Hi everyone!

I am riding a 1989 Trek 520 and I am looking to replace the bottom bracket. However, I am not sure which bottom bracket size I need to get. Do any of you have an idea of what Width/Length numbers I am looking for?

If it makes any difference, I am using a Sugino XD600 Crank.

Thanks!

You could probably pull your cranks off and measure it. It likely has a 68mm bottom bracket shell, and the XD 600 takes a square taper BB spindle. Measure it to make sure, but I'll bet it is a 110mm. I run an XD 600 on my cross bike, and I believe that is what I got when I replaced the BB.

Best to get the BB with the crankset, the seller should help you.

M730, as a single speed ive used a 118,
for middle chainring chainline, on rohloff bike a 127.5 BB is right

And with wide chainstays, the arms clears the frame better.

very low profile cranks are designed to come in and meet a shorter BB.

IDK, about the specifics of Sugino XD600 Crank, not owning one.

My LBS does not put much of an upcharge on BB's when compared to the internet. I'd leave it to the pros if you don't have the tools to pull the cranks and measure the spindle length. It will be 68xsomething, though.