Chainring rubbing against the chainstay. Solution???

spocky

My inner chainring (part of a double) was a couple of mm away from chainstay when I fitted a new bottom bracket (mirage 111mm English thread) and chainset.

Now after a few hundred miles it is rubbibg against the chainstay.

Is there any other soultion to this other than buying a new longer bottom bracket.

I was thinking about getting the triple mirage BB at 115mm and puting my doublechainset on it to try and stop it rubbing.

maddog 2

you could:

1. fit a smaller ring (may not be possible or ideal)

2. space the BB with a spacer on the driveside (which would bring the non-driveside arm nearer to the chainstay on the other side, and you'd be a tad asymmetrical but this probably would be unnoticeable). I'm assuming the BB has a lip on the driveside, like Shimano BBs

3. fit a wider BB axle, as you say

4. hit the chainstay with a large hard thing to make a dint to give more clearance (bit drastic I know but I've done it on a commuter before now)

5. can't think of a five

spocky

AM INTERESTED IN YOUR NUMBER 4 SOLUTION AS IT IS A STEEL FRAME. HOW DO I DO IT WITHOUT DAMAGING THE FRAME OR MAKING IT WEAKER

DON'T WORRY I WON'T HOLD YOU LIABLE IF I DO IT AND IT DOESN'T WORK.

COULD YOU EXPLAIN A BIT MORE ABOUT USING A SPACER. WHERE YOU GET ONE HOW YOU DO IT.

STUART

maddog 2

your LBS should have them. I've got a couple and they are 2mm wide with an inner diameter of 35mm.

If you have no luck then I'll send you one.

As for purposefully denting a frame, you just mark where you need the dent, aim well, and clout it with a hammer. Takes a bit of nerve but it's cheap

maddog 2

the spacers that come with HT2 BB cups should also do the trick I reckon

Monty Dog

Some cassette spacers work fine as BB spacer. Your LBS should have some - many of todays integrated chainsets come with spacers to accommodate undersize BB shells. To install, remove cranks and BB - install spacer on fixed/drive-side of BB and refit cranks. Make sure that there is sufficient clearance on non-drive side between end of crank and chainstay.

Suggest you don't try number 4 without supporting the inside of the chainstay, otherwise you could just distort the alignment of the frame or even worse crack the stay.

Ken Night

spocky wrote:

Is there any other soultion to this other than buying a new longer bottom bracket..

You may need to understand why this is happening before you bash the chainstay with a hammer ....as it may not solve the problem

Is the pedal end of either crank, very close to the chainstay?

If so,

1 you may have "widened" your square taper (quite common if you have changed the cranks from bike to bike or from Campag onto a Shimano BB) which means the crank will be closer to the middle of the bike

2 alternatively, you're using a bike with a wide section seat tube-not all builders think this through properly

Either way you need a longer axle-and of course AFAIK, Campag don't do one

Try TA who make nice light ones with long axles. Let us know how you get on?

maddog 2

spacers are 2.5mm wide actually, so you'd need at least this much clearance between your non-driveside crank arm and the chainstay, otherwise you'll just move the problem to the other side of the bike...

redvee

The spacers are AKA freewheel spacers as BB and freewheels share the same thread diameter and I think pitch, 1.37" x 24tpi. I've got one on my BB at the mo to adjust the chainline on my SS, like you if I run the c/ring on the inside of the spider I'd have a groove in the c/stay.