If so, you will have to drill them out.


Which will be a problem, because they will probably spin, the bit won't bite, and it'll ruin the crank-arm hole.


However, if you have (a friend with) a drillpress and a table vice with a vertical v-grove (not uncommon) it can be done [1].


You mount one drill bit vertically, point up, just proud enough that when the crank is placed on the table the bit bites one end of the rivet. It has to be enough proud that when you bring the upper bit, mounted in the press chuck, down on the other end of the rivet, the pressure of the upper bit pushes the rivet down on the the lower bit. This means the crank is held off the table about 1/16", you have to steady it as you start the top bit.


If the rivet spins (as it may do), stop, loosen and tap the lower bit upwards, and have another go.


[1] no v-groove? Drill a hole with the bit you're using in a parallel-sided block of something, cross-drill and tap a hole for a set screw, grind a flat on the bit. Or do anything to grab the drill - Mole grips under the table and a pair of clamps, whatever.


If you are doing a single-ring you may have to grind the tip of the bottom bit flat for top-bit-clearance.