I´ve had an idea that I´m going to try tonight, I´ve got good quality cnc sprocket and chainring but i´m having problems getting even chain tension through the full rotation of the cranks. If you look closely at the crank/chainring, you can see that the c/ring isn´t sitting dead centre and there are gaps that vary in size between where the c/ring rests against each of the five arms of the crank.. . .anyway, I reckon that a bit of shimming from a ally can should do the job.

I´ve seen a few threads about this, different ideas have been thrown about but I´ve never seen anyone mention shimming, has anyone tried it?