2004 m50dx bottom bracket
 

Hi,
Does anyone know the stock BB for a 2004 m50dx ?
I've spend days searching the internet with no luck.
I purchased a used 2004 M50 DX of craigslist for $125 and I love it. The only issue is once I had it tuned up at a shop I noticed a grinding sound that sounded as if the BB was going bad. I took it back to the shop and they told I must be riding "between gears".
It always makes a grinding sound on the down thrust of the right crank.
Anyway, I believe I need to replace the BB but can not determine the BB size.
Any help would be greatly appreciated.
I was going to try Raleigh customer services and see if they can help but I figured I try here first.

I used to own this bike and am selling the BB and crank on the CL right now. Mine was a 68x113mm ISIS drive.

have you tried lifting the chain off to the inside, letting it hang on the BB shell?
spin the crank, listen for noise. move crank slowly to 'feel' for roughness.
check the pedals the same way.

I haven't lifted the chain but I will asap. Thanks for the info.
If it is the BB I'm pretty sure it's a 68mm X either 111 or 113mm with a square-taper.
Bottom Bracket SET SHIMANO BB-UN54 68X113-ENG SEALED. $26.98 on Amazon.

Well, I lifted the chain and was surprised not to hear or feel and sounds or grinding from the BB or the pedals. My next guess is that the chain has stretched and need replaced. At least, I hoping that it's just the chain and not the cogs.