Stack Height of Stems

[93legendti]

Anyone notice how widely the stack height of various stems can vary? The height of these 31.8 stems, in 11cm length, are:

FSA 150: 34mm
Easton EA70: 40mm
Oval Concepts: 44mm
Ritchey Pro: 39mm

I noticed this after using the FSA (at the time the only 31.8 stem in 11cm I had) to fit for my new Ottrott and using an Oval Concepts stem for the Ottrott build--not to mention that the FSA 150 is really 11.5cm long!

[Louis]

Yes, to the point where if someone has cut down a steerer tube to match a low SH stem and not used any spacers below that one is forced to go out and find a similar stem, without knowing what in the world the previous owner used.

Just today I was wondering how much below the top of the stem clamp I was willing to risk having the end of the steerer tube...

[93legendti]

It's crazy. I thought my Ottrott was too small because compared to my Fierte, which was the basis for my fit on the Ottrott, I felt on the verge of being scrunched up. The Fierte was a touch too long and too tall, so my Ottrott was designed with .5cm less tt and, iirc, .6cm less s.o. at the HT. I finally measured the stem of the Fierte and a light bulb went off.

Fierte: 53.5cm TT, 11.5cm stem, 34mm stack height. Result: a bit too long
Ottrott: 53cm TT, 11cm stem, 44mm stack height. Result: a smidge too small--I am switching the Oval stem on the Ottrott for an Easton and it should be much better.

[quattro]

For clarification, when you say stack height of a stem do you mean the purchase of the stem? Thanks

[93legendti]

For clarification, when you say stack height of a stem do you mean the purchase of the stem? Thanks

No...I think.

[FierteTi52]

For clarification, when you say stack height of a stem do you mean the purchase of the stem? Thanks

Adam is refering to the "collar height" of the stem. This is how much of the fork's steerer tube is take up by the stem clamping area.
Jeff

[93legendti]

Adam is refering to the "collar height" of the stem. This is how much of the fork's steerer tube is take up by the stem clamping area.
Jeff

Yes, thanks Jeff. I thought I saw this measurement referred to as "stack height".

I have my Oval and Ritchey stems side by side--the difference in height is remarkable.

[benb]

Maybe it's a mountain only thing but I have a Titec stem that has a 50mm stack height.

I just switched it and the new one was 40mm.. had to go buy a spacer.

I would much rather rider around with an extra spacer here or there then risk not having enough steer tube if something needs to be changed.

[quattro]

I think we are talking about the same thing. The folks at the shop where I was fit and bought my frame call this the purchase of the stem. Has anyone else heard of "stack height" referred to as purchase?

[93legendti]

I haven't.

[Ken Robb]

the variation negates the supposed advantage of threadless stem/forks allowing easy swaps of stems.

[dave thompson]

I think we are talking about the same thing. The folks at the shop where I was fit and bought my frame call this the purchase of the stem. Has anyone else heard of "stack height" referred to as purchase?
I've heard it used in England, meaning 'grip'. I suppose one could extend the meaning to 'gripping area'