3

Context

To reduce bum pain after switching from cycling shorts to winter clothing (base layer + cycling waterproof trousers, with no gel pads), from an otherwise just-about-right saddle position, I moved the saddle forward (on two occasions, by 2 mm each time). I chose forward because my sit bones were losing contact much of the time with the saddle. Now one ligament (the left) in one leg (the left) hurts after riding (pain level 2-3 out of 10). I'm trying to figure out a compromise.

Question

In the figure below, the point of contact of the dashed circle and the dashed line segment is the point where the sit bones touch the saddle.

bike rough geometry

Assume you have already figured a "just-about-right" adjustment of the saddle height and the saddle forward-backward position. Assume also you did not tilt the saddle. It remained parallel to the ground.

From that initial adjustment you can assume (?) that the distance of your pelvis from the cranks (large dashed circle) is about right.

Now, every time you decide to fine tune this (already about-right) adjustment by moving the saddle forward, you also need to adjust the height of the saddle, since otherwise you'd be changing the distance to the cranks, when you have already decided that that distance is already good.

Is this true?

Conclusion

If saddle height and fore-aft are not independent adjustments, the conclusion would be that the basic adjustment sequence (saddle height; saddle fore-aft; reach) is flawed. The sequence would be either:

  • Repeat until there is no pain:
    1. Adjust height.
    2. Adjust fore-aft.
  • Adjust reach.

Or, since fore-aft itself affects reach:

  • Repeat until there is no pain:
    1. Adjust height.
    2. Adjust fore-aft.
    3. Adjust reach.
2
  • Yes, but the effect won’t be that extreme. Similarly when you raise the saddle by a few millimeters you would actually have to also move it forward a tiny bit.
    – Michael
    Nov 20 '20 at 18:22
  • If you know you’re sensitive to saddle height, go ahead and change it. For other people, the difference is well within the normal range of error.
    – MaplePanda
    Nov 20 '20 at 18:56
6

Yes, you are correct. When adjusting the fore-aft position, you do also have to adjust the height. But it is only a few mm max. Many people cannot determine their otimal saddle height with such precision.

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  • 1
    In the cold times I lower the saddle by close to 5mm because the ankle-high cycling shoes (padded) have thicker soles.
    – Carel
    Nov 20 '20 at 19:24
  • @Carel Ah! Good point. I omitted that I'm also wearing thicker socks. But wearing thicker soles or thicker socks should mean moving the saddle up, not down. What am I missing?
    – Sam
    Nov 20 '20 at 20:07
  • @Sam: you're right, of course, I lower the saddle in Spring when reverting to warm weather gear.
    – Carel
    Nov 21 '20 at 8:24
  • Agreed people will not notice a 5 mm change in saddle height. Most will not notice a 10 mm change either. Our bodies are quite adaptable, it’s not something like a gear mesh that requires super tight tolerances.
    – Rider_X
    Nov 21 '20 at 20:07

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