Is there something wrong with axle holes?

[Tim Gould]

Gears on bars is a dangerous game, but certainly one the works in real life. If you use e.g. a 4l bar, there's a good chance it willl fuse onto the gear and become pretty much stuck forever.

So probably the minimum cross-diameter of the hole is a bit smaller than 8LDU, but definitely bigger than 5.7LDU.

Tim