1. yesNoMSG said:I'm going to tap extra pedal holes to shorten the crankarms of my kid's bike. Two questions:
1. Is the tap/thread size 9/16-20? (we're talking standard pedals)
2. Where's the best place to get a left-hand thread tap in that size?
C-40 said:Is the correct thread size. It's considered a special (NS) tap.
Here's one place to get a set: http://www.bikemannetwork.com/biking/p/TL7150
You'll also need an uncommon 33/64" drill bit. A standard 1/2 inch is likely to drill too small.
If you're not experienced in machining setup techniques, you may find it very difficult to get the holes drilled at the correct distance from the crank center and perpendicular to both the crank arm and BB.