How long should a rear wheel last?
 

I was prepping my bike for a tour that starts Friday. I guess I should have done that last week because I notice cracks in the rim around two of the spoke, that were several spokes apart.



I ordered the Mavic rim in May 2008 so I probably have 7K-8K on the rim. That is touring and just every day riding miles. Touring miles on the rim maybe 2K or so.

Has this rim lived it's useful life or should I have gotten some more miles out of it?

Sounds a bit on the low side for miles to me, but there are a lot of variables. How many loaded miles, how heavy is the rider, what type of weather/road conditions, what is the spoke count on the rim, etc. I typically wear out the brake surface on mine before anything else lets go. I seemed to replace rims about every 12,000 miles (19,000 km) which was about once every couple of years. These were usually the heavier duty rims used on my utility/touring bikes. On one bike with steel rims I have never replaced the rims and it has somewhere over 30,000 miles on it. On my city bikes I use roller/drum/coaster brakes and the rims, theoretically, should last indefinitely. Race bikes all bets were off, running the lightest, lowest spoke count rims we could get away with.

Aaron :)

Cracking around spoke holes can be a symptom of a bad wheel build with too much spoke tension.

I say buy a new wheel before your tour. Sell (or give) the old wheel to anyone thinks they can squeeze some more miles from it.

Already on order. Had to paty for rush shipping but that is the way it goes.

How can I check that?

I'd also think a rim should last 20,000 - 30,000 miles of normal road use. Not sure about off-road.

Touring shouldn't harm the rim, unless you are literally loading the bike down beyond its limits.

Put a tension meter on the spokes.

Guess I'll need to pick one up or borrow one. I guess it is moot anyway. The LBS laced them up for me. They could say they were right when they went out the door.

I might try contacting Mavic to see what they say or maybe CO Cyclist where I got the wheels originally. I made the mistake of getting to narrow a gauge of spoke when I ordered the wheel and had it relaced by the LBS.

The choice of whether to replace might depend on the length of the tour and the availability of parts along the way. Personally, on a longish tour I wouldn't find it to be too big a deal to lace on a new rim assuming one was available and on a shortish tour I figure that the rim would be very unlikely to fail completely if it was showing no warning signs at the start. So unless there were some signs of impending failure I wouldn't replace a rim in preparation for most tours even if it was a multi-month tour. That said I do not tour in third world countries or other places more remote than the American West, so parts typically can be had if needed.

Cracks around the spoke holes are a sign of impending failure though. BTW, they are not necessarily the result of over tensioning.

Mavic rims typically are made from a harder and thus more brittle aluminium than rims from other brands. So, they're prone to crack, in my experience, if the wheel maker doesn't account for this.

+1 Cracks can form from loose spokes that tension and detension during rotation. The tension/detension cycle flexes the aluminum of the rim and can cause it to fail.

I saw that you already ordered a wheel, but another option would have been to just buy a new rim of the same model.

Loosen all spokes, tape a new rim (same model, thus the same spoke length) to the old rim putting the inner tube valve holes together. Then transfer one spoke from the old rim to the new rim, one spoke at a time. You obviously would have to transfer spokes from one side of the hub before the spokes from the other side of the hub. Then true it up. Takes patience, I generally budget an hour to true up a new wheel after I have it laced. Transferring one spoke from rim to rim at a time is also time consuming, probably a couple hours. It is a good way to learn without the complications of learning to lace the wheel.

I assume the rear is the one that cracked. Truing up a new wheel is much better to learn the first time on an undished front wheel, but you can learn on a back if you are a bit more patient. If it is the rear, you may want to remove the cassette first if it is covered with dirty grease.

I do not have a truing stand, for decades I have use the frame and brake pads. A truing stand makes it a lot easier, but is not absolutely necessary.

Didn't have time. I leave on Friday for a tour. But I just might do this. It would be a good skill to learn.

So I should have the spoke tension checked or at least check it myself every so often?

Or is this a constant process detension / tension? How does the wheel stay true?


And where have you been? :)

Funny, I think of that as a quick easy method. The last time I did it I think it was 15-20 minutes total. I wouldn't consider it a big problem to do the swap even on tour. The only problem is that it can be tough to find an appropriate rim when on the road. I guess if I had never built or trued a wheel I might be intimidated by it.