Crank Tap???

What does a crank tap do? I think it removes the threads from a crank where it connects to the pedal so that you can locktite in a reverse thread. Is this correct or am I an idiot?

Crank Tap(doesn’t show picture):

A tap is a hand tool that cuts threads into a drilled hole. If you want a threaded hole, the process is:

  1. Drill hole in metal of the exact size specified for your diameter and thread size

  2. Twist the tap by hand in and out of the hole until the threads are created.

This is hard to explain, you would probably need to have someone show you how the first time. It is very important to use the right size drill for the hole: too big and your threads will be insufficient, too small and you will break off your tap in the hole.

I imagine that you would also need to buy or borrow a handle for the tap, typically a tap is square on the end and is mounted in a simple T bar type handle. Do a google search for Tap and Die, probably you can find pictures that will be more helpful than I have been.


Re: Crank Tap???

Yes. :wink:

It’s a way to convert a left crank arm into a right crank arm.

The tap cuts out the old threads and leaves an oversized hole with new threads for the helicoil. You screw and glue the helicoil in and presto - you have a spiderless right crank arm.

This can be a bad idea. Some crank arms doen’t have enough material around the crank arm to begin with. When you cut the hole for the helicoil you weaken this area even further. The risk is that you’ll snap the crank right at the pedal hole. It’s a classic failure in older bike cranks.

On the other hand, it’s a way to make a set of unicycle cranks from a mis-matched set of high-end bike cranks, so it is a useful thing to have in a well equipped unicycle shop.

cool thanks!