stem height, fore-aft seat math

[54ny77]

raising stem a tad (about a half cm), wondering how much of an impact that'll have on the fore-aft adjustment on seat tube. it's a caad9 frame, seat tube is 73.5degrees, heat tube 73 degrees, top tube is 54.5cm. is that splitting hairs? will prob. know after riding if i'll be able to feel it, but am wondering what the math is on it, e.g., if it's a 1mm up stem = 0.1mm seat back kind of thing, or ballpark close.

[Cicli]

This helps.

http://yojimg.net/bike/web_tools/stem.php

[BdaGhisallo]

raising stem a tad (about a half cm), wondering how much of an impact that'll have on the fore-aft adjustment on seat tube. it's a caad9 frame, seat tube is 73.5degrees, heat tube 73 degrees, top tube is 54.5cm. is that splitting hairs? will prob. know after riding if i'll be able to feel it, but am wondering what the math is on it, e.g., if it's a 1mm up stem = 0.1mm seat back kind of thing, or ballpark close.

Why would your saddle position have to be modified when you move the stem? Wouldn't you be moving the stem to improve your fit or comfort at the front end?

[54ny77]

thanks that is exactly what i was looking for, i forgot about that page but bookmarked it for the future if needed. :beer:



This helps.

http://yojimg.net/bike/web_tools/stem.php

[charliedid]

raising stem a tad (about a half cm), wondering how much of an impact that'll have on the fore-aft adjustment on seat tube. it's a caad9 frame, seat tube is 73.5degrees, heat tube 73 degrees, top tube is 54.5cm. is that splitting hairs? will prob. know after riding if i'll be able to feel it, but am wondering what the math is on it, e.g., if it's a 1mm up stem = 0.1mm seat back kind of thing, or ballpark close.

I don't believe math counts in this small of a change. Not to say that raising the bars can't or doesn't effect the angle of your hips because it can and sometimes does.

Let your body determine what's best with these micro adjustments.

[54ny77]

fully agree, and yep the net effect based on that stem calculator is splitting hairs. that webpage is super super helpful. body will tell me if i need to tinker w/fore-aft. thanks again tihespa for the link.

I don't believe math counts in this small of a change. Not to say that raising the bars can't or doesn't effect the angle of your hips because it can and sometimes does.

Let your body determine what's best with these micro adjustments.

[charliedid]

That is indeed a very useful tool that I also use.

[Gummee]

raising stem a tad (about a half cm), wondering how much of an impact that'll have on the fore-aft adjustment on seat tube. it's a caad9 frame, seat tube is 73.5degrees, heat tube 73 degrees, top tube is 54.5cm. is that splitting hairs? will prob. know after riding if i'll be able to feel it, but am wondering what the math is on it, e.g., if it's a 1mm up stem = 0.1mm seat back kind of thing, or ballpark close.

I'm curious why raising or lowering a stem has anything to do with fore and aft at the saddle. If you're legs are in the right spot in one position, they should still be in the same spot in another position. Nothing's changing but your torso angle from the hips

...or am I missing something?

M

[Ronsonic]

I'm curious why raising or lowering a stem has anything to do with fore and aft at the saddle. If you're legs are in the right spot in one position, they should still be in the same spot in another position. Nothing's changing but your torso angle from the hips

...or am I missing something?

M

This ^

I can see a change in bar position altering the angle of the saddle, but not so much fore-aft. That is determined by hip-knee-pedal positioning.

And, just carry a pocket tool and if changing one thing requires a change to something else, then do it.

[fuzzalow]

This talk about the splitting of hairs over stem measurements isn't an outgrowth (!) of anything from that whole ridiculous "manscape" thread, is it?

[Cicli]

This talk about the splitting of hairs over stem measurements isn't an outgrowth (!) of anything from that whole ridiculous "manscape" thread, is it?

Mine measures at 10" if I hold the ruler backwards.

[54ny77]

By the way I didn't mean fore-aft seat adjustment as in adjusting the saddle position I meant reach, just forgot what to call it. Womdered if I'd need a longer stem to stay in the same spot, as it were. All's good. Thx.

Fuzz that thread was waaaaaaay too much info!

[Gummee]

When figuring out reach on a stem when changing angles or height, I'll use the tool listed above too.

If you're changing bars to ones with different reach, it comes in handy again. Get the reach the same via raising/lowering the stem and adding/subtracting angle.

For example: I'm thinking about trying some Aeronovas. They say the reach is 104mm. I'm coming from Ergonovas, so I'm going to have major stem-length changes.

M

[Joxster]

The only time my saddle height changed was during a stage race, your saddle went down as your hamstrings shortened and I stretched every night.