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Where is a good starting position for my saddle fore/aft? I have a very long tib/fib compared to my femur length. My inseam is 85.5cm long, my saddle height is currently 76.8cm from the bottom bracket, and when I checked my saddle position fore/aft today by dropping a plumb from my knee over the pedal spindle, my knee was 21mm behind the pedal spindle. It seems pretty far back. I know that KOPS is pretty much discounted on the board: what is a typical range for a standard road-race setup?

I am racing Cat3 and, according to others, I am having trouble spinning. I also feel a bit jerky: I can spin one-legged, but definitely don't feel my hamstring working much. I really want to increase my efficiency on the flats with a more efficient spin: I may be pushing too much with my quads. The only trouble is that I need a new seatpost: my post with 20mm of setback has my SLR Gel saddle pushed forward as far as it will go. Any ideas?
 

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Everyone has their own preference, so if you want permission to move your seat farther forward, you've got it. Record your position beforehand; you can always move it back to the way it was before. You may want to try a non-setback seatpost like a Thomson if you're out of room on the saddle rails. Also, you may need to raise your seat a touch after moving it forward. Good luck!

Cheers,
Ari
 

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+1/-3

The generally accepted range for position is KOPS +1/-3 cm. People who want to spin more and/or have shorter femurs tend to be more forward, and masher/longer femur folks tend to be farther back. Don't forget that when you move the saddle forward you have to raise it as well to keep the same pedal-saddle distance. It sounds like you should move forward a bit.
 

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I know that KOPS is pretty much discounted on the board:
Strange – I’ve always felt that KOPS on this board is the untouchable baseline of bike-fitting. :)

KOPS may actually be a good baseline, but some believe it’s very difficult to check it when sitting on a non-moving bike and not applying any power. Just lowering or raising your heel will move your KOPS plumb line 2 cm fore or aft. Most riders do not know if they pedal heels up, heels down or in a neutral position during a hard effort. So to many coaches and riders, a KOPS adjustment derived from a stationary rider exerting no power is hit-or-miss at best, completely useless at worst.

Some years ago, an attempt was made to collect fit dimensions from successful riders and come up with some fit suggestions based on these numbers. Hinault in one of his books gives ranges of saddle setbacks (nose-from-BB center) for "a normally proportioned body" based on inseam alone. Obviously, that approach ignores many things of both bike and rider. Perhaps because of that, this approach has pretty much been discounted, or perhaps just forgotten. But I still think the numbers may be of some value for an initial setup. From Hinault's Morphology, Position & Frame Design:

75-78 cm inseam = 4-6 cm setback
79-82 cm inseam = 5-7 cm setback
83-86 cm inseam = 6-8 cm setback
87-90 cm inseam = 7-9 cm setback
 

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how do you account for different lengths of saddles?

wim said:
Strange – I’ve always felt that KOPS on this board is the untouchable baseline of bike-fitting. :)

KOPS may actually be a good baseline, but some believe it’s very difficult to check it when sitting on a non-moving bike and not applying any power. Just lowering or raising your heel will move your KOPS plumb line 2 cm fore or aft. Most riders do not know if they pedal heels up, heels down or in a neutral position during a hard effort. So to many coaches and riders, a KOPS adjustment derived from a stationary rider exerting no power is hit-or-miss at best, completely useless at worst.

Some years ago, an attempt was made to collect fit dimensions from successful riders and come up with some fit suggestions based on these numbers. Hinault in one of his books gives ranges of saddle setbacks (nose-from-BB center) for "a normally proportioned body" based on inseam alone. Obviously, that approach ignores many things of both bike and rider. Perhaps because of that, this approach has pretty much been discounted, or perhaps just forgotten. But I still think the numbers may be of some value for an initial setup. From Hinault's Morphology, Position & Frame Design:

75-78 cm inseam = 4-6 cm setback
79-82 cm inseam = 5-7 cm setback
83-86 cm inseam = 6-8 cm setback
87-90 cm inseam = 7-9 cm setback
Formular: it is 100% individual.

I have Arione which is 30cm and Aliante which is 26.5cm long. And my SI Flite was different length and shape again. All saddles have different shapes and lengths meaning you tend to sit differently on them. If there is a formula for saddle fore/aft I would say there would be so many dependencies as to make it 100% personal fit and nothing but personal fit. The best way re saddle position that I know of was described by Steve Hogg on www.cyclingnews.com. Do a search if you like. Basically you need to be able to teeter on the brink of falling forward, if you let your hands go when in the drops. If you fall forward almost uncontrollably or have to arch the back to hang on then you are too far forward, if you pass the test relatively easy then you are too far back. The truth is in the middle where you can hang on with little (back) effort for a second or so whilst pedalling under load in ~53/15 so you use your feet as platform a little bit to stay upright. Most riders tend to be -1cm to -3cm, behind KOPS from what I have read, statistically. In my example, -2cm approx.
 

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Back in the days.

how do you account for different lengths of saddles?
As I said in my post, the Hinault numbers ignore many factors - including that of saddle length. However, Hinault made these suggestions when almost all saddles were pretty much the same length. Also, Hinault gives a range, not an absolute number. He knew that KOPS is a starting point, no more.

I like Steve Hogg's approach, in particular his insistence on dynamic fit. He understands how everything changes once the bike is rolling out on the road and the rider is cranking out power.
 
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