Bicycle Mechanics - When to replace rims?

I have a pair of Mavic CXP21 wheels 700c, 32-hole (3x lacing) on my commuter road bike. For the last 3 years they've never needed truing until I finally broke a spoke with a poor attempt at bunny-hopping a pothole. The guy at my LBS says the rims are due to be replaced after he noticed some of the nipples were a little "stuck".

My questions:
What criteria do you use to make this judgment?
What danger am I putting myself in by continuing to ride with them?
Can I reuse the hoops to rebuild with new spokes and nipples?

I know they're not high-end, but I'd hate to toss them if they're still good for reuse.

Thanks for your input.
-Michael

The guy at my LBS says the rims are due to be replaced after he noticed some of the nipples were a little "stuck".

My questions:
...
Can I reuse the hoops to rebuild with new spokes and nipples?


I suspect that the mechanic is taking advantage of your lack of knowledge to enhance revenue for the shop. :mad: Almost stuck nipples (IOW, not stuck) do not indicate that a new rim is needed.

Also, FWIW, rims AKA hoops, so if you really needed new rims, you would not reuse the hoops (rims).;)

Other than impact damage, rims usually fail by wearing through at the brake track from abrasion or by developing cracks around the spoke holes. If you brake tracks aren't noticably worn, scored or concave and there are no cracks at the spoke holes, you should be able to continue to use them.

stuck nipples? Nothing a little tri flow cant fix.

Thanks guys.
I'll check for cracks and make sure the braking surface is not concave.

-Michael

wtf? sounds kinda shysty of the LBS. triflow works wonders and do check for brake surface damage, but stuck nipples...

I like how posters are jumping to the conclusion that the mechanic is trying to rip the OP off with incomplete information. If the hub/spokes are shyte to begin with then it might not even be worth re-rimming if the majority of nipples are rounded off/seized and if the brake track is worn.

Other than impact damage, rims usually fail by wearing through at the brake track from abrasion or by developing cracks around the spoke holes. If you brake tracks aren't noticably worn, scored or concave and there are no cracks at the spoke holes, you should be able to continue to use them.

Replace the rims before the brake track is too worn, otherwise this will happen:
http://home.comcast.net/~jeff_wills/rites2005/pages/rites042.htm

The wheel lasted 3 years. You won. Get a new wheel.

Replace the rims before the brake track is too worn, otherwise this will happen:
http://home.comcast.net/~jeff_wills/rites2005/pages/rites042.htm
I've had a couple of rims fail similarly but not nearly as impressively. Mine developed short cracks that bulged the sidewall and made braking lumpy but held together well enough for me to limp home.

Thanks guys.
I'll check for cracks and make sure the braking surface is not concave.

-Michael

Not just cracks. Look for bulging in the rims around the spoke holes. If you see anything at all other than smooth then it is stretching the metal in that area and a crack isn't far away.

I've got a set of 21's that I only used for about a year. At some point I hit something totally unnoticable that actually dented the bead flanges and also bucked the rim across about 4 spokes worth. In checking this out I noticed that a number of the nipples in the impact area were making the rim bulge noticably.

The truly odd thing is that I have no idea what I hit to do this damage. It was merely a case of riding fine one day to having a repetitive lump---lump---lump---lump---lump--- the next. From this sort of poor result I can only assume that the old 21's are a waste of aluminium. YMMV I suppose.

I have a set of those rims that came standard on a bike of mine. They lasted 3500 miles without any care before I rebuilt the rear using the same hoop and just replacing the hub. They have another 1000 miles or so on them now and are still fine. I got a great deal on another wheel set so they have become my backup/loaner set but they are still going strong. Certainly look for any bulging around spoke holes. The LBS Tech may have seen this or may just be cautious. I hate to jump to conclusions. Ask him to explain a little before you decide on any motives.

Yes, the tech might have been thinking of the labor cost, and possible need to replace all the nipples or something. He may have saw a dent or something that you did not. It might have looked unfixable to HIM. I have had bike shop reps ask me why I would want to build a wheel citing their low replacement cost. Sometimes, perhaps. Generally, nothing beats a handmade wheel.

Frequently, I am surprised at what I can fix, but have also made myself a little crazy trying to fix something that was really too much.

I get wheels with problems almost everyday and have to ask each time: Where did the spoke break? Which side? Alloy nipples? Their condition? Quality of spokes? Condition of spokes? Quality of rim (yours is good)? Dents? Condition of bearings? Condition of axle? How bent is the rim? Spokes pulling out? Excessive brake wear? Overall spoke tension? Cost and availability of a replacement vs labor and parts? Customer's budget? And so on... Wheels seem to be almost living things sometimes.

Who knows what the tech was thinking, if anything.

Generally speaking, I like your rims, IF ALL WAS GOOD, I would really try to save your wheels based on what you have said.

I like the guys at my LBS. I'm pretty sure there was no underhanded intent, and I probably missed something that he explained on top of the stuck nipples. (He'll talk all day if I let him.) I'll try and get that clarified.

For now, the wheels are just sitting in my garage and I was thinking of using the rims and hubs to learn how to build my own wheels and put my old commuter back in rotation for the winter. But if I'm going to go through those laborious and frustrating hours of building my first wheelset, I'd at least like to know that I can safely ride on them. Otherwise, I'll just have to invest in new rims for this lesson.

Thanks for the input guys.
-Michael

My question. At what point is concave, too convace.

The wheel lasted 3 years. You won. Get a new wheel.
I did. It was a good enough excuse (for the missus) for me to upgrade.

Still, being your typical Northwest tree-hugging, tofu-eating recycler...I'll reuse them if they've got some life left.

-Michael

My question. At what point is concave, too convace.
My non-scientific criterium is if you can feel the rim flex at the brake track with finger pressure, it's getting pretty thin.