Originally Posted by
kingsqueak
So my saddle rails position was set up for knee over pedal in a shop. It all feels good when I'm properly back on the saddle, the width is good and pedalling feels smooth.
During the ride I keep finding myself slipping forward, which leads to the obvious resulting discomfort. I'm fine when I slide myself back onto the flats.
I think the saddle fore and aft is right, it's level and the height feels right.
My suspicion is that my stem is too long and that as I reach to get on the hoods, I wind up creeping forward on the saddle as I pedal.
Does this sound...sound?
Trying to sort out what might be causing me to slip forward on the saddle over time.
You can tell from the pic that the seat is a bit forward on the rails and I don't think due to pedal position I should move it any farther. If I measured the stem right, I measured center of the steerer to center of the bars at 100mm, I think I can drop to an 80 or so and that might "push" me back onto the saddle properly.
I have to say, this is the first bike I've ever owned where a bit too big was the issue.
I like the bike!
I have some ideas about slipping, tilt, and reach, so let me try to share them. I have fixed this issue on one of my bikes, and this is how I did it. I wish I still had it.
Slipping forward can be caused by saddle tilt, which your picture clearly shows, or a long reach. Some saddle setup approaches say to assess slipping in a seated upright position, pedaling on a trainer. If you aren't staying in place without your arms trying to reach the bars, the saddle is either not in place or it is tilted. First step is to pedal while sitting upright and see if you tend to slide forward. If you are exerting force to hold yourself on the sweet spot, level the saddle or gradually tilt up until the effort disappears. If it is tilted up too much you may find yourself tending to slide rearward.
Once this is resolved (sit bones naturally remain in the sweet spot), fold forward from the hips, not the lower back, and see if the reach to the bars feels natural or at least workable. It could still be that your bars are too far away, too low, too wide, et cetera.
As you pedal with your hands on the bars, you should find less hand pressure since you do not need to press yourself backwards to remain on the saddle. At this point it might be valuable to experiment with bar height, if you have a quill stem or it is similarly easy. I found that pressure on my hands (downward pressure) was relieved by dropping the bar (quill stem) by about 1 cm. It felt more natural for my hands to be in that position.