I have been having a problem lately with noise from my crankset and bottom bracket. The noise subsided for a while after cleaning, regreasing, and repacking the bottom bracket, but has resurfaced. It will creak and crank when I climb or ride out of the saddle or when I apply decent pressure on the left crank arm to stop or to adjust while trackstanding. If I grab the left arm and move it, I can feel the slightest amount of play in either the bottom bracket or the crank arm. Other than this, the bottom bracket is tight and there is no noticeable play.

What I need is a diagnosis. I know this is likely to either be a worn taper on the bb spindle or worn taper inside of the crank arms, but I don't know which. I would like to keep the cranks if I can, but if I buy a new bb specifically for those cranks, and then find out that they were the problem, I may not be able to find another crankset that will give me the correct chainline, hence forcing me to get another new bb.

Should I just replace the whole drivetrain? Has anyone had this problem before, and if so, what did they do?
Thanks

What kind of cranks?

What kind of BB?

Have you checked your pedals?

Have you checked your saddle/seatpost/bars?

Have you inspected your frame for cracks?

All of those things could cause creaking, but if you found play in the cranks, then I'd put my money on that. Any way you slice it, in a battle between cranks and BB, the BB will win. Steel is tougher than aluminum. So I'd say your cranks are shot. Until you get new ones, I'd just tighten the hell out of it and try not to crank too much.

Is this lateral or rotational play? Does the left crank arm move while the right does not? If so, the crank interface is probably rounded out. If both cranks move laterally, your bottom bracket is probably loose.

Also, have you investigated other noise sources? Check your chainring bolts and your pedals.

I don't think it's the pedals, although I will take those out and rebuild them if I can just to rule it out (MKS AR2). The cranks are sugino road cranks from a Raleigh. It's hard to tell with the play in the cranks, because it is barely noticeable. Maybe I should just replace them both to start fresh.

I mostly mean the pedal threads. Make sure they're clean, greased and snug in the crank. You probably don't need to completely rebuild.

It sounds like you're looking for a good reason to replace your cranks.

if you have play on both cranks it's probably the bb. did you put the time into adjusting it when you put it back together. there should be no play on the spindle. another option is that something in your bb is shot: did you replace the berrings when you rebuilt it? if not, did any of the berrings look pitted or damaged in any way? were the berring grooves in the cups nice and even? if your berrings come in a 'race' holder thingy was it bent or otherwise mutilated?

oh, and just because flamewars are such fun: did you put jis cranks on an iso spindle? (ducks and runs)

I've been tweaking for the past day because I realized that I've been riding JIS cranks on an ISO spindle for several months, and I started getting a click/creak noise out of my crank/spindle interface.

So you may want to look into that.

or maybe you should rebuild you bb if is is ball and cup it probably needs it and a little adjustment as well