Join Date: Sep 2005
Location: Hatfield, PA
Bikes: '64 Schwinn Traveler, '73 Astra Tour de France, '79 Fuji Gran Tourer, '86 Dahon folder, '94 Specialized Hardrock, '95 GT Timberline, 2005 Jamis Aurora
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Take the top cap off of your stem, and measure the INSIDE diameter of your stem. This is the same as the OUTSIDE diameter of your steerer tube. Measure it again, and then write down the measurement.
Place a ruler alongside the middle of your headtube, in a straight line form top of your stem to the bottom of the headset's lower bearing cup. Verify that the ruler ruler is parallel with the headtube, and check your measurement again. Write the measurement down.
Meaure the distance from the top of your stem to the top of your steerer tube. Verify your measurement, and write it down. Now subtract it from the previous ("along the headtube") mesurement. The difference is your steerer tube length. (It might be a few millimeters off, but it will be close. If you're only replacing your fork then you will directly measure the old one after you've taken it off, bfore cutting the new fork's steerer tube. It gets more complicated if you're replacing the headset, etc. with the fork.)
Put the top cap back on, and tighten gently. (The bolt in the middle of the top cap is only for preloading your headset. It only needs to be tight enough to hold the top cap on. The clamping force of the stem around the steerer tube holds everything together, except the top cap.)
Last edited by spunkyruss; 04-07-06 at 12:42 AM.