Rim Wear Question - When to replace?

[moose8]

On my fixed gear commuter I was changing my brake pads and noticed that the front rim, where I have a brake, and the rear rim, which doesn't, feel different even though they are the same rim (I think it's an Alex 380 but might be misremembering the number - it's definitely an Alex brand). The front rim has a noticeable "bump" on the outer circumference/where the tire seats. So in other words the brakes have worn away enough material so that I can feel a little ridge on the part where brake pads don't touch. In contrast, the rear wheel has no such ridge. Is it time to replace the rim? I know better safe than sorry, but I do like to use things up before replacing them. I don't have any calipers or anything to measure but was wondering if someone who knows more than me would think this is a no-brainer. I have used the bike through ever weather condition for a number of years so it has been subject to fairly harsh conditions.

[ultraman6970]

Aluminum rims life span is very very very long compared with carbon ones. At this point IMO depends on you if you want to swap the front one for a new one. Personally I would do it.

Doubt you will have a catastrophic fail, as i said before aluminum rims life span is very long.

Based in the type of wheel probably cheaper get a new set than fix the front, unless you know how to do the job.

[Mark McM]

Check to see if the rims have a wear indicator. These are found on most (but not all) recent rims. The wear indicator usually takes the form of small slot or dimple on the brake track, like this:

http://biketestreviews.com/wp/wp-content/uploads/2014/01/cover12.jpg

As the sidewall wears down, the indicator will eventually disappear. Do you have the same rim on both the front (with brake) and rear (no brake)? If so, then if you can find the wear indicator on the rear rim, but its gone on the front rim, then it is time to replace the rim.

[moobikes]

If your rim has no wear indicator, place a straight edge against the braking surface, and try to measure the wear in the rim. Find a ruler with millimeter marks. If it is approaching to 1mm, time to replace. If you are sure it is an Alex R380, which is a claimed, 400gm rim, the walls are going to be pretty thin.

Durability on a alu rim totally depends on usage. There is no such thing as a long long long long rim life if you commute in all types of weather.

[Louis]

I use them until the tire pressure blows out the rim sidewall.

[ceolwulf]

I use them until the tire pressure blows out the rim sidewall.


And the longer you use them, the lighter they get!

[Peter P.]

I use them until the tire pressure blows out the rim sidewall.

This is what I do, too. I haven't been stranded yet, and I've done it multiple times.

In advance of the rim splitting, you'll begin to have a "tick" when you apply the brakes. You may feel a slight pulsing as well. That's the tire pressure spreading the rim sidewall at the weakest point.

I suppose if you can place a straight edge across the rim sidewall WITH the tire inflated, and you see a small gap, you can assume tire pressure is beginning to spread the rim and it's time to replace.

[cnighbor1]

Rim Wear Question - When to replace?
On a set of well ridden MTB wheels I notice sides of rimes were bowing out just a bit at one area
The mechanic in me say no problem just clamp that area between two blocks of solid wood and press back into place Which I did Two weeks later same problem
the rims had worn thin and outward pressure of air in tire forced sides out
after new rims wheels were fine
same problem on a set of Road Campagnolo but they also were nearly were cut thru from braking wear
So if bowing out that a big clue you need new rims

[madencbm]

Having had a rim sidewall blow out on a steep descent I don't recommend waiting until this happens. Play it safe and get an new rim.

[rwsaunders]

Having had a rim sidewall blow out on a steep descent I don't recommend waiting until this happens. Play it safe and get an new rim.

+1...a fellow riding behind me at an event last year had this happen and the result wasn't pretty.

[Louis]

Having had a rim sidewall blow out on a steep descent I don't recommend waiting until this happens. Play it safe and get an new rim.

They don't do it all at once in a catastrophic failure. (Unless you ignore it and continue to ride on a failed rim.)

[JLP]

Yeah, if it's noticeably concave, don't try to get more life out of it. Exploded rims and locked wheels are no good.

Alloy rims last a long time; they wear out if there is a bunch of rain or road grit. Rims in Seattle are a wear item.

[rwsaunders]

They don't do it all at once in a catastrophic failure. (Unless you ignore it and continue to ride on a failed rim.)

I heard a rather large explosion and when I stopped to look behind me, the fellow was already sprawled on the road. After we checked on him and waited for the swag wagon to arrive, we took a look at the rim. There was about a 4-5" split right in the middle of the brake track and the track was noticeably concave. The split must have occurred at the weakest point in the sidewall.

[madencbm]

Until it happens to you the first time and the rim is covered in dirt and you are not in the habit of constantly cleaning it off and you live in the Pacific Northwest and you commute day in and day out you would be surprised how easy it is for a sudden catastrophic failure to happen. Has happened to me and others who are generally quite careful otherwise.

[Louis]

To be honest, my clincher wheels (the only kind I use) usually go bad for reasons unrelated to cracks at the brake track. More commonly it will be problems with the hub (at which point I just hang the whole thing up in the basement) or during a ham-handed attempt to true one, I'll over-tension a spoke and crack the rim at the nipple. But every now and then I will get a circumferential crack at the base of the brake track, at which point I stop riding it.

[bicycletricycle]

This just happened to me, wore through the brake track on a velo orange raid rim. Rim split, luckily I saw it start to split when pumping up the tire and not while riding.

Anyways, called velo orange out of curiosity, asked then if they have ever done any testing or have any idea what the max wear limit should be, they didn't seem to have a clear idea. My rim was worn down about a millimeter, haven't attempted to get an accurate measurement.

Long story short, be careful, email the rim manufacturer and ask them what they think is safe.

I wonder how deep those wear indicator dimples are.

[verbs4us]

In more than 40 years of riding, I have never worn out a rim at the brake surface. It wasn't until the advent of carbon rims did the very idea of rim wear become a thing. I put thousands of miles on Mavic, Super Champion, and Nisi rims--and replaced them only when the wobble could not be trued out, or cracks developed (Nisi) around the ferrules after a heavily loaded tour. To have one less thing to think about. I'll probably stick with alloy rims for the next 40 years. ("Go get grandpa! He's calling from the 7/11 and thinks he's in Roubaix!")

[Mark McM]

In more than 40 years of riding, I have never worn out a rim at the brake surface. It wasn't until the advent of carbon rims did the very idea of rim wear become a thing. I put thousands of miles on Mavic, Super Champion, and Nisi rims--and replaced them only when the wobble could not be trued out, or cracks developed (Nisi) around the ferrules after a heavily loaded tour. To have one less thing to think about. I'll probably stick with alloy rims for the next 40 years. ("Go get grandpa! He's calling from the 7/11 and thinks he's in Roubaix!")

I guess you don't do much riding in wet, gritty conditions. Most of the rims I've worn out were on MTB wheels (New England trail conditions are often wet and muddy), but I've also worn out a few road rims that have seen a lot of wet, gritty conditions. Several MTB riders I know switched from rim brakes to disc brakes, not because the disc brakes gave better braking performance, but just because they eliminate rim wear.

I haven't personally had a blow out due to a worn rim, but I've been riding with other riders when they experienced blow outs. Fortunately, none of these happened on fast road descents.

[verbs4us]

Correct, Mark. All road riding, paved surfaces and only in the rain/sleet/snow when I got caught. Lots of steep hills where I live, so heavy braking, but might help that I'm light (130 lbs). Used Mathauser pads forever--maybe they are forgiving on rim wear?

[moose8]

Thanks for all the good advice. I haven't had a chance to check my bike as I came down with something, but will check as soon as I can and snap a pic.

[cmbicycles]

Replace when you see the tube or tire bead through the rim... I had a customer bring a bike into the shop to fix a flat and the tube got cut on the hole worn in his rim. Customer was so proud of himself for wearing through the rim we cut out that section for him to save.