Seat Position Road vs Mountain Bike

[Mudfoot]

Tons of research and help on setting up your seat position on a road bike. Does everyone set their mtb seat in the exact same position (i.e. setback from bottom bracket) as their road bike, or is it setup slightly different?

[mntlion]

I would GUESS that you would also set based on the bikes angles as well? (if you want to get THAT nerdy)

[Bunion 2020]

I find all seat position and height to be a matter of trial and error.

I measure and nerd out to get it close enough so as not to damage knees/hips/back and then dial it in doing some easy rides solo so no one gets put off with my stopping and getting out the Allen wrench and tweaking it.

[jamal]

I haven't measured, but I think my mtb saddle is a bit farther forward to keep me more centered while climbing.

From going and eyeballing it that does appear to be the case.

[XXX-er]

I pretty much run the saddle slightly nose high & slam every seat all the way forward

the road coach even noticed/said I look way better on the seat like this^^ as opposed to a flat saddle

but of course YMMV

[54-46]

Tons of research and help on setting up your seat position on a road bike. Does everyone set their mtb seat in the exact same position (i.e. setback from bottom bracket) as their road bike, or is it setup slightly different?

Different because of seat tube angle and suspension. Trial and error

Saddle level on both, though

[Mudfoot]

I believe you need to have your saddle a specific distance from the bb for your knees and leg muscles to work at maximum effectiveness, so if you move the saddle forward you need to also raise it to maintain that distance. This will make your knees happy but doesn't it screw up the leverage advantage for your pedaling, except when you are going up a very steep hill?

Bottom Line: Is the whole plum bob from knee thru the pedal axle thing inapplicable when setting up seat position on a mountain bike?

[GeezerSteve]

Bottom Line: Is the whole plum bob from knee thru the pedal axle thing inapplicable when setting up seat position on a mountain bike?

Keith Bontrager: The Myth of KOPS Note that KB's analysis is about road bikes, but his observations should apply to MTB.

IMO, the bottom line is that the answer usually requires trial and error for each individual, and most riders would easily adapt to numerous saddle positions within a range. The best ST angle and saddle position is dependent on lots of things, i.e., rider physiology, preferred muscle group loading, prioritizing pedal position efficiency vs. handling, pedaling out of saddle v. in saddle and position of rider on saddle (i.e., some riders prefer to :ride the rivet," while others like to ride on the back of the saddle).

I have experimented with a wide range of positions, building my (10 or so) frames in the past 40 years with ST angles ranging from 71* to 77*, most in between, and using zero-setback and standard setback SPs. I quickly adapted to all positions, except the very steepest (77* + zero setback) and most laid back (70* with saddle slid all the way back on a standard setback SP). Steeper seems to bring in more back of leg muscles and, conversely, laid back seems to concentrate load more on quads. Note that all my experimentation was with road bikes.

FWIW, most of the riders for whom I've built frames end up with their knee a bit behind the pedal spindle at 3 o'clock (YMMV), but there have been some outliers, including a woman who loved a 66* ST and setback post, and a triathlete for whom I built an 80* ST and used a zero setback post.

Two extremes:

Canadian professional road racer Steve Bauer -- 11 time Tour de France rider, Olympic Silver medal, multi-year Canadian road racing champ -- rode for awhile on bicycles with very slack ST angles (<60*) that put his knee way behind his pedal spindle. See pic below. He eventually changed back to a more common saddle position, although I think that decision was about handling, not pedaling.

Some triathlete bike frames have very steep STs, sometimes as steep as 80*, which puts virtually every rider's knee way ahead of the pedal spindle at 3 o'clock. Some racers started to employ very steep ST angles for time trials and pursuits, but road racing authorities banned them per rather complex and seemingly arbitrary rules that recently got even more complex and arbitrary.

[XXX-er]

[URL="https://www.sheldonbrown.com/kops.html"]K.
Some triathlete bike frames have very steep STs, sometimes as steep as 80*, which puts virtually every rider's knee way ahead of the pedal spindle at 3 o'clock. Some racers started to employ very steep ST angles for time trials and pursuits, but road racing authorities banned them per rather complex and seemingly arbitrary rules that recently got even more complex and arbitrary.
.]

wasn't that more about the funny bars the tri folk use in conjunction with the super steep seat angle ? Do they really have a maximum seat tube angle, are post that can put your seat furhter forward banned ?

[GeezerSteve]

Do they really have a maximum seat tube angle, are post that can put your seat furhter forward banned ?

Last time I checked, road racing rules do not refer to ST angle, but instead refer to saddle length, saddle tilt and position of saddle nose relative to BB plum line. The formula was recently changed, although I don't know the specifics.

Aero bar position had influence on tri bike saddle position, although as big (or maybe bigger) factor was triathletes' desire to use a bigger muscle group, specifically introducing more back o' leg muscles, with the idea of going into the running leg without overly worked quads (relative to back o' leg).

[XXX-er]

No where more than seat placement is the term YMMV more aproppo

For what reason I don't remember I wanted to love a more rear ward seat position but all the way forward just feels better

I had put the seat on my CAAD 8 flat when i bought it and it was ok but I was always just perched on it

when I tipped the nose up slightly which is the normal seat angle for me I sat in the seat looked and felt better

YMMV but I don't see how nose low could do anything but thro weight on your wrists?

[GeezerSteve]

YMMV but I don't see how nose low could do anything but thro weight on your wrists?

Pretty much for MTB. Nose down can promote more aerodynamic position for road riders (assuming they are young and flexible).

[plugboots]

FWIW, I like my two mountain bikes and my road bike to be set up as close to each other as possible, including 180 mm cranks etc.

[toast2266]

YMMV but I don't see how nose low could do anything but thro weight on your wrists?

Most of my time in the saddle is on climbs. so slightly nose down is more comfortable when the bike is pointing up. It also keeps my dick from going numb, so there's that. If I rode nose high, I'm pretty sure I'd be shooting blanks after three rides.

[XXX-er]

I live in a valley and so the mtn biking is all uphill and the road biking is on the flats, nose up is where its at for me in any case you are riding the bike and I don't know how much the angle on a hill is going to affect your junk

I think its all about the physiology i had a buddy big strong healthy atheletic dude who couldn't even ride a bike, he bought and sold 3 of them until he found this funny seat that was 2 little pads of mini-cell/ no nose

his wife complained that bicycles affected her sex life

[Mudfoot]

Some people and some seats work better with the nose up and sitting back on their "sit bones," while other like it level or nose down, the later of which switches more weight to your arms for support. Irregardless of that, I'm trying to figure out if moving the seat horizontally forward effects pedaling power. If not, then you can get away with a shorter top tube length frame. I have always set mine up like my road bike, which feels right except on steep hills when I need to slide way forward on the seat.

[jamal]

Seat angle depends on where the bars are too. I think the recent change to the uci rules allows them to be angled a bit more, which let riders get a little lower and more aero.

The saddles on my cx and mtb are like perfectly flat, but I have my road bike's bars pretty far down there and I need the saddle angled down a bit. It does put more weight on my hands, but if I had the saddle flat/angled up it would not be comfortable to sit on.

[jono]

That Bauer pic is crazy--looks like a Photoshop job!

I've never understood what you get from having the nose high if your weight is on the sit bones. I go flat to nose down on both and regardless of ST angle. For me it's just the balance between getting pushed forward versus going numb, which varies a bit depending on saddle shape and hand/elbow height. I agree with Bontrager's assessment, but while everything else can rotate, gravity always pushes down at the seat.

[detrusor]

My bikes all have the same bottom bracket spindle center to seat top distance. I use the same length cranks and have set the shoes/cleats to the same thickness etc. I have found my knees can’t take hard efforts switching between bike unless this is the same. I use a longer flatter seat in my atb so I can cram the nose up my ass on steep climbs if necessary.


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[plugboots]

Same here. I ride all 3 bikes, sometimes in the same day, so I want them to feel the same.

[GeezerSteve]

Re crank length, I rode thousands of miles on 180s when they were nearly impossible to get (Campy Record or TA) then moved up to 185s (really difficult to find) and tried 187.5s. Now I'm on 175s cuz my bad knee gets achy spinning anything longer. I don't notice much difference otherwise. There are tests (power output, VO2 and other) re crank length and the consensus seems to be that +/- 10mm doesn't make much difference in terms of objectively measured data, shorter cranks seem to correlate a bit to less fatigue and promote a more aerodynamic position (road bike). Lots of pros are using shorter cranks for time trials, and now some top 6' top triathletes are spinning 165mm or shorter.

[rod9301]

Is it the same for mountain biking?

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[joetron]

Re crank length, I rode thousands of miles on 180s when they were nearly impossible to get (Campy Record or TA) then moved up to 185s (really difficult to find) and tried 187.5s. Now I'm on 175s cuz my bad knee gets achy spinning anything longer. I don't notice much difference otherwise. There have been lots of tests (VO2 and other) re crank length and the consensus seems to be that +/- 10mm doesn't make much difference in terms of objectively measured data, shorter cranks seem to correlate a bit to less fatigue and promote a more aerodynamic position (road bike). Lots of pros are using shorter cranks for time trials, and now some top 6' top triathletes are spinning 165mm or shorter.

Yep. We’re selling 155mm cranks to triathletes like hot cakes right now(I work for Rotor). They don’t need a ton of leverage at the crank for accelerations and climbs, they just have to get up to speed and churn out the watts. The fits and positions on the most modern Tri bikes are so aggressively aero and low, the short cranks help keep the hip hinge more open and keep the knee in a better spot in relation to the 3:00 pedal position.

[kidwoo]

The fits and positions on the most modern Tri bikes are so aggressively aero and low, the short cranks help keep the hip hinge more open and keep the knee in a better spot in relation to the 3:00 pedal position.

I'm now thoroughly convinced of the following

(I work for Rotor)

You allowed to ride a recumbent in triathlons? Seems pretty comfy, aero, and efficient.

[joetron]

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