Originally Posted by Germany_chris

It will work but you’ll need a new bottom bracket

Originally Posted by _ForceD_

There’s one issue you ‘might’ encounter going from a 42 down to a 34 with the small ring. The smaller circumference of the 34 changes the angle of the chain back to the gears and could cause it to snag on the large ring. I wanted to change from a 52/42 setup to a 53/38. Once re-assembled, everything ran OK in the middle gears. However, the angle of the chain from the new/smaller ring back to the smallest gear caused it to snag on the large 53 ring. So I changed the small ring to a 39 and that increased the circumference jus enough so that it doesn’t snag on the large ring. Given that you’re also going down to 50 on the large ring ‘might’ allow clearance. But it’s and issue you might run into.

Edited to add a simple drawing to help explain. Obviously not to scale, but just to show where I had the problem.



Dan

Originally Posted by GamblerGORD53

Who the HELL uses small/ small?? There is ZERO NEED.

Originally Posted by delbiker1

Assuming your 52-42 is 130 bcd, you could go to a 38 tooth small ring, the smallest that will fit on that bcd. Match that up with a cassette with lower gears to get even more low end. In regards to replacing the whole crank set, as stated above, likely going to need a new bb, only you can decide if it is worth it to you. What you are proposing is not that much cost, and relatively easy to do. I would do it if I truly thought it was going to be a plus to riding the bike.

Originally Posted by Bill Kapaun

Depending on which RDER you have, you may be able to accomplish lower gears with a simple cassette change.
OR cassette & RDER.