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Old 07-23-11, 02:14 PM   #1
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How to measure the rake of a fork

I have just received a free track fork, But i don't know what the rake is. I think it is a track fork because there is no brake hole, But i'm most likely going to drill it.

So my question is how can i measure the rake, It doesnt need to be accurate, i just need it too be with in the 5mm range like 45mm - 35mm - 30mm
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Old 07-23-11, 09:20 PM   #2
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The easiest way I know of is to mount the steerer tube in a fixture (could be a couple of "U" bolts in a 2" x 4") on top of a piece of butcher paper, and turn the fork 90 so that the dropouts are flat on the paper. Mark the paper halfway between the dropouts. This mark is the steering axis of the fork. Next, turn the fork 90 using a right angle "square" against the butcher paper surface and the rear of the fork blades near the crown to ensure it's at 90 and mark the center of the left dropout on the butcher paper. Draw a line from the steering axis and at a right angle to it, through the mark in the center of the dropout, and measure the distance from the steering axis to the center of the dropout. That is your rake or offset.

- Stan

my bikes

Science doesn't care what you believe.

Last edited by Scooper; 07-25-11 at 12:56 PM. Reason: Revised Illustration
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Old 07-25-11, 10:54 PM   #3
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Thanks Scooper! I've been wondering about that myself.
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Old 07-30-11, 03:57 AM   #4
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Nice demonstration!
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Old 07-30-11, 02:36 PM   #5
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Pretty good way to do it, I did it close to that but turned my 2x4 into a V block with a table saw. Then I got "fancy" and found a VAR fork alignment jig to help.
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Old 08-12-11, 05:57 PM   #6
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I clamp a hub in the fork and lay the fork on a flat, level surface. Using a level on the steer tube, I prop up the steer tube (books, pads of paper, steel blocks, wood blocks, whatever is around) until it measures level. I then measure the height of the bottom and top of the steer tube above the surface. The average of those two is the height above the table of the steer axis. Then I measure the diameter of the hub flange and divide by two. The difference between the hub axis and the steer tube axis is the rake.
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