I have V-brakes and my rear pads wear more at the leading edge. I'm very careful to set them up when replacing. My question is would it be any problem if I reverse them after they've worn a bit, i.e. swap the left pad and right pad so the leading edge becomes the trailing edge? Has anyone tried this?

For a start, you're talking about your back brake, so even if it does make a difference it shouldn't matter.

I'm a bit sceptical about whether 'directional' pads really care which way they're facing, unless they're made of something special... although the grooves may serve to eject debris better in their intended orientation.

I say go for it. Most pads are just plain flat. And those like Koostop pads that have the little angled wiper don't wipe anything once they've worn that bit off. As for the grooves I seriously doubt they do much. Angled to eject flotsam or not they all end up packed with goo anyway. Some might suggest that the longer leading side is to even up the pressures. But if that worked then the wear should be even as well. And as you've found that sure isn't the case.

So flip away and let us know how it goes.

No problem reversing inserts if you think it'll help, but remember that you can't reverse the holder because the closed end has to be to the front. Otherwise the pad may eject when you apply the brakes.

FYI- perfectly adjusted pads would tend to wear most in the rear, because of the torque applied by the forward moving rim. That's why Kool Stop moved the mounting bolt forward (or lengthened the back depending on how you look at it). If the front of your pads are wearing more than the back, you probably have too much toe-in, and should remount the shoes more parallel to the rim.

Think about a brake booster arch , they wear that way because the braking forces are torquing the frame tubes.