Hi all
My new road bike has the stem pointing up, and is high for me. Before I flip it, could someone tell me if I've got my maths right working out the change it will make:
Stem 115mm long, 8 degree rise.
Flipping it, difference in height will be 2x (115xsin(8degrees))= 32mm, give or take a little
Long time since I did any maths, anyone agree/disagree?
Cheers!
Quick (non calculator method) check would be
1deg x 60mm = 1mm
8deg x 120mm = 16mm
2x16mm is 32mm, so yes you're correct.
you have ignored the head angle.
yep 32.010mm
You need to know the head angle.
Assuming head angle is less than 90 degrees, presumably the total change in height of bars perpendicular to the floor will be slightly less than the 32 mm I worked out, then?
You need to know the head angle.
OK clever clogs, 30.5mm (its a road bike therefore 73deg is pretty standard)
Otherwise just call it the small angle aproximation (sin90=1 therefore sin73~1)
If you wanted to be really picky then you could also say that his bars will be 9mm further foreward as well so he might need a 10mm shorter stem.
32sin(HA). assuming 73° then it's 30.6mm
EDIT: too slow
Thanks all, great stuff!
http://www.brightspoke.com/t/bike-stem-calculator.html
very handy
or more visual
http://yojimg.net/bike/web_tools/stem.php
Durr... Just flip the stem and see what it's like.
Saves all that fannying about...