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When exactly are you trying to get your weight over the back wheel? Not something I've ever found myself struggling with, can you give me an example?
Manualling, dropping, adjusting body position while jumping, going down super steep sections... It's more difficult with longer wheelbases.

Which longer reach, steep ST bikes have you tried?

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Does it matter? Physics is physics. It is more difficult to get your weight over the back wheel when your hands are farther from the rear axle. I realize that a longer wheelbase centers the rider's mass more on the bike, it makes it more difficult to weight either wheel. You can still do it, but the rider needs to exagerate their movements much more.
 

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Manualling, dropping, adjusting body position while jumping, going down super steep sections... It's more difficult with longer wheelbases.



Does it matter? Physics is physics. It is more difficult to get your weight over the back wheel when your hands are farther from the rear axle. I realize that a longer wheelbase centers the rider's mass more on the bike, it makes it more difficult to weight either wheel. You can still do it, but the rider needs to exagerate their movements much more.
Of course it matters.
The bottom line is, you have never ridden it and your experience with this kind of geometry is exactly 0%, none.
You can say what you want, until you try it, it is just an opinion not based in real life testing.

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Yup, lot's of opinions based on biases, not experience. Thank God that not all designers think like that, or we would all be on 1985 Stumpjumpers. I try to keep an open mind when new things come along. Designers don't come up with stuff like the Pole on a whim, they experiment, and find what they like. Those who don't experiment with new things never know.
 

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I don't need to try the extreme geometry to understand math. I've ridden a bunch of bikes that had all kinds of geometry, and when the front end gets longer, it is more difficult to get over the back axle.
 

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I don't need to try the extreme geometry to understand math. I've ridden a bunch of bikes that had all kinds of geometry, and when the seattube angle gets steeper and reach gets shifted forward, it is more difficult to get over the back axle. The only way to fix it is to incorporate super short chainstays, which is not always practical or beneficial, either. I'd draw you a picture comparing body positions, but you should be able to figure it out.
 

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I don't need to try the extreme geometry to understand math. I've ridden a bunch of bikes that had all kinds of geometry, and when the seattube angle gets steeper and reach gets shifted forward, it is more difficult to get over the back axle. The only way to fix it is to incorporate super short chainstays, which is not always practical or beneficial, either. I'd draw you a picture comparing body positions, but you should be able to figure it out.
How does the steep ST have any effect whatsoever on weight distribution? We are talking descending, right?

Regarding the longer front center and short CS. The opposite is desired. The longer you make the front the longer you want the CS to be. Fortunately, the obsession with short CS is slowly becoming the thing of the past.

Another good article on the topic is here:
http://www.starlingcycles.com/news/...metry-part-1-getting-it-wrong-to-get-it-right

And again, these are written by people doing some real life testing.
Fortunately their word means tons more than some armchair engineer claiming he knows it all without even trying it.
 

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Yup, lot's of opinions based on biases, not experience. Thank God that not all designers think like that, or we would all be on 1985 Stumpjumpers. I try to keep an open mind when new things come along. Designers don't come up with stuff like the Pole on a whim, they experiment, and find what they like. Those who don't experiment with new things never know.
Stop it!
We all know suspension is a gimmick, hydraulic brakes arent needed and carbon frames will crack within a week of riding!
We don't need to try it to understand how the physics work.




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Steep STA and long reach make it more difficult to get your weight over the back wheel. Count me out if that becomes the norm.
Manualling, dropping, adjusting body position while jumping, going down super steep sections... It's more difficult with longer wheelbases.

Does it matter? Physics is physics. It is more difficult to get your weight over the back wheel when your hands are farther from the rear axle. I realize that a longer wheelbase centers the rider's mass more on the bike, it makes it more difficult to weight either wheel. You can still do it, but the rider needs to exagerate their movements much more.
I don't need to try the extreme geometry to understand math. I've ridden a bunch of bikes that had all kinds of geometry, and when the seattube angle gets steeper and reach gets shifted forward, it is more difficult to get over the back axle. The only way to fix it is to incorporate super short chainstays, which is not always practical or beneficial, either. I'd draw you a picture comparing body positions, but you should be able to figure it out.
FrameGeometry.jpg

May I ask for your attention, looking at the rear center and front center on this illustration and thinking about all of this in terms of body weight balancing.

When you extend a wheelbase, yet keep the RC (chainstay length) the same, the front center gets longer. The BB effectively becomes farther away from the front axle, and a higher % of your weight resting on the BB becomes supported by the rear axle; the geo change effectively makes the bike more rearward biased. This is similar to keeping the front the same length, but shortening the RC.
- A steep STA balances out this rearward weight shift, putting your seated pedaling position back into a more balanced position that riders are more familiar with.
- A long reach balances out the steeper STA, to retain a familiar distance between the seat and bars. It's unwise to have much of the FC gain come from longer and more slacked out telescopic forks, due to how the geometry changes as it goes through its travel.

While seated, your weight would be balanced similarly to conventional bikes, with the changes balanced out like this. It's a different story when you're standing. If the longer reach was balanced by a shorter stem, then the bike will be even more rearward biased than conventional bikes while standing. On the Pole Evolink, the reach is increased to around 500mm. There'd be excessive rear weight bias, if it were not balanced out by extending the rear center.

A longer wheelbase actually makes holding a manual in its balance point a lot easier. Drops, jumps, and steeps actually can be tackled with more stability (less nervousness). They all would feel more calmer and relaxed on a longer wheelbase bike. A heavier rearward bias helps. The longer wheelbase bike doesn't better center the rider... a rider naturally finds a "balance point" on any bike, but the sweet spot for it is broader on a long wheelbase bike. This effectively gives you "more room to move", since you don't feel like you're throwing yourself off balance by moving around on the bike.

Exaggerating movements is not exactly a bad thing. I'd say becoming more active on the bike is a good thing. It's better than to be "frozen stiff" in a precise position that is maintaining your balance, to avoid being thrown off your intended course. Think of how rockets correct their course--they over-correct with a heavy movement then counter the previous movement with another strong movement once back on course. It's more beginner friendly to require broader, less precise movement. It takes a lot of repetition to develop conditioned muscles or muscle memory to pull off movements that require a high degree of sensitivity, like riding a BMX bike trials-style on a tight rope. Think about it in this sense, if you normally held your handlebars with a narrow grip by the stem clamp and used micro movements, you might think that using a wide grip on wider bar exaggerates your movements. Or maybe think about it as using a computer mouse with sensitivity turned up, so a small flick can send the cursor from one edge of your screen to the other, vs using a sensitivity setting that requires more movement to do the same--then think about how this affects various common and uncommon tasks and how one would choose based on personal needs. A dancer jumping and landing on one foot is trained to control their inertia by spreading their weight out widely.

I believe the main reason why these bikes can turn better than expected is because that the longer downtube acts as a longer lever, so the % of weight from the BB that goes to the front wheel is multiplied before it reaches the lower headset cup and puts weight through the fork to the wheel. Having weight on the front prevents the understeer that is the main weakness of extremely rearward biased vehicles. On conventional geo mtbs, this weakness tends to be compensated for by running super grippy front tires. The longer front center also makes rolling over uneven ground not upset the bike's pitch as much.

TL;DR: think of it as the ratio of weight on the rear wheel, vs the front, rather how having the bars farther forward affects your ability to get your ass hanging over/behind the rear axle.
 

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When you extend a wheelbase, yet keep the RC (chainstay length) the same, the front center gets longer. The BB effectively becomes farther away from the front axle, and a higher % of your weight resting on the BB becomes supported by the rear axle; the geo change effectively makes the bike more rearward biased.
I agree with much of what you are saying, but some of it doesn't make any sense. Take the above for example, if the rear of the bike stays the same and front gets longer then more weight is on the rear axle. Not really.

If you were to sit in the same place then the weight on the rear axle would remain exactly the same but in practice that's not the case. Stretching the front end will make the rider lean forward more and put less weight on the rear end. The opposite of what you are saying.
 

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I agree with much of what you are saying, but some of it doesn't make any sense. Take the above for example, if the rear of the bike stays the same and front gets longer then more weight is on the rear axle. Not really.

If you were to sit in the same place then the weight on the rear axle would remain exactly the same but in practice that's not the case. Stretching the front end will make the rider lean forward more and put less weight on the rear end. The opposite of what you are saying.
Yep. Lots of contradictions in his jabbering. Some is correct, like a wider range of balance and easier centering, but that doesn't make riding more fun or switchbacks and tight turns easier.

Personally, I think people that are full in on this new geometry fall into at least one of these five categories:

1). No real experience riding old geometry.
2). No real experience riding tight, twisty, technical trails.
3). No real ability to ride a bike without a geometric crutch.
4). Race and need every competitive advantage they can find.
5). Have talked themselves into the illusion that one geometry is better at everything without compromise.
 

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Yeah really makes me wonder if the long WB long bike guys mostly just ride bomber DH type tracks. I upsized to a 5010 large and regretted it in twisties and switchbacks.
 

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...5). Have talked themselves into the illusion that one geometry is better at everything without compromise.
I certainly think it's true that longer bikes are no free lunch. Most changes in bike dynamics are compromises, it's hard to get around that, and the idea that a longer wheelbase vehicle can be easier to get round a tight bend? Na, not having it.

I've watched guys on big 29er bikes on tight switchbacks. They are not having an easier time of it. The idea that it easier to move around on a bigger bike is also not true, BMX bikes are small for a reason.

I'm not saying longer bikes are rubbish, far from it, but they're not a golden bullet either. They'll be better over some kinds of terrain, worse on others.
 

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I agree with much of what you are saying, but some of it doesn't make any sense. Take the above for example, if the rear of the bike stays the same and front gets longer then more weight is on the rear axle. Not really.

If you were to sit in the same place then the weight on the rear axle would remain exactly the same but in practice that's not the case. Stretching the front end will make the rider lean forward more and put less weight on the rear end. The opposite of what you are saying.
Nope.
The distance from the saddle to bars stays the same.
What changes is the STA, reach, HTA, front centre...
The rider doesn't have to lean forward more.

The slack ST is the problem on most current bikes.
5'8.5", 31" inseam.
I wanted to go with a L SC Hightower frame. Standing it felt fine, the 450mm reach was OK. While seated it was still fine, but only with a 35mm stem and saddle all the way forward.
If the ST was properly steep, the bike would have been perfect.


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You need to read what he said more carefully.
I reacted to your claim:
"Stretching the front end will make the rider lean forward more and put less weight on the rear end. The opposite of what you are saying"
Which isn't the case...


Not sure what are you hitting at in Varaxis statement. Can you point out exactly to it?

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Not sure what are you hitting at. Can you point out exactly to his statement?
Sure.

In his first main paragraph he said that extra weight on the rear axle would result from extending the front of the bike, with no other changes. He doesn't introduce a change in STA until the next paragraph where he says; "A steep STA balances out this rearward weight shift".

So he's saying that your weight shifts backwards solely due to an extension of the front.

Making the STA steeper will indeed move your weight forward, no argument there.
 

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Sure.

In his first main paragraph he said that extra weight on the rear axle would result from extending the front of the bike, with no other changes. He doesn't introduce a change in STA until the next paragraph where he says; "A steep STA balances out this rearward weight shift".

So he's saying that your weight shifts backwards solely due to an extension of the front.

Making the STA steeper will indeed move your weight forward, no argument there.
And yet he wasn't incorrect. You are trying to devide his statement into 2 separate paragraphs, while it is obvious that he meant it as a whole...

You automatically assumed that the extension of the front center could be done solely by increasing the reach. Change in the front center can be done in numerous ways, and some will indeed shift the weight without changing how stretched out the rider would be.
- slacker HA
- increased offset
- steeper ST
- fork change
- tire size

The weight change rear vs front center is a tricky subject.
The extended front center also means more mass (talking frame) in the front and at the same time more rear weight bias of a rider, due to the unchanged rear center.

I found out I can climb strep stuff better on my AM bike with relatively steep ST and longer front center and 40mm stem than I ever could on my XC bike with old school geometry - slack ST, short WB, steep HT and 90mm stem....


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Nope.
The distance from the saddle to bars stays the same.
What changes is the STA, reach, HTA, front centre...
The rider doesn't have to lean forward more.

The slack ST is the problem on most current bikes.
5'8.5", 31" inseam.
I wanted to go with a L SC Hightower frame. Standing it felt fine, the 450mm reach was OK. While seated it was still fine, but only with a 35mm stem and saddle all the way forward.
If the ST was properly steep, the bike would have been perfect.


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jazz, didn't you say you'd choose a 5010 in large though? I figured accounting for the slightly slacker STA and the slightly shorter reach compared to the Hightower they'd practically ride the same no?
 

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And yet he wasn't incorrect. You are trying to decide his statement into 2 separate paragraphs, while it is obvious that he meant it as a whole...

You automatically assumed that the extension of the front centre could be done solely by increasing the reach. Change in the front centre can be done in numerous ways.
I'm sorry but I think it's you who are misinterpreting what he said. He said that when you "extend a wheelbase, yet keep the RC (chainstay length) the same, the front centre gets longer". No mention of the STA, in fact changing the STA does not make the wheelbase longer. He refers to this 'change', singular, at the end of the paragraph so it's pretty clear he meant that extending the front of the bike puts more weight on the rear axle. Which is what I said I didn't agree with.
 
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