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Thicko rim wear questions

JameyJamey Posts: 2,152
edited February 2009 in The workshop
1) If a rim does not have a 'wear indicator' groove (like my rear wheel) how do you tell when it's worn and needs replacing?

2) If a rim does have a wear indicator groove (like my front wheel) how do you use it to tell when its worn?

3) In London, how long (in miles) would you seasoned, knowledgeable people expect a touring rim like the Mavic A719 to last, roughly (I know it's impossible to say exactly, just after a vague range)?


  • robbarkerrobbarker Posts: 1,367
    You can anormally just "tell" when they go concave and look horrible. The accurate way to test is by using a vernier with pincer things on the end. A lot of people wait unti lt hey go bang, but I wouldn't recommend it!

    Average life really is how long is a piece of string. I'd expect between 5-10000 miles of commuting, but some people (like me) will ahve a 25 mile trip that involes touching the brakes one or twice, others will have a stop-start journey that will give 10 times the wear.

    When the wear indicator disapears = time to change.

    At least you know how to do it yourself now! Some advocate taping a new rim to the old one for changing rims, then swap the spokes to equivalemnt holes leaving them laced.
  • JameyJamey Posts: 2,152
    Yeah I read that, sounds like a good way to do it.

    Unless I get the upgrade bug at the same time :)
  • iain_jiain_j Posts: 1,941
    How 'concave' do you mean? Mine (Mavic A319) are definitely worn - I can feel the rims are indented where the brake pads rub - at what stage does it get unsafe? Could it explain why my brakes don't seem to have as much stopping power these days (pads are fairly new)? I've done about 2500 miles on them, most of this is out on the country lanes so not frequent braking.
  • robbarkerrobbarker Posts: 1,367
    It's difficlt to describe other than by saying it willook too worn when it's too worn. The only way to be sure is to measure it, and even then there is debate about how thin is too thin. Certainly if the thinnest part of the sidewall reaches 0.5mm (and they won't be uniform all the way round) it needs replacing. If you don't have a suitable vernier, I saw somone measure with a small G clamp once - the point on the screw thread was noted when the rim wall was clamped, and then compared to the position of the screw thread when the camp was closed tight. The other age-old method is to pump your tyre to excessive pressure and leave it overnight..
  • robbarkerrobbarker Posts: 1,367
    This is what happens if you let things go too far..

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