Bicycle Mechanics - rim failure

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.



PDA

View Full Version : rim failure

MichaelW
03-31-04, 10:45 AM
Usually a problem with lightweight fancy models. My low-end, thick, heavy Rigida rims have just flared outwards on both braking surfaces. I guess a combination of braking surface wear , tyre pressure and primitive design caused the failure. My LBS says replace it ASAP, but a failure at the rear will just lock up, rather than flip me. Im using a spare wheel now.
Ive heard of rims turning into hoops, but never a braking surface flaring out. Has this ever happened to anyone before?

sch
03-31-04, 01:34 PM
Brake pads sand the rims down over a period of time and when thin enough inflation
pressure can be enough to flare the rims. Another failure mechanism is spoke pull
through at the rim, or the rim cracking aroung spoke nipples resulting in rim warp.
Steve
HarryK
03-31-04, 02:28 PM
Agree with Steve. Any rim can fail like this with enough wear, or excessive pressures. Some new rims have a wear indicator groove in the sidewall to tell you when the rim is unsafe.

Curious you say the rear will "just lock up rather than flip me". If the rim gives up, and the tire blows off at speed, I think you'll have your hands full staying on the bike.

LemondLouie
03-31-04, 04:23 PM
Usually a problem with lightweight fancy models. My low-end, thick, heavy Rigida rims have just flared outwards on both braking surfaces. I guess a combination of braking surface wear , tyre pressure and primitive design caused the failure. My LBS says replace it ASAP, but a failure at the rear will just lock up, rather than flip me. Im using a spare wheel now.
Ive heard of rims turning into hoops, but never a braking surface flaring out. Has this ever happened to anyone before?

I had it happen to the front rim on a Specialized Crosswind. The wheel had nearly 8,000 miles on it and it just kind of gave up, I guess. Of course, I didn't treat the bike like it was designed, a tour around the block, to the store, and a semi-weekly, rambling ride to the park. I put some hard miles on it. The LBS said that getting it to last that long was more than worth the price. I replaced it with a heavier Sun rim and, so far, no problems.
roadbuzz
03-31-04, 06:34 PM
That type of failure has never happened to me, but I don't ride in the rain much. I wonder if the metal in the cheaper rims is softer and less brittle, allowing it to bend rather than break off?
HarryK
03-31-04, 08:08 PM
Believe this failure is mostly a result of wear causing by the brake pads, but perhaps rider weight, road surfaces and tire width pressures would play a part.
SteveE
03-31-04, 08:28 PM
I had this happen to me with a pair of Mavic MA-40's. Thee was just too much wear on the rims from the brake pads. It gave me a good excuse to buy a new set of wheels!
Flakmonkey
04-01-04, 06:42 AM
Yes, I had a very explosive rear wheel rim failure a few weeks back, frightened the cr*p out of me, went off like a gunshot stripping an 18" section of rim completely off the wheel. It was quite an old wheel and had seen seven years of heavy daily use so I suppose I can forgive it for leaving me with a 4 mile walk home spreading a green toxic trail of tube slime behind me..

Cheers

FlakMonkey