chainring movement on downward stroke rubbing on front mech

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daffyavfc
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chainring movement on downward stroke rubbing on front mech

Postby daffyavfc » Mon Dec 24, 2012 23:17 pm

Hi

My ribble roadie has a compag xenon triple crankset and moves outwards slightly on the right down part of its revolution causing it to rub on the outer side of the front derailleur. Do I need a new crankset or just the chainring as a new triple square taper in compag will cost me £80.

Is it as simple as removing the crankset then checking each chainring or could the cranks be offset?

Any help appreciated

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Monty Dog
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Re: chainring movement on downward stroke rubbing on front m

Postby Monty Dog » Tue Dec 25, 2012 09:50 am

Firstly, check chainring bolts are tight or if the chainring is bent - unship the chain and turn the crank slowly by hand and check the gap with the front mech cage. Next, push/pull the crankarm to see if there's any movement - there should be no detectable movement - if there is, something is loose or worn. Finally, it could simply be due to a flexy frame - stand beside the bike and press down on the lower pedal with your foot to see how far the frame flexes under load.
Make mine an Italian, with Campagnolo on the side..

daffyavfc
Posts: 193
Joined: Tue Jan 03, 2006 14:13 pm

Re: chainring movement on downward stroke rubbing on front m

Postby daffyavfc » Thu Dec 27, 2012 07:56 am

Hi

slight bend in chainring so gently tapped it back into place with hammer and small chisel.

#PROBLEM, it requires a special Campy tool to remove the BB (Xenon) thats looks like a round disc with little balls attached to it. Does anyone know where I can get a cheap one from as the Campys are not cheap.

Should have checked all of this when buying a bike that is full Campy when all my tools and experience is with Shimano, schoolboy error!!

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ugo.santalucia
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Re: chainring movement on downward stroke rubbing on front m

Postby ugo.santalucia » Thu Dec 27, 2012 09:50 am

Might be wear of the BB bearings, as you have square taper... do you have room for adjustment, or they are a cartridge that you can't touch?

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g00se
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Re: chainring movement on downward stroke rubbing on front m

Postby g00se » Thu Dec 27, 2012 11:38 am

daffyavfc wrote:Hi

slight bend in chainring so gently tapped it back into place with hammer and small chisel.

#PROBLEM, it requires a special Campy tool to remove the BB (Xenon) thats looks like a round disc with little balls attached to it. Does anyone know where I can get a cheap one from as the Campys are not cheap.

Should have checked all of this when buying a bike that is full Campy when all my tools and experience is with Shimano, schoolboy error!!



I think this should do it.

http://www.ebay.co.uk/itm/Park-Tool-BBT ... 337c6180ca

daffyavfc
Posts: 193
Joined: Tue Jan 03, 2006 14:13 pm

Re: chainring movement on downward stroke rubbing on front m

Postby daffyavfc » Thu Dec 27, 2012 20:28 pm

thanks

I've ordered the above tool, thanks for your help.
Is this a standard fit tool for Campy BB's?

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Monty Dog
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Re: chainring movement on downward stroke rubbing on front m

Postby Monty Dog » Thu Dec 27, 2012 21:08 pm

That's not the right tool - Xenon triple uses a cartridge bottom bracket which requires a Park BBT-5
Make mine an Italian, with Campagnolo on the side..

daffyavfc
Posts: 193
Joined: Tue Jan 03, 2006 14:13 pm

Re: chainring movement on downward stroke rubbing on front m

Postby daffyavfc » Thu Dec 27, 2012 23:48 pm

this is what I'm trying to take off so the bbt4 should fit should it not?

http://www.cheapbikeparts360.com/produc ... m-bracket/

daffyavfc
Posts: 193
Joined: Tue Jan 03, 2006 14:13 pm

Re: chainring movement on downward stroke rubbing on front m

Postby daffyavfc » Mon Jan 07, 2013 19:29 pm

Hi

it is definitely just the front chainring, 52T, it needs changing as not straight. My tapping away with a hammer has not done enough as still rubs on the front mech during the downstroke when pedalling hard.

Can I buy any old campy 52T chainring that has the same BCD as the one I'm taking off? :?


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