How do you figure out where you're sitting on a saddle?

[Louis]

Sounds like a silly question, but here's the story:

Earlier this week I swapped out my Regal for a Rolls. Since they both have the same overall shape (when viewed from the top) and the same length, I put the Rolls the same distance from the bars as what I had been using for the Regal.

However, because the Regal has rivets in back and the Rolls has padding all the way to the end I'm wondering if I'll tend to sit farther back on the Rolls. I always figured that your position on the saddle is determined by the width of the "side of the wedge" portion of the saddle, since that's what determines where your legs go. The real issue for me is where your sit bones end up and I have a hard time figuring that out.

Here's why I even care: For years I've had all sorts of knee problems, but in the last four months or so after some tweeks of saddle height, things have been going well, with few issues. I swap out the saddle and on both of my rides with the Rolls I start to get that bad old feeling in my left knee. :crap: It might just be a coincidence. I'm 100% sure I have the Rolls within +/- 1mm of the Regal for height. I'm just not sure about my fore-aft position.

As I see it, I have two options: 1) Move the Rolls about 5mm forward and see what happens, or 2) Go back to the Regal. I'm leaning to #2 because it's not obvious that the Rolls is more comfortable. Haven't really been on a long enough ride to know for sure.

Any thoughts?

TIA
Louis

[CNY rider]

Put Regal back on.
Measure relationship of knee to pedal spindle.
Remove Regal, put Rolls on and position using the knee/pedal spindle as guidance.

[cmg]

put the regal back on and measure the fore/aft from the BB. drop a string from the front of the nose and see where it falls horizontally to the BB. Set the rolls the same distance.

[Louis]

Yeah, I guess I'll have to do it the hard way. (Can't do what you guys suggest alone - you have to use a helper / fitter.)

Either way, I think I'll put the Regal back on tonight. I have no centuries planned soon, so I can live with that.

Thanks guys.

[RPS]

I'm 100% sure I have the Rolls within +/- 1mm of the Regal for height.
Louis, have you considered that you may not sit at the same height after applying weight to both saddles?

1 MM is indeed a lot of accuracy, but do both saddles flex/compress within 1 MM of each other due to your weight? I normally start the same way (set them at the same height as you did) but then tweak from there to get the same amount of flex in my left knee. Ultimately I focus more on that than anything else.

[Ti-Boy]

I measure from the sweet spot of the saddle to the bars. That is usually defined as the center of the widest part of the saddle where the sit bones fall. This way if a new saddle dimension changes, the relationship should remain the same.

[Acotts]

Ride without shorts for 30 miles. Look for visual clues on saddle after. Measure it with a ruler and compass. No repeat with new saddle.

Then wash bike.

[Louis]

Louis, have you considered that you may not sit at the same height after applying weight to both saddles?

I thought of that and added a bit to the Rolls height to attempt to compensate for the thicker padding. Not sure how the final "body position" compares, but I can't measure myself so I that was the best I could do.

Seems a bit like overkill to have to use the LBS / fitter for just a saddle swap, but I guess that's the only way to know for sure.

[Louis]

Ride without shorts for 30 miles. Look for visual clues on saddle after.

Gee, why didn't I think of that? :butt:

[gman]

Get a pair of vernier (sp?) calipers, open them up and place them on the Regal anywhere along the length toward the "spread" of the saddle. Measure from the back of the bar to the caliper.

Don't change the caliper width as you remove it from the saddle!

Put the Rolls on and place the caliper in whatever place in which the opening just touches the sides of saddle. Measure the same distance as before. Adjust as needed.

The "sweet spot" should be pretty darn close +/- 1mm if you have a steady hand with the caliper.

Hope that makes sense. I have had a few beers and it's quite possible that it isn't going from brain to fingers well.

[Louis]

Hope that makes sense.

Yes, it does make sense, but I think that's essentially the same thing as assuming that because the overall shape of the side of each saddle is similar (when viewed from above) then placing each one the same distance from the bars will work. Net result should be the same location. (Which is what I did.)

I've decided to put the Regal back on and will do that before my ride on Saturday.

[WadePatton]

easy, i look at the divits in the leather.

[allegretto]

Yes, it does make sense, but I think that's essentially the same thing as assuming that because the overall shape of the side of each saddle is similar (when viewed from above) then placing each one the same distance from the bars will work. Net result should be the same location. (Which is what I did.)

I've decided to put the Regal back on and will do that before my ride on Saturday.

yes!

trust your derriere. it will not let you down...