regardless.
Joined
·
5,815 Posts
And that's the issue. There are too many variables in the bikes for it to be narrowed down to one number.
Going from my 26" Enduro to a 29" Stumpy there were so many changes that it's almost pointless for me to try and work out the differences.
The only way to test is to have multiple stays, and even then it's not straight forward as you're altering the suspension kinematics too.
221 - 240 of 246 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
