How to Determine Front Ends Length and Rake

If you are trying to determine the length of a custom front end for your bike you should take many things in consideration. The look that you are trying to achieve, the height of the wheels and tires that you are going to use, rake and height of the frame as well as the rake of the triple trees.

This diagrams and steps should make this a little easier.

  • First install the rear wheel and a tire on your frame.
  • Now set up some kind of support under the frame (a wooden block should do just fine) and set it nice and level.
  • Determine the location of the front axle, where you want it to be (the chart will help you with axle height)
  • Using tape measure determine the distance between bottom of the trees and front axle.
  • If you want raked triple trees, then drop a rod right through the neck (broomstick should do the trick) and then measure the angle between the rod and a straight line from the bottom of your triple trees to front axle location minus offset of the triple trees.

FORK OVER STOCK (inches)

FRAME CUP TO AXLE (inches)

3 23
6 26
9 29
12 32
15 35
18 38
TIRE SIZE AXLE HEIGHT (inches) TIRE DIAMETER (inches)
300x16 11 22
250x18 11 5/8 23 1/4
275x18 11 3/4 23 1/2
300x18 12 24
275x19 12 1/4 24 1/2
300x19 12 1/2 25
325x19 13 26
275x21 12 3/4 25 1/2
300x21 13 26
500x16 12 7/8 25 3/5
500x18 13 26
400x18 13 1/4 26 1/2
400x19 13 3/4 27 1/2