Living Car Free - Rim Failure Question??

A piece of another thread got me thinking.

Paul H wrote "In the winter, when there is salt and sand on the roads, rim brakes require frequent pad replacement and rapidly wear out the front wheel. This is a particular problem when the front wheel is an expensive handbuilt unit with a hub dynamo built in."


Have any of you car free people had a front wheel wear out where it was due to the road abrasives? What are the symptoms? Does it occur suddenly or does it give you a warning? If it occurs suddenly should I be measuring the rim with calipers and replace the wheel after ## micrometers has worn away?

I ride all year almost everyday and haven't yet replaced the pads on my two year old bike. We city people probably use our brakes a lot more than suburban path commuters. Since I wait until the brakes start making a funny noise before checking the pads I probably abraid my rims more than I should.

You can measure brake surface wear with a micrometer if you want-I believe the rule of thumb is to replace the rim when the brake surface gets worn to less than 0.5mm thickness. Or by observation, look/feel for a concave brake surface and cracking. In practice, I wouldn't worry that much. Just ride it until it fails, then replace the rim.

You're overdue for new brake pads. It's an easy job. Even I can do it! :)

Those green scouring pads work great for cleaning the gunk off rims. I just use a dry one and it cleans them right up.

I've ridden my bike for two years, and I've gone through a couple sets of brake pads. They do seem to wear out more in bad weather. The rims are fine, though, probably because they're so much harder than the pads. I don't worry about the rims at all.

I had a rear wheel explode in winter due to sand wearing down the sidewalls. It made a slight ticking sound for a few hundred meters and then just peeled apart. I now use disc brakes for my winter bike.

My experience, back when I was commuting on my Specialized Crossroads, was that a rim lasts one winter and a set of brake pads lasts one month.

Symptoms: you can see it is getting worn down -- micrometer not required. It is a gradual process. Wear on both pads and rim is very low except for winter.

Paul

My experience, back when I was commuting on my Specialized Crossroads, was that a rim lasts one winter and a set of brake pads lasts one month.

Symptoms: you can see it is getting worn down -- micrometer not required. It is a gradual process. Wear on both pads and rim is very low except for winter.

Paul
This is incredible. I rode two winters 2000-2001-2002 Mt. Pleasant - Alexandria through the city, about 10 miles but had to go longer through crystal city in the snow since they don't clear the path. Same rim. Maybe I changed pads once. From 2001 to 2004 the same bike was my bad and often good weather bike but only commuted a few miles in the city. Same old wheel. The bike was a trash bike that I fixed up so who knows how much riding it had before that. I fixed up a Fuji touring bike from the trash with an old looking rim, gave it to a car free friend who used it as the foul weather bike, she gave it to another friend's teenage son who now uses it to get around. I changed pads on it but that is it. The rim looked old when I pulled it from the trash. It was definately set up for touring with a nice aftermarket rack and handlebars and was well used, I had to replace the derailleur. A new wheel per year really adds to the cost of car free. My maintenance rule is if it isn't making noise or slowing you down or affecting handling, don't muck with it.

i'm hoping my fixed gear will alleviate this problem this coming winter. If you don't use the brake you can't wreck the rim.

I would think rim-material, and the particular region's choice of road de-icing compounds has a big impact on this.

Have any of you car free people had a front wheel wear out where it was due to the road abrasives? What are the symptoms? Does it occur suddenly or does it give you a warning? If it occurs suddenly should I be measuring the rim with calipers and replace the wheel after ## micrometers has worn away?



yes I have, and it gets replaced twice a year, when it gets cracks in the sides from being worn away by the brake I get a new one

yes I have, and it gets replaced twice a year, when it gets cracks in the sides from being worn away by the brake I get a new one
Thanks. So I should look for cracks when I replace the brake pads. I suppose that cracks would make the brakes feel and maybe sound different too. On my current bike I can feel the weld mark rub when the brakes slide over it.

they dont feel different really, or sound that different, but the cracks are hard to miss, last one I had went about 3/4 the way around on one side, some rims are better than others, and brake pads definitely vary alot

Brake Pad Rim Wear (http://www.stc-law.com/bikebrakes.html)

yes I have, and it gets replaced twice a year, when it gets cracks in the sides from being worn away by the brake I get a new one

This is amazing to me. I maintain bikes ridden by 5 different people that are used for commuting, training, and racing. I have replaced two rims because of wear in 10 years. I have never had one fail from rim wear.

This is amazing to me. I maintain bikes ridden by 5 different people that are used for commuting, training, and racing. I have replaced two rims because of wear in 10 years. I have never had one fail from rim wear.
Is there a harsh winter where you live? If so, does the city use sand on the roads? I find it's the sand that kills rims.

Brake Pad Rim Wear (http://www.stc-law.com/bikebrakes.html)
Nice link. When Pedex said cracks I imagined radial cracks. It is beginning to make sense. The idea about holding a straightedge up to the rim when you change a tire seems easy enough. The article is talking 10 years for normal bike enthusiast rims. But if Pedex rides like some of the bat out of hell DC messengers, I imagine he does more heavy braking in a day than I do in a month. Some of those guys and girls seem to be always either accelerating or braking and no in between except when they're talking to the dispatchers on their radios and even then they blow right by me.

It is entirely due to the sand that they dump on the roads. The Washington DC area does really intensive salting and sanding of the roads.

Paul

This is amazing to me. I maintain bikes ridden by 5 different people that are used for commuting, training, and racing. I have replaced two rims because of wear in 10 years. I have never had one fail from rim wear.

Take the average amount one of those people rides, now multiply it by 5 or 6, then take into account Im doing about 30 runs a day with a minimum of 2 stops per run. I get about 6 months or about 7000 miles out of a front rim, slightly less in winter. I spend about 1/2 to 3/4 of that time out of the saddle either accelerating or slowing down, usually about as fast as I can.

Ive had all kinds of things break that shouldnt:cranks, chains, hubs, rims, pedals, handlebars, the job isnt easy on man or machine.

Take the average amount one of those people rides, now multiply it by 5 or 6, then take into account Im doing about 30 runs a day with a minimum of 2 stops per run. I get about 6 months or about 7000 miles out of a front rim, slightly less in winter. I spend about 1/2 to 3/4 of that time out of the saddle either accelerating or slowing down, usually about as fast as I can.

Ive had all kinds of things break that shouldnt:cranks, chains, hubs, rims, pedals, handlebars, the job isnt easy on man or machine.

I wasn't questioning or disputing. I just find it amazing. Some of our rims have had tens of thousands of miles on them with very little discernable wear. But most of those miles probably don't include all the stopping you are doing.

I don't ride a tenth as much as pedex, but i do ride a lot, pretty much every day of the year, in a northern climate, with a lot of stop and go. My city sands and salts roads. I also do some off-road riding on easy single-track, maybe once a week.

I replace front brake pads about twice a year and rears about once. My hubs look good after three full winters. A mountain bike like mine might have thicker rims than a road bike?

How about steel vs aluminium rims? My "beater" has steel rims, and they just get polished silver from the breaks. The newer aluminium rims I have are a pain in the rain even. Sand from the road gets on the rim and then just grinds when I break. I have black/grey all over my tires from the rims in the rain. I wipe it off and clean the break pads after each rain to try and minimise the wear.

How about steel vs aluminium rims? My "beater" has steel rims, and they just get polished silver from the breaks. The newer aluminium rims I have are a pain in the rain even. Sand from the road gets on the rim and then just grinds when I break. I have black/grey all over my tires from the rims in the rain. I wipe it off and clean the break pads after each rain to try and minimise the wear.
What is that black/grey stuff? Is it powdered aluminum material rubbed off the rim? I thought it was road or brake pad gunk. Now that you mention it I don't remember it on the steel rims.

I burn through brake pads (replace monthly in winter?), but haven't really seen detectable rim-wear.

As far as I can tell, it is definitely metallic and not rubber powder. Not sure how to test if something is aluminium. Magnets don't work :-)

Maybe I am just noticing it more because this bike has light sidewalls and the beater has black ones.

I live in Finland and do all my moving about by a mountain bike with V-brakes. We have a long cold winter, with lots of snow/sleet/rain, and sand is spread on the streets in the cities in the winter.

The fastest ive worn out a pair of new brake pads has been two weeks..this was when weather was close to 0 celsius, alternating between frozen and wet weather, with lots of fine-ground sand on the ground mixed with slushy snow. You could see the pads wearing out from the red gunk they left on the rims. I also clean the rims every day with soft cloth when the weather is bad, this helps somewhat. Some (cheap) brands of pads also seem to collect bits of metal and sand in the pad material, and this of course is bad for the rim also. And even with regular cleaning and changing pads I had to replace both rims after 2 years (thats 2 winters) of commuting use. Now I have better rims also, originals were some cheap Spectras, switched to Mavic rims and they seem to take breaking a lot better, theyve worn a lot less. The 2 year-old rims were down to 1/3 of their wall thickness and were concave in the middle of the surface, so much that I started to get afraid that theyd break one pretty day :)

Another thing to watch out for with the sand/rock salt: If you make a fast banked turn and hit a patch of it, you'll slide out. I got a beautifully bruised rib that way last winter.

It's kind of funny that we're talking about this topic in the dog days of August! :)