Math question about stem length and angle
#1
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From: burlington, mass
Bikes: Jamis Quest Elite - 2014
Math question about stem length and angle
Was fitted recently at LBS, among other adjustments, moved saddle forward as I was pretty far back behind the center of the cranks. All the adjustments feel better to me after 2 rides, but I now feel a bit compressed as I am now closer to the bars, especially when on the hoods.
I am thinking that I may need to get a longer stem or one with more of an angle. I am currently using a 90mm 84 degree stem. Obviously going to a 100mm gives me 10 more millimeters of reach.
Does anyone know what the effect of going from a 90mm 84 degree stem to a 90mm 80 degree stem would add to reach?
Thanks.
I am thinking that I may need to get a longer stem or one with more of an angle. I am currently using a 90mm 84 degree stem. Obviously going to a 100mm gives me 10 more millimeters of reach.
Does anyone know what the effect of going from a 90mm 84 degree stem to a 90mm 80 degree stem would add to reach?
Thanks.
#2
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From: Boulder, CO
#3
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From: Loveland, CO
Bikes: Cervelo Rouvida x 2
Still about 10mm. The angle effect of 4 degrees will have a minor effect on length, and a bigger effect on the bar height. The 80 degree stem drops the bars about 5mm.
To figure all of this, assume a 73 degree head tube angle. The stem angle is 84-73 = 11 (relative to the ground).
The horizontal length of the stem would be cos11 x 90 = 88.3. The height would be sin11 x 90 = 17.2. With an 80 degrees stem it's cos7 x 100 = 99.3 and sin7 x 100 = 12.2. That makes the length difference 11mm and the height change 5mm.
To figure all of this, assume a 73 degree head tube angle. The stem angle is 84-73 = 11 (relative to the ground).
The horizontal length of the stem would be cos11 x 90 = 88.3. The height would be sin11 x 90 = 17.2. With an 80 degrees stem it's cos7 x 100 = 99.3 and sin7 x 100 = 12.2. That makes the length difference 11mm and the height change 5mm.
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#6
Wow. Fantastic stem calculators on those links above. Thank you. I had no idea something like this existed. Sure does make figuring out which replacement length/angle stem to get much easier.
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