When to replace rim from brake wear?

I suppose if you know the minumum recommended wall thickness
and have a point micrometer then you could measure it but I
figure you don't have either (I know I don't). As a rule if
the brake surface feels really concave replacement would be
prudent. Some modern rims (including Mavics) have wear
indicators in them - you replace them when it shows, which
is a good idea.

I had a rim wear through on me the other day - there was an
8" split in one brake surface and a 6" in the other. Because
the rim was double walled, the failure wasn't that
catastrophic - okay I had to release the brake to get home
but the bike still went.

The symptom I'd look out for an increased tendency of the
brakes tending to grab at one part of the rim as the
weakened brake surface begins to bend outwards under the
pressure from the tyre.

Andy Chequer

"Andy Chequer" <andy@(youdontwantthisbitinit)thisisasparagus.com> wrote in
message "]news:[email hidden]...

Quoted message said:

I suppose if you know the minumum recommended wall
thickness and have a point micrometer then you could
measure it but I figure you don't have either (I know I
don't). As a rule if the brake surface feels really

concave

Quoted message said:

replacement would be prudent. Some modern rims (including
Mavics) have

wear

Quoted message said:

indicators in them - you replace them when it shows, which
is a good idea.

I had a rim wear through on me the other day - there was
an 8" split in

one

Quoted message said:

brake surface and a 6" in the other. Because the rim was
double walled,

the

Quoted message said:

failure wasn't that catastrophic - okay I had to release
the brake to get home but the bike still went.

The symptom I'd look out for an increased tendency of the
brakes tending

to

Quoted message said:

grab at one part of the rim as the weakened brake surface
begins to bend outwards under the pressure from the tyre.

Andy Chequer

Thanks, I think I will replace them just to be safe because
they have a fair amount of wear with deep grooves and its my
wife's wheels and I don't think she will be comfortable
knowing the rims could fail. Lou