Stem Length in Relation to Rise
#1
Thread Starter
Senior Member
Joined: Aug 2007
Posts: 594
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From: Rock Island, IL
Bikes: LeMond Chambery
Stem Length in Relation to Rise
I am going to get a new stem. Currently I am running a 100mm stem with 7 degrees of rise (no, it is not flipped). I am going to get a stem that has 10 degrees of rise, but the reach on my current stem is good. Should I get a 110 mm stem to account for the loss of reach that accompanies the higher rise angle?
#2
Decrepit Member
Joined: Aug 2005
Posts: 10,488
Likes: 94
From: Santa Rosa, California
Bikes: Waterford 953 RS-22, several Paramounts
Jim,
Terminology for stems is confusing. I think when you say length, you may mean extension. Historically (threaded headsets and quill stems), length meant the vertical distance from the minimum insertion mark to the centerline of the extension. I don't believe you'll notice the difference in reach between a 7 degree and 10 degree rise. One way to see exactly how much it will affect reach is to use a compass and a protractor to plot the geometry on paper.
Maybe this will help:
Terminology for stems is confusing. I think when you say length, you may mean extension. Historically (threaded headsets and quill stems), length meant the vertical distance from the minimum insertion mark to the centerline of the extension. I don't believe you'll notice the difference in reach between a 7 degree and 10 degree rise. One way to see exactly how much it will affect reach is to use a compass and a protractor to plot the geometry on paper.
Maybe this will help:
Last edited by Scooper; 12-03-07 at 01:37 PM.
#5
Low car diet
Joined: Aug 2007
Posts: 2,407
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From: Corvallis, OR, USA
Bikes: 2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.
Someone posted this in another thread: https://www.habcycles.com/fitting.html
The angle is from the horizontal. So, add the stated stem angle to (90 - head tube angle). A typical road bike is 73*, so your 7* stem is probably about 24* from the horizontal [ie, 7 + (90 - 73) = 24], but you can round to 25*.
Your effective reach is about 90 mm. Use the chart to find the right stem to get you more height while keeping your eff. reach to about 90 mm. For example, a 110mm/17*(~35* from horizontal) stem will give you about a 2 cm increase in height with the same, 90 mm, reach.
The angle is from the horizontal. So, add the stated stem angle to (90 - head tube angle). A typical road bike is 73*, so your 7* stem is probably about 24* from the horizontal [ie, 7 + (90 - 73) = 24], but you can round to 25*.
Your effective reach is about 90 mm. Use the chart to find the right stem to get you more height while keeping your eff. reach to about 90 mm. For example, a 110mm/17*(~35* from horizontal) stem will give you about a 2 cm increase in height with the same, 90 mm, reach.
Last edited by JiveTurkey; 12-03-07 at 02:19 PM.
#6
#9
Low car diet
Joined: Aug 2007
Posts: 2,407
Likes: 4
From: Corvallis, OR, USA
Bikes: 2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.







