Originally Posted by HillRider

The choices:

1. Buy the riveted crank and remove one ring by grinding off the heads and punching out the rivets and then replacing them with bolts. For some cheap cranks, the large ring is swaged to the crank arm and the smaller ring is rivited to it so that limits your gearing to the larger ring.

2. Buy a bolted crank and remove one ring by removing the bolts. You will, however, need shorter bolts for a single ring.

3. Buy a purpose-built single ring crank.