Originally Posted by
blakcloud
You could just buy a new 46 tooth ring for your current crank and call it a day. That is of course if anything else isn't worn out.
If you do go the new crank route, as Fietsbob says, it is a trial and error method of obtaining the right bottom bracket length. My guess is no change is needed.
Thanks, it's not the 46T I'm after, it's the 30T. The 30T chain ring has a BCD of 80mm. So I would need the whole crank set. BB is sealed and in good shape, as is the chain rings. At 70, I'm trying to get into the 29-27 gear inch range. I'm at 32 inch now.
Another option I'm considering, a medium cage (I prefer 105 RD), and Shimano 14-32T cassette, will get me to 27.9 inches, at about $60. The crank set will cost me about $90, so I'll get with FSA for some details. Also, the Tempo crank set 30/46T is 9 speed, I have 7 speed in the rear. So I don't know if that will cause more issues than I need. The RD and cassette seems less costly and will work.