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A relatively straightforward way to measure fork rake?

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A relatively straightforward way to measure fork rake?

Old 01-10-18, 09:57 PM
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ryoanji
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A relatively straightforward way to measure fork rake?

I am probably very bad with search because I am quite sure this issue has been discussed extensively previously here, but I was wondering if someone can suggest a relatively straightforward way to measure fork rake? Relatively straightforward meaning can be done at home with decent collection of bicycle tools. I have a custom made road fork that I would love to finding the rake on.

Many thanks in advance!
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Old 01-11-18, 12:17 AM
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unterhausen
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put the steerer on a book that lets it lay flat. Measure to the dropouts, average the measurements, subtract the thickness of the book.
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Old 01-11-18, 01:27 AM
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If it is in a frame you can measure to the center of a chainring bolt, raise the bars and turn the fork backwards and measure again. The difference is twice the rake.
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Old 01-11-18, 08:45 AM
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Originally Posted by unterhausen
put the steerer on a book that lets it lay flat. Measure to the dropouts, average the measurements, subtract the thickness of the book.

And subtract the steerer's radius. Or use a block that lets the fork be measured rake up and rake down and find half the difference.


Not yet mentioned is the axle to crown and the brake hole to crown measurements. Andy
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Old 01-11-18, 03:29 PM
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unterhausen
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or use Kontact's method with the book

How do you measure a/c? I just use my fork fixture. Although the scale is messed up for tapered steerers.
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Old 01-11-18, 03:50 PM
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Originally Posted by unterhausen
or use Kontact's method with the book

How do you measure a/c? I just use my fork fixture. Although the scale is messed up for tapered steerers.
I would measure a/c directly to the dropout from the side of the crown. Then use that as the hypotenuse along with the rake to calculate the actual a/c as the other leg of the 90° triangle.

One advantage of this method is that you will get very close to the same answer regardless of whether you have the exact rake or not. Even if you get rake wrong by 10mm, it will only change the calculated a/c by 1mm.


This is the reason that measuring to a random point on the bottom of the crank also produces reasonably accurate results for the rake measure - the angles are too shallow to matter that much.
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Old 01-11-18, 04:28 PM
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Here's how I do it.

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Old 01-14-18, 02:03 PM
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Thank you for all suggestions, I just tried measuring and I am coming up with 56-57mm rake for a road fork (372 a/c, and it has CX crown). Interesting, it almost looks like it was designed for some kind of rando bike with fat 650B tires... Hmm.
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Old 01-15-18, 02:11 PM
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Fat 650B and 700c-35 will be nearly the same.. so a lot of bikes get converted.. 27" wheel , adding longer reach braked..
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