cuttboss

Procedure for removing bosses on cranks that do not have spacers. Read through the entire proceedure before starting. This procedure is for the installation of a Mountain Tamer Quad Plus in place of an existing triple chainring.
1) Remove your existing triple chainring.
2) Note whether the chainring has recesses on the outside faces of the chainring. If the chainring has recesses, measure the depth of the recess. i.e. .025"

3) Measure the offset distance

      Place the triple chainring with the outside face down on a level surface.
      Place the Mountain Tamer Triple Adapter with its triple chainring in place
      above the original triple.
      Measure the distance between the surfaces of the chainrings. i.e. .115"

If your triple chainring has recesses, add that depth from the distance measured above.
I.e. .115 + .025 = .140

This is the amount you will need to cut off of the bosses.

4) Measure the height of the bosses on the crank. Scribe this distance on the boss.

5a) Note: If you have a lathe with enough clearance, use a crank removal tool and a spindle as the means to fixture the crank in the chuck. Make sure it is completely and securely installed. Be sure to turn at low speed because it will be very unbalanced. Take light cuts. You can also use a crank removal tool to set up in a milling machine. Mount the tool in collet holder or a set of V blocks. Make sure it is secure and take light cuts.

5) Make the cuts. You can place a washer (1/2" i.d.) over the boss as a guide for making the cut. Clamp the crank securely. Use blocks of wood to protect the cranks from the vise. Cut short of the final dimension so you have some margin for error.
6) File to final dimension. Use a mill file or smooth file to cut to the final dimension. Stop at the line you scribed in step 4. That's it. You're ready to mount the adapter.
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Note: If you have a lathe with enough clearance, use a crank removal tool and a spindle as the means to fixture the crank in the chuck. Make sure it is completely and securely installed. Be sure to turn at low speed because it will be very unbalanced. Take light cuts.

You can also use a crank removal tool to set up in a milling machine. Mount the tool in collet holder or a set of V blocks. Make sure it is secure and take light cuts.