Proper fit on new geo

[Bewheels]

I am in the group of people that have not bought/ridden the newer geometry mt bikes but likely have one in my future. I am curious to know the how people are establishing their fit when it comes to the steep set tubes.

Most of the information that I can find is focused on how and why the new geo is is better or getting the front end sized correctly for the new geo. However I am not finding information about how you sit in relation to the bottom bracket with the new steep seat tube angles.

Historically I set-up the seat/knee/foot/pedal relationship on mt bikes pretty much the same as I would on a road bike. The seat tube angles were generally around 72.5-73 degrees and I used seat posts with setback.

The seat tube angles of the newer bikes are 74-76 degrees and are using straight seat posts.

What are people doing to get their fit worked out?
Are people finding any issues with their knees, hips, back?
Or feel as through they are not able to generate power in the same way?

I am in the North East if that matters.

[rec head]

When I set up my bike I tried to get the saddle in the same position as my other bikes. I don't remember how close I got but it works. If I had problems I would have remember more details. I don't think I would like this setup without a dropper though.

At first the new geo will feel weird and the dropper will seem stupid. Then you start learning how to ride the beast and it all comes together.

[sk_tle]

I am in the group of people that have not bought/ridden the newer geometry mt bikes but likely have one in my future. I am curious to know the how people are establishing their fit when it comes to the steep set tubes.

Most of the information that I can find is focused on how and why the new geo is is better or getting the front end sized correctly for the new geo. However I am not finding information about how you sit in relation to the bottom bracket with the new steep seat tube angles.

Historically I set-up the seat/knee/foot/pedal relationship on mt bikes pretty much the same as I would on a road bike. The seat tube angles were generally around 72.5-73 degrees and I used seat posts with setback.

The seat tube angles of the newer bikes are 74-76 degrees and are using straight seat posts.

What are people doing to get their fit worked out?
Are people finding any issues with their knees, hips, back?
Or feel as through they are not able to generate power in the same way?

I am in the North East if that matters.

It is mostly compensated by the handlebar being a bit more far away thanks to the longer top tubes.

Basically you tend to set up the back end of your bike as if it was a time trial bike except instead of rotating your whole body you will open the angle with your chest in roughly the same position as in prevous mountain bikes. In the climbs it doesn't matter, it is even an help from a power perspective and we tend to bend our elbows and bring our chest closer to the handlebars as to not have the front wheel going up in the steep stuff. In the downhills it matters even less as your ass is not on the saddle thanks to the dropper. The only place it can be annoying is on flats sections on the most extremes examples (78 to 80 degrees seat angles).

74-76 degrees bikes aren't that extreme and you shouldn't overthink it. Basically when the dropper is fully extended your saddle should be a few mm higher than with more setback/seat tube angle.

[mack_turtle]

with technical trails and the ubiquity of dropper posts, the most important way to fit a mountain bike for most riders is to consider how the bike handles when you ass is off the saddle, so start with the the BB/ grips relationship. this is not as simple as reach and stack. it takes into account where you hands are, not where the top of the headtube is. Pete Verdone has a pretty cool revision of Lee McCormack's RAD fitting philosophy. it might not provide you with the perfect fit, but it's a good baseline.

it's also been argued that steep seat tubes and dropper posts evolved together. some holdouts don't want a dropper and that's fine, but a steep seat tube without a dropper could make for an awkward bike. when all these changes on modern bikes are executed harmoniously, it can work. if you skip something, it likely not going to be ideal.

[jesseth]

As Sk_tle says, there are currently "very steep" and "steep" seat tube angles out there. This is because there is a lot of divergence in how people use mtbs now.

The "very steep" 78-80 has evolved from winch-and-plummet riding. Pedaling straight up a 10% - 20% grade gravel road, ride a 20% - 25% grade fall line trail straight back down is pushing a lot of design right now. This is the BC / PNW, rowdy east coast, steep big mountain rad riding that photographs really well. It's the 160mm - 180mm long travel bikes you see with the saddle tilted far down in front, very long reach, very steep seat angles. They are bikes that are basically never pedaled sitting down on flat or rolling terrain at all. If you're descending or riding flat ground, your dropper is all the way down and your seat relationship doesn't matter at all to your riding. Going up, the bike is always tilted, so the set up is biased towards that. This is a rare kind of riding for normal people" but it's getting tons of media attention and driving bike design on the margins. It's enduro racing geometry.

Your basic trail bike (120 - 150mm travel) is now "steep" 74-76, and it assumes you always have the seat down when descending, but the seat tube angle isn't so steep that when pedaling on flat ground you aren't being pitched forward over the bars by the seat angle (tri position per above).

I set up my various MTBs mostly trying to keep the length from center of bars to tip of seat fairly consistent in a place that lets me pedal for hours without back pain, with stems that are all now in the 40 mm - 50mm range for their handling benefits. Bars 760 - 780mm range for 5-11 height. I don't pay attention at all to knee over pedal spindle. My basic method is set the stem and bar width for the terrain and style of riding, then move seat forward and back until the sitting reach feels good.

Bars tilted at an angle so wrists are straight and not bent backwards, usually slightly rotated upwards from horizontal for me.

[Bewheels]

Good info.

To add more background
- the use will be all human powered (no lifts/truck ride to the top of a hill) and no hucking/ramps.
- travel will likely be in the 100-120 range

[thollandpe]

I compensate for this by simply ignoring the new geo. Setback post (even a dropper, I use the Special__ed Command Post).

Proper is proper. One of the best, fastest, and most elegant mountain bike riders I ever had the privilege of racing with, Scooter from Merlin, was complaining about back pain after "modernizing" his position at the urging of a local shop. I told him that changing how he sat on and pedaled the bike was like adding certain anatomically-correct features to the Mona Lisa. With a Sharpie.

No need to unlearn what you have learned, set up the bike the way you'd set up the bike. Unless you also plan to use flat pedals, because if you move your feet forward your ass should follow. If you end up with a shorter stem and wider bars, that's probably good considering what we used to wrangle with.

[sailor]

As Sk_tle says, there are currently "very steep" and "steep" seat tube angles out there. This is because there is a lot of divergence in how people use mtbs now.

The "very steep" 78-80 has evolved from winch-and-plummet riding. Pedaling straight up a 10% - 20% grade gravel road, ride a 20% - 25% grade fall line trail straight back down is pushing a lot of design right now. This is the BC / PNW, rowdy east coast, steep big mountain rad riding that photographs really well. It's the 160mm - 180mm long travel bikes you see with the saddle tilted far down in front, very long reach, very steep seat angles. They are bikes that are basically never pedaled sitting down on flat or rolling terrain at all. If you're descending or riding flat ground, your dropper is all the way down and your seat relationship doesn't matter at all to your riding. Going up, the bike is always tilted, so the set up is biased towards that. This is a rare kind of riding for normal people" but it's getting tons of media attention and driving bike design on the margins. It's enduro racing geometry.

Your basic trail bike (120 - 150mm travel) is now "steep" 74-76, and it assumes you always have the seat down when descending, but the seat tube angle isn't so steep that when pedaling on flat ground you aren't being pitched forward over the bars by the seat angle (tri position per above).

I set up my various MTBs mostly trying to keep the length from center of bars to tip of seat fairly consistent in a place that lets me pedal for hours without back pain, with stems that are all now in the 40 mm - 50mm range for their handling benefits. Bars 760 - 780mm range for 5-11 height. I don't pay attention at all to knee over pedal spindle. My basic method is set the stem and bar width for the terrain and style of riding, then move seat forward and back until the sitting reach feels good.

Bars tilted at an angle so wrists are straight and not bent backwards, usually slightly rotated upwards from horizontal for me.

Please enlighten me on where I can find rowdy riding in new england, I have been quite disappointed in Eastern Mass, flat rocks and roots are not very interesting.

To the OP, for XC riding I would say 74ish with a straight post is a good spot, 76+ will feel too far forward on flat or rolling ground. Don't size down as you will be cramped, and you want to run a shortish stem and don't expect it to ride like a road bike you need to drive the front wheel.
My trail hardtail has a slacker seat angle and longer stem then my enduroish FS bike and feels much better hammering the flats.

[jscottyk]

Please enlighten me on where I can find rowdy riding in new england, I have been quite disappointed in Eastern Mass, flat rocks and roots are not very interesting.

I'm far far from being a New Englander, but can say the four days I rode at Highland Mountain definitely included some rowdy terrain.

As for bike fit on these contemporary MTB geo, here's another vote for Lee's RAD. I'm curious to check out PVD's take on it.

[boots2000]

I have experienced issues on newer geo bikes- Also experienced issues after switching to a dropper on my hardtail.
I can ride it for an hour- But 3,4, 5 hour rides become uncomfortable on a bike where I lose 2-3cm of saddle setback.

[Bewheels]

I have experienced issues on newer geo bikes- Also experienced issues after switching to a dropper on my hardtail.
I can ride it for an hour- But 3,4, 5 hour rides become uncomfortable on a bike where I lose 2-3cm of saddle setback.

I assume the issues switching to a dropper were related the change in setback/butt position and not the dropper functionality. Is that correct?

[boots2000]

Correct- Dropper work great and I love the functionality of a dropper. But the change of setback puts me in a less than ideal position.
This is even more pronounced on a modern full suspension bike with an even steeper seat angle to start.

I assume the issues switching to a dropper were related the change in setback/butt position and not the dropper functionality. Is that correct?

[jesseth]

Please enlighten me on where I can find rowdy riding in new england, I have been quite disappointed in Eastern Mass, flat rocks and roots are not very interesting.

Know the feeling. I’ve acclimated to coastal tech, but it’s an acquired taste mostly because i don’t love driving a ton.

Rowdy zones: North Conway is ground zero, esp Hurricane / Cranmore zone. Burke upper mountain. Sunday River closed bike park. Charlemont trails across from Thunder Mountain, Belnap Mtns in central NH. Bolton Valley VT. Diamond Hill in RI is surprisingly fun for 300’ of elevation. Think Jiminy Peak has some scary stuff also. It’s out there.

There’s a start.

[rabo]

Is doing long climbs on a steep <75* seat angle really more difficult?
On the flats I can see the problem , but climbs consistent over ~ 12 %?

[darkmother]

Is doing long climbs on a steep <75* seat angle really more difficult?
On the flats I can see the problem , but climbs consistent over ~ 12 %?

I think it might have to do with the *really* long front center of these bikes. In order to weight the front wheel, you have to scoot your ass forward.

[darkmother]

Also, it may be that the longer travel FS bikes 'settle in' to a climbing ST angle that is not as steep as what is published

[darkmother]

Also, it may be that the longer travel FS bikes 'settle in' to a climbing ST angle that is not as steep as what is published

[rabo]

Sorry.
I meant > 75 degrees not <.
At 6"5 on a 73 seat angle my problem is keeping the weight on the front wheel.
Especially if I'm in the 28/36 gear the front wheel keeps coming up when it gets real steep.

[sk_tle]

Also, it may be that the longer travel FS bikes 'settle in' to a climbing ST angle that is not as steep as what is published

we obviously have to take sag into account when comparing hardtail and fs.

[suspectdevice]

For the majority of Western Ma/Capital Region riding something in the XC race realm will be the only fun solution. You’ve been riding long enough that you will barely, barely, barely need to use a dropper post on something XC-ish. If you buy from the xc race end of the catalog you might find you don’t need to use the dropper at all.

Seat angles steeper than 74 or 75 for people who don’t need/use droppers and ride rolling old school trail will suck for the constant seated/standing transitions that make oldschool woods riding fun.

XCO-style bike setup is kinda similar as it’s always been, with the switch to bars wider than 710mm and “long 70mm stems” as the only things that will change how you setup contact points.
I’ve always run my seat farther forward on XC and CX bikes than on most of my road bikes. That used to be coupled with longer cranks than my road setup, but these days If you end up with a significantly steeper seatube than you are used to, just make sure you lop 5mm or so off your historical crank length, let the crazy low gears do their thing, and spin smaller, more traction filled(partly because you are more centered on the bike)circles than you are used to.