How Do I Check For Rim Wear

[G-Zero]

A couple of years ago I was on the return leg of a long leisure ride when I suffered what I thought was a rear puncture.

On closer inspection, I found that the braking area of my rear wheel rim had worn thin and the rim wall had broken away from the main body of the rim, ending up with me having to call for transport.

The bike and wheel had done a lot of miles, but there was nothing outwardly obvious to me to indicate that the rim was wearing through.

I'm now putting more regular and longer miles in and would not like to suffer something like this on a commute, so is there a way of checking the remaining thickness of material left on the rim wall and is this a common occurence.

 

[HLaB]

Its happened to me once, so touch wood its not too common. On some rims there are rim markers (usually a black strip round the rim and when that disappears the rim is worn. Other wheels don't have this and you have to measure with calipers. I've not read it all but this is a ctc article on it.

 

[andrew_s]

Most current rims will have a wear indicator somewhere (they are compulsory in Germany). It may be a groove in the braking surface (sometimes filled with paint) that wears away with the rim and vanishes, or it may be a cavity within the rim that is exposed when the covering material is worn away. Unfortunately each brand of rim is different, because of patents.

Probably best are Rigida, which have a full circumference cavity on both sides - impossible to fail to notice or to ignore (below)

In the absence of an indicator, use a gauge like this one that will reach underneath the hooked edge of the rim. Replace when it shows 1.0mm thickness. I've found that the rims break at about 0.7mm (~100psi, 28mm tyre).

[edit]
When the rim is about to fail, you often get a short section cracking free first and bulging enough to knock on the brake blocks in the same way as a pothole-dented flange would. Let half the air out of the tyre, and ride directly home - slowly without using the brake on the affected wheel if at all possible, perhaps undoing the brake release or adjuster to stop the knocking.

All rims wear. The rate depends on your brake blocks and whereabouts you ride, sandy soil being worse than peaty soil. Shimano blocks are worse for wear than Koolstop.
In the worst case, you can wear out a rim quicker than the front tyre (~6000 miles)

 

[Tynan]

whem the tip of my thumb can fit into a groove on the rim is my pay attention time

quite often because of my 15st brake heavy daily commute

 

[Scoosh]

I have been told (by trustworthy experts) that the braking surface on a rim** should be flat - not concave.

Put a straight-edge on the rim (from tyre towards hub) and if you can see daylight through any gap - be careful.

If it's quite concave - replace rim.

**EDIT: some rims, including mine

 

[snorri]

Having read the opening posts in this thread, I thought I'd better check!
My front rim is a Mavic, and there was a little dimple on each braking surface just beside the Mavic label opposite the valve. After Googling "Mavic rim wear indicator" and inspecting the inside of the rim I realise that this dimple will become a hole after a little more wear.
Time to consider my options.

 

[Mad at urage]

I have been told (by trustworthy experts) that the braking surface on a rim should be flat - not concave.

Put a straight-edge on the rim (from tyre towards hub) and if you can see daylight through any gap - be careful.

If it's quite concave - replace rim.

Some rim makes (don't ask me which - I could go check mine, but there'll probably be others) are concave when new, so that is not a generic solution.

 

[Scoosh]

Having read the opening posts in this thread, I thought I'd better check!
My front rim is a Mavic, and there was a little dimple on each braking surface just beside the Mavic label opposite the valve. After Googling "Mavic rim wear indicator" and inspecting the inside of the rim I realise that this dimple will become a hole after a little more wear.
Time to consider my options.

I believe that some Mavic rims have wear indicators , others don't .

My Open Pros don't