Chainset rings wobble

father_jack

When I spin the pedals, the chainset rings wobble slightly. The BB is fine, not loose, and the chainset is fitted to the BB axle properly. Is it likely the BB axle or chainrings/chainset is bent slightly causing this wobble? What happens is the chain rubs against the front derailler on certain gears, more so than my other Campag equipped bike. I have spent ages fiddling with indexing and no avail it is not as smooth as the other bike. I might pickup another chainset, useful to have a spare anyway. Or maybe I could convert it to double? It's a triple bike, so guess need new BB and of course double chainset. I guess front derailler will need to be adjusted but that will only require end stops to be changed?

I could try taking off the triple and bb off my good bike and trying it out on the bad one...if it still wobbles then possibly frame on the BB is out :-(

Campagnolo Mirage triple 53/42/30T

seem to have problems finding exactly the same one.

rake

my sora chainset does it a little . may be bad luck slightly untrue crank. im very impressed with the sram s350 it arrow straight maybe why its better quality. i dont think its the bb.

sungod

do all rings wobble? if not, probably a slightly bent ring - you can straighten it

does the right crank arm wobble too? if not, bent spider - probably you can straighten it

if one/both crank arms wobble, bent axle or something amiss with the bb - unlikely you could straighten it

father_jack

ok I have removed both crank arms, chainset (removed each ring too) need to remove BB. Noticed it's different to my other campag BB tool so need another BB tool

father_jack

ok I have removed both crank arms, chainset (removed each ring too) need to remove BB. Noticed it's different to my other campag BB tool so need another BB tool

Weejie54

Noticed it's different to my other campag BB tool

That's because it is a Kinex BB. You need a Shimano removal tool.

jgsi

Square taper....
The one I had was prone to the 'wobble' after replacing the crankset.
I was just extra carefull in 'knocking on' the cranks especially the drive side when replacing and tightening progressively and again carefully to the right torque.
If the BB is old then replace - it's a cartridge type? so very easy to do oneself.
If you going down to a double then you can reduce width of that BB to 108 for instance.
Maybe think of upgrading to ISIS type.... ?

father_jack

What's the benefit of ISIS? My other bike has centaur bb with this type of removal socket
http://www.wiggle.co.uk/p/cycle/7/Cyclu ... 5360041221

jgsi

ISIS designed to be stronger and longer lasting - well that was the design blurb.
Still a stepup from square taper.

father_jack

So if I upgrade to ISIS I'll need this

http://www.wiggle.co.uk/p/cycle/7/Campa ... 360039708/

and (need to check thread and axle length)

http://www.wiggle.co.uk/p/cycle/7/Truva ... 360021252/

and

http://www.wiggle.co.uk/p/cycle/7/Cyclu ... 5360041219

father_jack

woo removing chainset and chain rings has fixed the problem, chain rub has gone and so has the wobble. Perhaps the fixing bolts on the chainring were not put on equally and rings were bent one way a little? Need a proper ride but just gone up the street and so far so good.