I used 2 nylon 1/4x20 bolts on my ole Cap 231EX to hold the gear on.
On a rough landing (sometimes not so rough):
1. The gear would sheer off the bolt heads
2. The wheel pants would punchure the wings
Sometimes the plane would belly flop on to of the gear causing fuse damage...
3. Typically this would end my flying for the day...

I ended up going back to a 4-40 with blind nut! I dunno what the right answer is, but I have yet to pull out my gear plate since switching back to metal bolts..

-Chris