Chainring frame strike

I've been experiencing a problem with my chainring rubbing against the frame in a manner which is going to do some damage to the chain stays. My diagnosis would be a problem with the cranks but wanted to check with those more knowledgeable than myself in case there's something else i should be looking into. Any feedback gratefully received...not taking too kindly to dealing with public transport...

Had a similar problem

what is the bb?

My phil wood had moved a bit and chainline needed to be reset.

Have you been tightening your cranks, Mr?

Sounds like your chainstays have lost some fitness, so they're breathing more heavily.

To clarify, it's not the cranks that are hitting the chainstays but the chainring nuts and its only a couple of them rather than all five. Am going to get the frame refurbished anyway (a couple of winters have left it looking pretty thrashed) but keen to know whether I need new cranks as well (they're old style Campy pista)

maybe your chainring isnt flat or the arms are not lined up flat. remove the chainring and place it on a flat surface.

sorry if i missed something

try geralds advice

one of my crank arms was slightly out of shape but the chainline had moved by a few mm as well, adjusting the chainline stopped the chainring bolt bit scraping

If it's that close sounds like you need a longer BB and since you're upgrading, bin those evil, crooked frame-destroying campag cranks and get some real ones. Real cranks are made in Japan. Fact.

Pics?

What BB do you have? Sounds like it's moved, so that the chainring bolts are now fouling the chainstay. Either that, or it's always been happening and you've only just noticed.

if the nuts are flatter on the side that faces away from the bike (like they were on my bike) then maybe you can take them off and put them back on the other way round and see if that gives you enough room.

but thats really just a temporary fix to stop it chewing up your frame so you can ride until you get a longer bb or whatever ;)

If there is enough clearance between crank arn and chain stays on the left (non-drive-side), you can try to put a 1, 1.5 or 2 mm washer between BB-shell and RH cup.
Perhaps you have to move the rear sprocket a bit outwards as well (washer under sprocket or move a hub axle washer from one side of the hub to the other and re-centre the wheel.

If the frame is steel:
Before the frame is going to be repainted, ask someone who has experience to make a bit more clearance (don't look when he's doing it, he'll use a hammer and a curved, round piece of steel) by "shaping" the RH chain stay. Easy to win a few mm extra.

I have 2 bikes with sugino 75 cranks and bb, there is less than 1mm clearance with both and at some time the flex has resulted in the back of the spider scraping the paint. It's gone no further than this though. They are both older track frames, maybe things were a little different back then.