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Rear travel measurement method?

WheelieMan

Monkey
Feb 6, 2003
937
0
kol-uh-RAD-oh
I have been designing (not building unfortunately) my own bikes for a while now and have been stumped by something recentley. I have always thought that the rear travel measurement is the total displacement of the axle. In other words, the straight line distance from the rest position to the bottom out position. However, I have also heard that rear travel is measured by the total "vertical" distance that the axle travels. This might seem kinda trivial, but with high-pivot bikes, I have found up to a 7mm difference between the two measurements. Is one method more correct than the other in the mountain biking industry?
 

ohio

The Fresno Kid
Nov 26, 2001
6,649
23
SF, CA
Different companies measure it differently. Rarely is an 8.5" travel bike actually exactly 8.5". For shock tuning the instantaneous leverage is what's most important, and if you back out of that for a single pivot, you get the length of the path itself rather than the chord length. For linkage bikes, it's a moot point, because that number doesn't really effect anything else. For designing purposes, that is.

For comparing bike to bike, straight line distance between axle at top-out and bottom out should be the standard measurement, IMO.
 

BMXman

I wish I was Canadian
Sep 8, 2001
13,827
0
Victoria, BC
I don't think the distance of an axle path that runs parallel to the ground should be counted...I mean frames that have an S, J, or L curve...but that's just me...D
 

verticult

Chimp
Jan 7, 2005
53
0
I use "vertical wheel travel" . distance from lowest position to highest position measured in a vertical line. Sinister Bikes