Seat height on mtb vs the road bike
I've used the chart in LeMonds book for my seat height based on my actual inseam for many years, same seat height for road and mtn bikes. I was just reading (late to the book club) in Friels book that he recommends 1 to 2 cm lower on the mountain bike. Do you guys do that?
I was professionally fitted on my road and mountain bikes (using both the Specialized and Retul systems), and my MTB height is 756mm (measured from the center of the BB) vs. my road bike at 763mm.
What is the reason to run it lower? I'd think that height would be the same--it's the same rider. As for MTB, I could see running it lower on a hardtail would help help with "hover pedaling" over bumpy stuff.
Had a Retül fit, too. Same saddle height for mtb and road.
I had a retul fit for the RB. It seems to work well after I got used to it.
The MTB I did by trial and error and is different I believe for the following reasons:
-MTB saddle is different. Tundra vs Specialized toupe. Much longer saddle with different sweet spot. Not much of a crotch on saddle.
-Different shoes and pedals.
-Suspended bike, which means it sags after you sit on it thus changing your setback/seat tube angle a bit from unweighted measurement.
-Different crank lengths, 172.5 vs 175
At the end, I wound up running it about 5mm lower and forward (probably due to longer saddle). I seem to do same for my CX bike, which has 172.5 cranks and yet another saddle (Prologo). I sold the CX (ridley) and getting another one (giant) so time to redial yet another bike. Aaargh.
Last edited by Poncharelli; 08-06-2013 at 04:37 PM.
I would think the optimal saddle height for MTB would be the same as a road bike for non-technical terrain, and lower for technical terrain depending on how technical it is. I'm seriusly considering one of the on-board (adjust while riding) saddle height adjusters. Why wouldn't I set the maximum height to what I run on my road bike for those fire road climbs?
I always thought it was better for leg muscle memory (assuming there is such a thing) to have a constant seat height. I can see how it might vary from full height for smooth fast trails and cx, to a bit lower the more downhill-like the riding is. In the Mountain Bikers Training bible on page 215, the reasoning is for a lower center of gravity and allowing for foot skidding in the tricky bits.
My MTB seat height is 1.5-2cm lower than the CX bike.
Can't stand the MTB at the same height.
That was theory John Tomac operated on around 1990 when he raced a whole season on an MTB with drop bars. His reason was that he could ride using the exact same position as the road bike he was racing on in Europe at the time. He seemed to be able to handle techncial terrian just fine in the drops on a rigid bike, but I wouldn't try that. I guess we all can't ride like Tomac.
The distance between the saddle and the bottom of the pedal stoke that provides the greatest pedalling efficiency will be the same regardless of what bike you're on. On a road bike that, and to a lesser extent wind resistence are your greatest concerns.
On a mountain bike, pedalling efficiency is a concern while riding uphill and low-technical surfaces, but on technical trails and steep downhill control of the bicycle is the greatest concern.
As far as I know, 99 percent of the analysys of rider position assumes a level riding surface, but during steep climbs & descents (seldom encoutnered during road riding) the balance dynamics change so the riding position must change also. During a steep descent, the rear wheel can be much higher than the front, pushing the rider's butt up and the center of gravety forward, increasing the likelyhood of going over the bars. A lower saddle helps the rider maintain a lower center of gravity still centered over the pedals.
The other reason is better shock absorbtion. While your arms and legs can flex to absorb bumps that aren't absorbed by the suspension, your butt can't do that, so it's good to have several inches for the saddle to move up and down between your legs before it unexpectedly pushes your center of gravity up & forward where you don't want it.
The saddle moving against your leg is part of the feedback the brain gets from the bike on what's it's rolling over, and I think you're also controling the bike to a degree by pressing your leg against the saddle even when you're not seated, so I don't like it too low. The optimum saddle height for technical decents varies according to the nature of the terrain, personal preference and riding style.
Mine are near-identical. They're not bang-on, I currently have five different bikes with four different crank arm lengths, and I don't like to extend my leg too much at the bottom of the stroke.
For years, I insisted on riding with the saddle on my road bike too high. When I finally lowered it some, I got a lot more comfortable. When both my road and my mountain bike had 170 mm cranks, my saddle heights were even closer than they are now.
Aside from for purposes of being able to restore a setup if I make changes, or curiosity now and then, I don't do a lot with measurements. I rough in, and then fine-tune by riding. Since my saddles don't match each other, it would be hard to be precise with a tape measure anyway.
"Don't buy upgrades; ride up grades." -Eddy Merckx
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