Picture Page 4
Picture Page Four - Raking a fork.
There are MUCH better ways the pro's use to adjust rake on a fork - there are dies made that custom frame builders use for their bikes. There are dual bladed curved jigs in steel and hardwood that clamp both drop outs at once, and then bend the fork with an extension bar in the fork stem. I don't do that. This is a crude way that you and I can manage bending a fork without all that complex equipment.
Measuring rake - remember to subtract half the diameter of the stem. Rake is the offset of the axle from the center of the stem (the turning axis). Usually this is around 2" on the average donor fork.
I rake the fork 1 blade at a time. A piece of scrap 1 1/8" tube makes a great extension handle on the fork stem. This is the 3/4" Conduit bender tool clamped in the bench vise. Bend each blade of the fork to achieve roughly 4" or so of rake.
lay the fork on the table. Measure - this isn't completely accurate (rake is from the CENTER of the fork stem, perpendicular, measured to the center of the front wheel axle), but it is an easy relative measure.
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Checking for even bending - on a solid, level table..... You will find yourself making very small adjustments - time and again. Make them, it's worth it.
Check your fork for alignment, too. This example uses the pattern in the Mach 2 drawings - there are parallel lines for a centerline, for centering the stem over the pattern, and here in the picture the heavy parallel lines are the 100mm lines (standard hub width for a front wheel). Aligned on the grid, in this example the fork is too wide on the left hand blade.
Back to the vice. Clamped this way, very slight pressure allows you to move that left fork blade IN just a skosh.
Some forks, some donor bikes, take to this bending better than other forks. You can tell, after you've done a few, which ones are soft steel, which ones are harder. On rare forks, the blades are different, and take the bend differently, uneven. Those go in the round file (trash can). On a very few forks, the crown weld (the part that assembles the blade and stem together) is bad, and the fork merely folds at the joint when you attempt the bend. Junque. You'll get a good one, I promise.
Take the time to get the fork nice and even. The smallest of errors here will have your bike tending to turn to the left or the right, depending on it's centering error.
Adding a bridge. That's it. There are other detail shots - see the various picture pages of my bikes and of other peoples' work. Also review the "Octoberfest" page which pictured a month where I had 5 frames going in the shop at one time.
Ah, better. If you can work with two forks, do that. Good to have a backup.
