I have a seasoned 26" Dirt Jump bike where the time has come to replace the bottom bracket. The bike currently has Profile BMX cranks, with a single speed rear wheel (not an MTB freehub). Current BB uses external cups which means that the standard 5.5" axle is too short to tighten up correctly and occasionally have the cranks work it's way loose. With the external cups the chainline also isn't great.
Now the simple option is to go back to an internal Euro BB, but was surprised to see how expensive these are now, so was looking at my options given that 1x drivetrains have become popular. Would also give me the opportunity to go up a couple of teeth on the sprocket to 32.
Am I likely to run into any issues converting to a modern MTB crank. It looks like I can find a 73mm BSA threaded DUB BB/Hollowtech. My two main concerns are:
- What chain compatibility do I have we a 1x chainring, can I use a single speed chain?
- 1x drivetrains are common on bikes with 142 mm rear spacing compared to my bikes 135mmm rear spacing. Will my chainline be ok on a crank designed for a wider rear spacing?
update: I've found the driver on from the manufacturer. Doesn't specifically say what chains are compatible unfortunately, but I'm guessing I could measure the width of the teeth to see if a narrower multi-speed chain would work or am I oversimplifying this? link