I have a three sprocket, single piece crank and the cassette is bent/warped. Can I replace the whole thing with a single piece crank from a bmx bike? Will I still be able to use my rear cassette, which has 6 sprockets?

Thanks.

The issue is chainring thickness. BMX chainrings are designed for use with a wider chain that won't work with your 6 cog rear freewheel. The narrower chain that works with the freewheel won't fit over the thicker BMX chainring.

Thanks, the problem is the chain is rubbing against the front derailleur in the highest gear. I've tried adjusting but it hasn't helped.