Rim wear indicator. Ehh... what?

SunBurnt said:

Ok! What's this thing called the "Rim wear indicator" on the rim of the wheel?

How to "read" this "indicator" (looks like some sticker or something)?

Advise please 😉
Thanks!!

When rhe brake track has worn to the point where the is a hole all the way through, you replace the rim.

SunBurnt said:

Ok! What's this thing called the "Rim wear indicator" on the rim of the wheel?

How to "read" this "indicator" (looks like some sticker or something)?

Advise please 😉
Thanks!!

Not sure what wheels you have, but check the brake track for a punched indentation.

Shimano R540 wheels, for example, have a small indentation punched into the brake track on the rim. When the rim has worn down to the level that the indentation is no longer visible, the the wear limit has been reached and the wheels need to be replaced.

daveornee said:

When rhe brake track has worn to the point where the is a hole all the way through, you replace the rim.

There are easier and surer ways to kill yourself 🙄

supergrill said:

There are easier and surer ways to kill yourself 🙄

Some rims like Mavic T520 and A719 have a small amount of material purposely removed from the inside wall of the brake track. The depth of the nearly rectangular "Rim Wear Indicator" is there to let you know the rim is worn beyond safe usage when there is a small hole all the way through.
I don't particularly like the design, but I understand it was a legal requirement.
Bontrager uses a similarly nearly rectangular material removal, but their's is on the outside... and part of where your rim brake wears away the rim. Their indication of wear to the point of no longer being safe is that you can no longer see the indicator.
A quote from Sheldon Brown's web pages:
"519 and the 520 are basically the same rim, except that the 520 has a wear-indicator machined into the inner surface. This is a small recess inside the rim. As the rim wears due to braking, and the walls get thinner and thinner, eventually this will start to show through on the braking surface, and you'll know it's time for a new rim. This is a new feature that I understand was mandated by the German government. "

I guess you might feel a little bump in the brakes as the thin walled bulge appears in the Mavic version.

daveornee said:

Some rims like Mavic T520 and A719 have a small amount of material purposely removed from the inside wall of the brake track. The depth of the nearly rectangular "Rim Wear Indicator" is there to let you know the rim is worn beyond safe usage when there is a small hole all the way through.
I don't particularly like the design, but I understand it was a legal requirement.
Bontrager uses a similarly nearly rectangular material removal, but their's is on the outside... and part of where your rim brake wears away the rim. Their indication of wear to the point of no longer being safe is that you can no longer see the indicator.
A quote from Sheldon Brown's web pages:
"519 and the 520 are basically the same rim, except that the 520 has a wear-indicator machined into the inner surface. This is a small recess inside the rim. As the rim wears due to braking, and the walls get thinner and thinner, eventually this will start to show through on the braking surface, and you'll know it's time for a new rim. This is a new feature that I understand was mandated by the German government. "

I guess you might feel a little bump in the brakes as the thin walled bulge appears in the Mavic version.

The Velomax Circuit Comp rim has a groove machined right in the middle of the braking surface and painted black. I'm guessing this is a wear indicator feature also, but haven't found any info about it.

Julian Radowsky said:

Not sure what wheels you have, but check the brake track for a punched indentation.

Shimano R540 wheels, for example, have a small indentation punched into the brake track on the rim. When the rim has worn down to the level that the indentation is no longer visible, the the wear limit has been reached and the wheels need to be replaced.

Ah! Yes, closer inspection on the brake track did say something like what you described 🙂

One question is, the brake track is so solid! Can the rubbery brakes really wear it down? I am quite skeptical about it 😄

SunBurnt said:

Ah! Yes, closer inspection on the brake track did say something like what you described 🙂

One question is, the brake track is so solid! Can the rubbery brakes really wear it down? I am quite skeptical about it 😄

Sure, the brake pads on your car wear out the cast iron rotors, and they are a lot harder than the aluminum of your rims. The rim face may look solid, but it's made as thin as possible on most high-end rims....to save rotating weight and sell to the gram counters. Wear is critical because the rim has to withstand the high tire inflation pressures without failing; most are rated for "only" 140-150 psi when new. When the sidewall wears too thin, the rim can crack under high inflation pressure and/or bumpy road stresses...not what you want to happen of course.

Believe MAVIC offers ceramic-coating on some of their rims which ought to fix this problem. They cost more, but may be worth it if you have to brake a lot. Of course, they'll still crack and fail eventually due to fatigue like any rim.

dhk said:

Sure, the brake pads on your car wear out the cast iron rotors, and they are a lot harder than the aluminum of your rims. The rim face may look solid, but it's made as thin as possible on most high-end rims....to save rotating weight and sell to the gram counters. Wear is critical because the rim has to withstand the high tire inflation pressures without failing; most are rated for "only" 140-150 psi when new. When the sidewall wears too thin, the rim can crack under high inflation pressure and/or bumpy road stresses...not what you want to happen of course.

Believe MAVIC offers ceramic-coating on some of their rims which ought to fix this problem. They cost more, but may be worth it if you have to brake a lot. Of course, they'll still crack and fail eventually due to fatigue like any rim.

Just wondering if my front tire blows, does it go "pop" and the next thing I'll find myself on the road surface? Or will it start to lose air but I still have control of the bike??

Wanna make sure I know what the heck will happen when I get my first blown tire :eek:

SunBurnt said:

Just wondering if my front tire blows, does it go "pop" and the next thing I'll find myself on the road surface? Or will it start to lose air but I still have control of the bike??

Wanna make sure I know what the heck will happen when I get my first blown tire :eek:

I've never seen anyone crash due to a flat. Even with a fast deflation, clincher tires seem to stay on the rim until you can get the bike stopped.

Actually, just had my first on-the-road flat of the season on Saturday. I was in a small group, and hit a pothole at about 20 mph. My buddies ahead didn't see it in time to call it out; I slammed it with some weight on the handlebars since I didn't see it coming. (Usually you get a chance to unload some weight or bunnyhop over the pothole....if you can't go around it.)

Anyway, the impact pinch-flatted the tube, which looks like a "snakebite" puncture...two holes on either side of the tube from the rim impact. Took me about 1/4 mile to notice the front tire was going down; so plenty of time to pull off the road and fix it while the guys stood by and debated the fine points of various pumps and CO2 inflators.

SunBurnt said:

One question is, the brake track is so solid! Can the rubbery brakes really wear it down? I am quite skeptical about it 😄

Think about road/trail grit on the pads/brake surface.