74 58 | Flickr - Photo Sharing! here is a chainring adapter made out of a computer hard drive. I used a 20 tooth Sugino chainring because I had one however this leaves open the possibility of using single speed cogs these have holes drilled in them to make them lighter. At first I tried a 1.2mm thick stainless pizza cutter however it bent while I was filing it. You need 10 bolts with a platter this thick other wise it will buckle also use washers on the nuts or the notches will dig into the aluminum.. The clearance between the nuts and the crank arms are 2mm this would make it difficult to use standard bolts and nuts.This is a prototype it is still undergoing testing I took it up a 12 percent grade with a total load of 300 pounds using a 40 tooth rear and I'm still alive.
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