Drilling Alloy 7/8" Handlebars
to Accept Bar End Shifters.
You will need a floor model drill press, large enough to drill a 7/8" hole in aluminum.
Also 1/4" 3/4" and 7/8" drill bits (a 27/32" bit would be nice but not necessary).
1. Drill two 1/2" holes in a piece of approx, 1-1/2" x 3/4" aluminum bar.

2. Use these holes to bolt the bar to the drill press table, with one end over the hole in the center of the table.

3. Centered, about 1" from the end of the bar, drill a 7/8" hole.
(If you use a slightly smaller drill, ideally 27/32", before drilling the 7/8" hole, you are less likely to end up with a slightly oversize hole.)

4. 3/8" from the end of the bar, drill a 1/4" hole perpendicular to the 7/8" hole.

5. Saw a slit from the end to about an inch past the hole.

6. Put a 1/4" bolt, with nut, through the 1/4" hole.

7. To accurately position the bar/fixture, run the 7/8" drill down past the flutes, then tighten the "T" bolts.

BTW I'm too cheap to buy real "T" bolts. I just file flats on the heads of 1/2" carriage bolts.

8. Insert handlebar from the bottom, through the hole in your drill press table.

9. Lock handlebar in place with the 1/4" bolt.

10. Drill with a 3/4" bit. This will give the correct I.D. for bar end shifters. (But not for most bar end brake levers,)  Don't drill any deeper than you have to, about 1-1/4" for Suntour or 1-5/16" for Shimano.

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