catastrophic!
 

I am having too many of them. The rear 23 year old rim had taken too much braking during commuting. It thinned too much.
The RIM, not the rubber gave up. I had a blowout of epic proportions.
I was doing about five or six on good, clean, flat concrete (thank goodness) when it gave up.
Soon, I would have been doing 20 against the wind down a nice hill.
The blown rim metal caught in the brakes. It would have wrecked me out at 20 mph.
I could not walk it the 12 miles home.
This has not been a good year for my three bicycles.

boom
 

Wow. Do you do a lot of commuting in rain or sand where grit could have gotten in your brake pads, or a lot of long, steep downhills that require continuous braking?

Or, okay - I guess 23 years explains it.

two words: capital investment

Glad you're OK. That happens to high mileage rims. Brand new wheels complete are about $50 where I live, in New England.

On the plus side, you know you've ridden a lot when you wear out a rim completely. (I have not reached this milestone yet.) Next time, replace them when you start to feel concavity in the braking surface. :thumb:

Congrats. Takes quite a few miles to get through the rim on a commuter bike. Happened to me before as well. Worn through two fronts and one rear, here.
Lucky it blew when it did, when things were flat and slow.
Check your front rim, get a new rear, and get back rolling.

That's crazy! This is the worst rim failure I've ever had...second-hand rim, no idea how old it was:

https://lh4.googleusercontent.com/-I...7-no/photo.jpg

There was another place where separation was starting to occur, and several more cracks around some spokes. Thankfully, I was able to ride home. Now I'm rocking a sweet new set of wheels, hand-built by Sixty Fiver.

Wow!

Good to know you survived! Time to get another set of wheels for the commuter. As a point of pride, you belong in a pretty small group of cyclists who put enough miles and wear on a set of wheels to blow out the rims. Not that it's a good thing, since it can be dangerous. But nonetheless, a big achievement.

I've had a rim on my road bike de-laminate on me, up near the tire wall. This was after a winter of riding through slush and snow and then leaving my bike outside where it froze overnight. the repeated exposure to water/ice expansion must have fatigue in the metal around the wheel. She fell apart one morning on my way to work. It totally sucked.

Discs don't wear on rims,jus sayin'. :innocent:

True. So true. However, they did not offer disk brakes on MTBs in 1990. At least not at my price point.
My BD has disks and I am SOOOO sold on disk brakes. But the MTB and the 1984 Grand Touring rig pre-date them and are still racking up milage so I cannot justify the expense to replace them.

Bicycles are simple machines; however, they are still machines and require routine maintenance. Parts that wear, such as rims, require regular inspection for this very reason. Twenty three years on the same rims... I am certain that they have been showing dangerous wear for some time. Yes you are lucky they failed when they did...

BTW, disk brakes don't magically make dangerous failures go away... Particular when one considers that most dangerous failures occur because of lack of above mentioned maintenance.

It's hard to tell for certain from a single picture, but it appears that the wear indicator line on the OP's rim was worn smooth in some places, indicating that the rim was worn out and needed to be replaced. If so, then the incident was completely predictable and avoidable.

I wore out the original rims on my bike about 4 yrs ago. I replaced those with some Aeroheats and those lasted 13k miles before the rear blew out. I was shocked at that. Those were supposed to be good sturdy rims. Now I'm riding on Sun Rhyno Lites. We'll see how long those last. If your doing a lot of miles each year that's just one of the casualties of everyday commuting. Rims wear out just like chains wear out and everything else on a bike that you end up replacing.
http://bikeforums.net/attachment.php...hmentid=326531

Crikey! :eek: I never would have imagined rims blowing out, but it makes sense now that I think about it. Glad it happened when it did!

I'm having trouble making out a wear indicator in the pic, but a replacement rim with one would be a great idea. :)

These were vintage (23+ years) rims. I believe wear indicators on rims are more common among modern styles. However, indicators are not really necessary to determine rim wear, they are only a convenient way.

Rims, like brake pads, chains, cassettes/freewheels, etc. are all parts that wear out. If someone doesn't feel qualified to check for dangerous wear on a regular basis (yearly or more depending upon the riding distance), they should consult a mechanic to do so. We forget, since they are so simple, that bikes are machines and they REQUIRE maintenance.


What we can reasonably surmise from the OP.

At 23+ years, the failure is not the result of a manufacturing fault.

With no mention of a collision or impact, on this ride, the failure is not likely the result of such an incident.

Given the above two, and in conjunction with the age, the failure is most likely the result of dangerously excessive wear. A suitable review by a competent mechanic would have been able to ascertain such dangerous wear levels at least for the last year or two.

For those under similar situations the most likely telltale is a noticeable ridge in the rim braking area when you run your finger over it. If you can detect ANY uneven surface, the rim needs to be either replaced, or at least taken to a qualified mechanic to evaluate.

After looking again, what I initially thought was the wear indicator was the inside lip of the rim. My mistake. Thanks for the correction. :)

Thanks for sharing this. On cars, pretty much everyone understands brake pads wear out, and whatever the brake pads contact will also wear out, whether it be rotors or drums. If you are your own mechanic, you need to check your bike's brake pads and rims or rotors periodically. Rim failure after 23 years of regular use is not a surprise. Glad you weren't hurt.