Because there are a wide range of forks on the market, you'll need to measure your fork for clearance in a few different places. To do this, turn your bike upside down and remove the front wheel. Proceed to measure the following, using the pictures as reference.
1. Axle to Crown Height:
700c = minimum of 35 cm (13-13/16")
26 in = minimum of 33 cm (13")
2. Inner Crown Width
700c = minimum of 36mm (1-7/16")
26 in = minimum of 41mm (1-13/64")
3. Dropout/Fork Leg Width = minimum of 89mm (3-1/2"), measured 24mm (7/8") below the dropout
This is a more complicated measurement.
Measure from the bottom of the dropout (as pictured) down 24mm (7/8") and make a mark on your fork leg.
Now, measure across the span from the inside of the fork leg to the inside of the other fork leg.
You will need to have a measurement of 89mm (about 3-1/2") or greater.
Here is a close-up of the fork with the Omni Wheel installed.
Note how close the speed sensor is to the fork leg.
5. The last step is to measure the inside diameter of the dropout to ensure that the axle will fit in the dropout itself.
You'll want the dropout of your fork to measure at least 9.8mm (13/16") as pictured.
(If your dropout is steel and is slightly undersized, this can be relatively easily modified using a file or Dremel tool.)
Please let us know if you have any questions, and we'll be happy to help!