Bicycle Mechanics - I thought I needed a wheel truing (pics attached)

Hello All,

I have about a 20 mi commute each day, I don't do jumps or rough riding. I have a bontrager select rim. I recently had the rear wheel trued 2 weeks back. I was riding my bike on my commute and I noticed a strange sound, it was my rim rubbing up against the brake pad. I had to wait till I got back home so I can inspect it further. This is what I saw:

http://img454.imageshack.us/img454/2657/cimg08134il.jpg

I have no idea as to how this could of happened because all I do is normal riding. I had this rim for about 4 months. Could the mechanic tightened too much while truing the wheel? I'm open to any suggestions or comments. Because I don't really know what to think. Is it repairable? Will I have to get a new one?

Thanks

Perhaps the mechanic didnt use a tensiometer when trueing the wheel. Some people have had trouble keeping these true, particularly if they are heavy.

http://www.roadbikereview.com/cat/wheels/wheelsets/Bontrager/PRD_104397_2490crx.aspx#reviews

Eyelet tearouts happen. It may be a weak spot or an over tensioned spoke or unevenly tensioned spokes. I'd suspect that, given the paired spoke of this kind of wheel, that the spokes have to take a lot of load to keep the wheel together. Aluminum isn't the best material to take this kind of load and, with normal wheel flexure, it would eventually tear out. That's one of the reasons I don't ride boutique wheels.

It's not repairable. You need a new rim. Sorry.

A similar thing happened to me a couple of years ago with a rim manufactured by Rigida. It's bad news I'm afraid - the rim is dead as cycommute said.

Since then I have had very good reliability from Mavic rims, specifically CXP33 and CXP21. Both are very tough and need very little attention once the wheel has "settled in" after the first few rides.

Cheers,

Ed

Yeah, needless to say its a real bummer. :(

A similar thing happened to me a couple of years ago with a rim manufactured by Rigida. It's bad news I'm afraid - the rim is dead as cycommute said.

Since then I have had very good reliability from Mavic rims, specifically CXP33 and CXP21. Both are very tough and need very little attention once the wheel has "settled in" after the first few rides.

Cheers,

Ed

My experience with Mavic rims support this comment. I have approximately 10,000mi on a set of CXP21s that have had one minor truing, never a spoke replaced, and they look like they'll go another 10,000mi. Another set I ride are OpenPros wrapped around Ultegra hubs. Only a few thousand miles on them, but the same story. Not a single problem of any kind.

Had the same wheel set for about a year, had about 4000 miles on them. the rim started cracking around the spoke holes. Couldn't find a replacement rim to match the paired spacing of the spoke holes. The whole wheel was junk, aka not worth fixing.

But in bontragers defense, they were good while while they lasted, Never went out of true once, and I ride through some rough stuff. Can't say that for my new Openpro's and ultregra hubs. :/

i agree, cant beat Mavic! nashbar.com sometimes has good deals on mavic wheel sets.

In the few years I spent as a shop mechanic I've seen more Mavic rims fail like this than I did anything else.

To the OP: If you bought it new, from a shop, and it's only 4 months old, you can probably get it replaced under warranty. Check with the shop you got it from.

Did you buy this wheel new 4 months ago? The rim and the spokes look to be pretty beat up.

If it's a new wheel, you might have a warranty claim. If not, I'd go back to the shop that trued the wheel and ask them what's up. One possible cause is overtightening of the spoke. This tends to occur when trying to true rear wheels with paired spokes because of the uneven tension between the drive side and the non-drive side, compounded by the gaps between the spoke pairs. It's easy to overtension, and the weak link between an aluminum rim and stainless spokes is typically the rim.

BTW, although I'm a user of Mavic OP and Mavic CXP33 rims, I have had this same problem happen to an OP rim two weeks after a rebuild at the shop. Since that time I have learned to build my own wheels and haven't had a repeat.

Bob

This type of rim failure is usually due to impact and/or poor quality materials. It is unlikely that the spokes were too tight. A good rim can usually handle more tension than you or I could ever apply by tightening the spokes, the nipples would round off first.
As for Bontrager wheel, the Race Lite wheels that came on my wife's Trek 5200 had uneven spoke tension, some were very loose, when the bike was brand new out of the box.

Al

This type of rim failure is usually due to impact and/or poor quality materials. It is unlikely that the spokes were too tight. A good rim can usually handle more tension than you or I could ever apply by tightening the spokes, the nipples would round off first.
As for Bontrager wheel, the Race Lite wheels that came on my wife's Trek 5200 had uneven spoke tension, some were very loose, when the bike was brand new out of the box.

Al

I disagree. I've seen several rims fail from this mode although usually after riding for more than a few months. A poorly tensioned wheel will have high tension spots and low tension spots and wheels normally flex anyway. Aluminum will stand only so many cycles before it fails. It's not that the spokes have been tightened too tight but that they are carrying too much localized load. Eventually the rim will crack and the spokes pull out. His rim is probably worse because it doesn't have eyelets to spread out the load.

Now, if you live on a desert island, as a last resort, you can fix the wheel, just file a washer to fit in the recessed groove,inside of the rim under the rim strip, and silver solder into place. Make sure the washer is steel and the hole is smaller the the spoke nipple. File all sharp ends, insert nipple, replace rim strip, thread up spoke and bring up to tension.... But If it were me...
I would just get better rims. Araya rims are so frckin" strong it's incredible!
good luck!

Bobby Lex:
These rims came brand new with my 05 poprad I bought. The wheel might look beatup because I ride them almost everyday.


I'm going to take the bike to the shop tommorow, hopefully they will replace it under warranty, I somehow doubt it's going to happen, but you never know..

From what I've heard, Mavic MA3 rims are fail a bit too often (at least with larger riders) in this manner. "Single" eyelets in aluminum that's not very thick. "Double" eyelet construction (a.k.a. "rim sockets" that spread out the load between both walls of a double-walled rim, is a better design. The Open Pro has double eyelets, as did the MA2 and MA40. Of course, I had an MA40 start to crack as a spoke pulled the eyelet out. After 7,500 miles on the drive side of a rear wheel that may not have been tensioned properly.

The nipple looks buggered up and it seems there are fewer threads showing which does suggest over tightening, imo. Take it back and see what he can do.

I disagree. I've seen several rims fail from this mode although usually after riding for more than a few months. A poorly tensioned wheel will have high tension spots and low tension spots and wheels normally flex anyway. Aluminum will stand only so many cycles before it fails. It's not that the spokes have been tightened too tight but that they are carrying too much localized load. Eventually the rim will crack and the spokes pull out. His rim is probably worse because it doesn't have eyelets to spread out the load.

Sure, but it's the uneven tension that causes the failure, not the high tension. Actually I was quoting from Brandt's book.
Would agree about the eyelets, all of my wheels have eyelets.

Al

Well I took it to the shop and the guy there told me they had to take a picture of it and send it in to Trek. Hopefully they'll be in a good mood and replace it under warranty.

keep you posted...

This type of rim failure is usually due to impact and/or poor quality materials. It is unlikely that the spokes were too tight. A good rim can usually handle more tension than you or I could ever apply by tightening the spokes, the nipples would round off first.
As for Bontrager wheel, the Race Lite wheels that came on my wife's Trek 5200 had uneven spoke tension, some were very loose, when the bike was brand new out of the box.

Al

Al, Brandt says: "The load limit for most rims is far less than what the spokes could deliver if they were tightened to their breaking point. So in a conventional wheel, it is the rim that limits wheel strength, not the spokes."

Brandt also addresses the OP's problem: "Rims also fail from fatigue. They can develop cracks around the spoke sockets....The cracks gradually weaken the wheel by releasing spoke tension. If the spokes are retensioned to retrue the wheel, they will eventually pull out of the rim."

That's exactly what the OP stated. The wheel had recently been trued, soon afterward the spoke pulled out of the rim.

If I had to guess whether this was a defective rim or a defective wheel-build, I'd bet on the latter.

Bob

Love my Mavic Open Pros w/36 db spokes around Ultegra hubs.

Al, Brandt says: "The load limit for most rims is far less than what the spokes could deliver if they were tightened to their breaking point. So in a conventional wheel, it is the rim that limits wheel strength, not the spokes."

Brandt also addresses the OP's problem: "Rims also fail from fatigue. They can develop cracks around the spoke sockets....The cracks gradually weaken the wheel by releasing spoke tension. If the spokes are retensioned to retrue the wheel, they will eventually pull out of the rim."

That's exactly what the OP stated. The wheel had recently been trued, soon afterward the spoke pulled out of the rim.

If I had to guess whether this was a defective rim or a defective wheel-build, I'd bet on the latter.

Bob

Brandt, page 32- "Rims usually fail during crashes or from hitting road hazards such as potholes and rocks".
In the next sentence he says- "Rims also fail from fatigue".
The only point I was trying to make is that high spoke tension is usually not the cause of rim failure, and I was assuming the wheel was properly built.

Al

Brandt, page 32- "Rims usually fail during crashes or from hitting road hazards such as potholes and rocks".
In the next sentence he says- "Rims also fail from fatigue".
The only point I was trying to make is that high spoke tension is usually not the cause of rim failure, and I was assuming the wheel was properly built.

Al

But I don't think you are looking at this wheel properly. The paired spokes of a low spoke count wheel, like this one have higher localized tension than a conventional wheel. That higher localized tension will make the wheel more prone to spoke pull out than a wheel with more evenly spaced spokes.

Also, spoke tear out doesn't usually happen in crashes or from hitting road debris. Blips or cracks in the rim would be more usual but having a spoke pull out like that wouldn't be expected from that mode of failure.

Rim-damage from impacts are usually dents on the sides or permanent flat-spots. Due to the direction of the impact, it actually reduces spoke-tension in that spot. The loss of tension is then distributed to the other spokes. That's how wheels go out of true as well, the momentary flattening removes all spoke-tension in that spot and the nipples rattle loose.

The failure of the OP's rim is simply fatigue. Most likely due to the high-tension needed for low spoke-count wheels.

But I don't think you are looking at this wheel properly. The paired spokes of a low spoke count wheel, like this one have higher localized tension than a conventional wheel. That higher localized tension will make the wheel more prone to spoke pull out than a wheel with more evenly spaced spokes.

Also, spoke tear out doesn't usually happen in crashes or from hitting road debris. Blips or cracks in the rim would be more usual but having a spoke pull out like that wouldn't be expected from that mode of failure.

Not according to my tension meter. Paired spoke wheels I've checked certainly do not have higher tension than conventional wheels. In fact my wife's Bontrager Race Lite wheels were built with much lower tension than my conventional wheels.

A wheel that fails with a spoke pulling through a rim started with "blips or cracks" in the rim.

High spoke tension causing rim failures is a common misconception. High spoke tension makes a stronger wheel, as long as the tension is even around the wheel.

Al

I've heard that some anodized rims are prone to developing stress cracks at the spoke holes, even with eyelets.

Rim-damage from impacts are usually dents on the sides or permanent flat-spots. Due to the direction of the impact, it actually reduces spoke-tension in that spot. The loss of tension is then distributed to the other spokes. That's how wheels go out of true as well, the momentary flattening removes all spoke-tension in that spot and the nipples rattle loose.

The failure of the OP's rim is simply fatigue. Most likely due to the high-tension needed for low spoke-count wheels.

Metal fatigue in the rim is caused by repeated flexure from riding rough roads. High spoke tension puts the rim in compression making it stronger and more resistant to flexure. Low tension allows the rim to flex more and fatigue faster. Of course adding spoke tension to a previously fatigued rim may cause failure. I don't know what happened to the OP's rim, but it didn't fail because the original build had too much spoke tension. I agree that this failure was due to fatigue, the question is what caused the fatigue, and the impact examples in your first paragraph may be the cause of the fatigue, a combination of repeated flexure and uneven and low spoke tension.

If I had not re-tensioned and trued my wife's Bontrager wheels when they were new they might well look like the OP's wheel. I look forward to the day I replace her wheels with conventional cross-spoked wheels.

Al

Now that you guys brought it up. I remember looking at some of the other spokes around the wheel and there were two little cracks perpendicular to the spoke on some of them. When I took the wheel to to be trued it was done at the suggestion of someone who worked at the shop. He said he noticed that my spokes were loose (flexing) and suggested the tightening. Who know how long I was riding with the loose spokes...

Not according to my tension meter. Paired spoke wheels I've checked certainly do not have higher tension than conventional wheels. In fact my wife's Bontrager Race Lite wheels were built with much lower tension than my conventional wheels.

A wheel that fails with a spoke pulling through a rim started with "blips or cracks" in the rim.

High spoke tension causing rim failures is a common misconception. High spoke tension makes a stronger wheel, as long as the tension is even around the wheel.

Al

The individual spoke in a pair spoke wheel may not have a higher tension then a conventional wheel but, at the rim, where it counts, the force exerted on the rim per unit area would have to be higher than for a conventional wheel. That's why the rims on wheels like the Race Lite are heavier than conventional rims (according to Sheldon Brown). They have to be beefier to take the force.

As for high spoke tension causing rim failures, the rim will fail before the spoke will. With a soft metal like aluminum, there is a limit to how much pressure you can put on it before it will fail. I do run very tight, high tensioned spokes on all of my wheels and they are all evenly tensioned but I have seen many rims crack and fail at the spoke hole.

The individual spoke in a pair spoke wheel may not have a higher tension then a conventional wheel but, at the rim, where it counts, the force exerted on the rim per unit area would have to be higher than for a conventional wheel. That's why the rims on wheels like the Race Lite are heavier than conventional rims (according to Sheldon Brown). They have to be beefier to take the force.

As for high spoke tension causing rim failures, the rim will fail before the spoke will. With a soft metal like aluminum, there is a limit to how much pressure you can put on it before it will fail. I do run very tight, high tensioned spokes on all of my wheels and they are all evenly tensioned but I have seen many rims crack and fail at the spoke hole.

I agree they should be higher, but in the real world are they? Not in my experience.

Yes a rim may fail before a spoke, the question is why, and the answer is not from high tension at the original build.

Peace

Al

No, the original tension probably won't break the rim right away. But that continuous tension over time will fatigue the rim. Let's say you don't even ride the wheel, the spoke-tension will eventually cause that failure in the OP's picture. It may take 10,000 years, but it will pull through eventually from the force of spoke-tension.

So yeah, with repeated use and high-stress use, you'll accelerate the failure. With loading and unloading of weight, it does cycle the tension on and off. This causes fatigue failure faster than if the material is stressed at an even level all the time. The trick is to find a tension where it balances out the failure rate between initial tension vs. cycling loads.

I guess the solution to these high-tension low-spoke count wheels is to use something similar to butted-tubing. Add more material where the stress is highest. So maybe thicker metal around the spoke holes, or eyelets would be a good idea. And on bare-rims, washers are typically used on the back side. FIR rims usually comes with a backing plate for the hole.

No, the original tension probably won't break the rim right away. But that continuous tension over time will fatigue the rim. Let's say you don't even ride the wheel, the spoke-tension will eventually cause that failure in the OP's picture. It may take 10,000 years, but it will pull through eventually from the force of spoke-tension.
.

I'll report back in about 10,000 years. Meanwhile I'll keep building mine with lots of tension and eyelets.

Al

No, the original tension probably won't break the rim right away. But that continuous tension over time will fatigue the rim. Let's say you don't even ride the wheel, the spoke-tension will eventually cause that failure in the OP's picture. It may take 10,000 years, but it will pull through eventually from the force of spoke-tension.

So yeah, with repeated use and high-stress use, you'll accelerate the failure. With loading and unloading of weight, it does cycle the tension on and off. This causes fatigue failure faster than if the material is stressed at an even level all the time. The trick is to find a tension where it balances out the failure rate between initial tension vs. cycling loads.


Warning! The following comment is not relevant to everyday time scales!

Fatigue is caused by accumulated changes in the Strain of the material. While a wheel just sitting there certainly has both stress and strain, they are not changing and the material will not fatigue. There is probably some minute plasticity well below the elastic limit in metals, but it's negligible enough that they don't tell undergraduate mechanical engineers about it. Even then, the effect would apply to the spokes as well, and I would put my money on the theoretical motionless, neglected, uncorroding wheel gradually losing tension rather than failing catastrophically.