Originally Posted by
samkl
Well, looks like this is going to be more complicated than I thought.
I was going to convert the FSA Gossamer triple crank to a 50/34 double. But turns out no one makes a 34 tooth chainring with a 74 BCD! So now I'm stumped. Maybe I'll have to do a 48/32, or I don't know what. It's really not straightforward, a tandem drivetrain...
I believe that Precision tandems sells both and 34 and 36 in 74BCD. I put a 36 on our gossamer triple when I converted it to a double when upgrading to eTap Red 11 speed a year or so back.
We now run a 36/50 with an 11-42 and that puts us almost right at the lowest we had with the triple while we gave up a little on the high end. If you play with the combinations in a spread sheet you should be able to see if any combination would work for you.