How do you decide when a chainring needs replaced?

neeb
neeb Posts: 4,473
edited May 2011 in Workshop
Obviously you can see when a chainring is showing wear because of the tooth profile, but at what point do you change it? In the past I've just done it vaguely intuitively, but it would be good to have some objective way of deciding.

Will a worn aluminium chainring cause accelerated wear in a steel chain and (indirectly) steel sprockets? Will it perhaps not cause chainwear, but increase the chance of the chain being stretched and possibly broken due to the links being forced apart?

Comments

  • Monty Dog
    Monty Dog Posts: 20,614
    Chainring teeth become decidedly pointy and 'hooked' when worn - best to compare with a new ring.
    Make mine an Italian, with Campagnolo on the side..
  • neeb
    neeb Posts: 4,473
    Thanks, yes - the problem is it's a question of degree. I never know how much wear is too much. I don't want to leave it so long that I risk snapped chains etc, or change it too soon at huge expense (both of which I've done in the past).

    What do you reckon in this case? It's campagnolo 11sp. Some teeth seem more worn than others, I'm not sure if it's just because of the special profiling for shifting, or perhaps because the profiled teeth wear faster:

    dsc3574yk.jpg
  • father_jack
    father_jack Posts: 3,509
    I've wondered could you invert the chain ring? since the wear is on one side (the right) the left side isn't worn, except for a bit of bended over metal (could file it down a bit)
    Say... That's a nice bike..
    Trax T700 with Lew Racing Pro VT-1 ;-)
  • durrin
    durrin Posts: 123
    I've wondered could you invert the chain ring? since the wear is on one side (the right) the left side isn't worn, except for a bit of bended over metal (could file it down a bit)

    nope, unless it's a single speed. All newer chainrings on doubles or triples are ramped and pinned to facilitate smoother shifting, if you flip them, the pins/ramps will be on the wrong side. You might be able to make it work, but I doubt it would be a good idea.
  • El Gordo
    El Gordo Posts: 394
    durrin wrote:
    I've wondered could you invert the chain ring? since the wear is on one side (the right) the left side isn't worn, except for a bit of bended over metal (could file it down a bit)

    nope, unless it's a single speed. All newer chainrings on doubles or triples are ramped and pinned to facilitate smoother shifting, if you flip them, the pins/ramps will be on the wrong side. You might be able to make it work, but I doubt it would be a good idea.

    I did this on a single speed and got another years use out of it but yeah, the shifting ramps would point the wrong way on a multi-speed.

    Does anyone know of a supplier who makes really basic steel 'rings with no ramps? I'd be quite happy to sacrafice a bit of weight and shifting performance (on my commuter anyway) for a quadrupling in the lifespan.

    Similarly, I was looking at an old cassette at the weekend wondering about grinding the splines slightly to put them on backwards....