If I have two bikes with the same length toptube and one has a threadless 100mm stem, would a 100mm quill stem give the same reach?

aquateen, Stems are measured center to center whether threadless or quill.

Brad

yes, but a caveat. Most quill stems have a zero degree rise, while most threadless have some rise built in. Thus, a 100mm threadless may be slightly shorter "effectively" than an equivalent length quill type. If you get a zero rise threadless it would be identical in reach though.

My modern road bike has a 100mm stem with a 7 degree rise. I'm trying to decide what length nitto technomic deluxe for my touring bike

Perhaps this will help.

https://www.bikeforums.net/fitting-yo...l#post16586490

-17° rise for a standard road quill.

Fair enough, if measured against the headtube plane. I meant a zero rise compared to level ground.

If you want the exact same fit, you have to measure everything from the bottom bracket. Start with the saddle location, then get your bars dialed in.

If you're sure you want the bars in the same spot, mark a red dot on the Habanero chart showing the center of the bar for your current setup. You'll have to do some math to figure it out since Habanero's chart shows rise from the horizontal while on the bike whereas threadless stems are measured in degrees from the perpendicular of the steerer axis. Quill stems are measured that way or off the steerer axis itself.

Find out what your head angle is and draw some lines on this chart at that angle. Say at the 9cm point on the x axis, start a line going up and to the left at, say, 73° (if that's your HTA). Repeat for other lengths you might need.

The one that comes closest to intersecting the red dot will be the reach you'll want in the Technomic

Fun online app for stem fiddlin'

Stem Comparison Tool | yojimg.net

great.

Thanks folks. Looks like I got plenty to play with here