Road Cycling - Help Mavic CXP21 keep wobbling.....

My rear wheel keeps "warping." I bought my Sirrus early this year and after a month or 2 I threw a spoke. My LBS rebuilt the entire wheel. I rode it for a couple of weeks and it came out of true. The tech took the wheel back and said he put locktight (?) on it. It warp AGAIN. I took it back and he rebuilt it a few weeks ago. Then on Monday I was riding home from work and I litterally hear the creak sound as I was riding. Stopped and warp city.

I'm going back to the LBS today. Any thoughts? I weight 220. Am I too heavy for this wheel?

Thanks

Originally posted by Rats13
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I'm going back to the LBS today. Any thoughts? I weight 220. Am I too heavy for this wheel?

Thanks

No. You aren't.
Find a LBS that does better wheel work.
If they did a good job building the wheel, and properly tensioned the spokes, you wouldn't be having a problem. I'm betting, if they didn't do it correctly in the first place, that they aren't going to get it fixed properly either. That's been my experience.
I had a CXP-23 that kept going out of true. My LBS re-trued it several times, and it would go out again within a few miles. I took it to another shop and they fixed it on the first try. Never went out of true again.

I have written about this problem with CXP 21 in several threads. (Look thrm up). I had the same thing happen and I am 165 pounds. It is a function of machine building on a non-welded rim. Certain spokes loosen, then the wheel goes out of true, and if you do not correct it immediately spokes break. In my case, my rear wheel went out of radial true permanently--i.e. the rim got bent in.

My theory of why this happens is that CXP 21s are not welded where the two ends of the rim come together. They are bolted together. There is some flex in there. I believe that that contributes to the loosening of spokes. Also, machine built wheels do not have the compound in the nipples to hold the spokes in place.

After suffering for a year and half with these losers, I bought a set of CXP 33s hand built by Colorado Cyclist for about US$220. After about 9,000 miles they have not budged out of true. I hate to say it, but the answer to problems with CXP 21s is a new wheelset.

I am sure that someone will answer this message with a diatribe against CXP 33s (even through they have probably never ridden them), because the set is 5 ounces heavier than the Open Pros and because the aero profile of the rim does not add any advantage (so they say). Actually, that profile adds to the strength of the wheel. You might consider these at your weight. I ride on terrible roads and I wanted something bombproof. Actually, I am going to get Open Pros on my new bike.

Good luck,

Rich

Make sure that a shop uses spoke prep on the wheels. Any shopo worth its weight in anything will do that, and it might help you out. That might also be a good interview question for a shop you take the wheel to next. Otherwise, get yourself a truing stand and some spoke prep and do it yourself. If all else fails, and stinger's right, a new wheelset is always a way to go. Just make sure you find a good shop to build a set up for you.

stinger, with regards to CXP33's, they are bombproof, but I notice them being more sluggish when climbing. They're a solid rim, that's for sure, but so are the Open Pros. I spent thousands of miles on a set of CXP33's, and noticed a difference when I switched to Cosmos wheels, which basically use the Open Pro rim. Now that I'm on a set build with Open Pros, going back to the 33's seems to be out of my mind now. And, I'm about 185 pounds and ride on a half mile of dirt road daily, so I've done a fair amount of field testing with both rims.

Originally posted by ImprezaDrvr
stinger, with regards to CXP33's, they are bombproof, but I notice them being more sluggish when climbing. They're a solid rim, that's for sure, but so are the Open Pros.

I suspect that you are quite correct. After my experience with CXP 21s, I went for overkill. The new bike will have Open Pros, with an eye on getting wheels that help with climbing. Thanks for the advice, it confirms what I have heard from others.

Rich

Sounds to me like you have a bad set. I have a Giant with CXP 21s and have been riding it for 2 years - the wheels are true as new. I do take the bike in for regular maintenance and they always check the wheels, but I've never had even a hint of a problem (knock on wood.)

Originally posted by Stinger9oh
It is a function of machine building on a non-welded rim....My theory of why this happens is that CXP 21s are not welded where the two ends of the rim come together. They are bolted together. There is some flex in there. I believe that that contributes to the loosening of spokes. Also, machine built wheels do not have the compound in the nipples to hold the spokes in place. [/B]

The reason your wheels are going out of true is NOT the fact that the rims aren't welded. They are not bolted either - they're pinned. Many many excellent wheels are constructed this way and if built properly will stay true for years. Welded rims are a fairly recent development, and while they have advantages, there is nothing inherenly wrong with pinned rims - no "flex".

You may have hit the mark about the wheels being built by a machine. Most machine built wheels that I have seen are not tensioned enough. Spokes must be tensioned enough that they do not ever go slack (zero tension) when they are on the bottom supporting the load (your weight + the bike weight). If they go slack they will loosen and additionally they will fatigue prematurely (break) from the stress cycles. One way to fix a machine built wheel is to tension all the spokes. Any good bike mechanic can do this for you. With a properly tensioned wheel, spoke prep is not needed to prevent loosening. It is helpful, however, if you want to adjust them some time in the future.


[i]I am sure that someone will answer this message with a diatribe against CXP 33s (even through they have probably never ridden them), because the set is 5 ounces heavier than the Open Pros and because the aero profile of the rim does not add any advantage (so they say). Actually, that profile adds to the strength of the wheel. You might consider these at your weight. I ride on terrible roads and I wanted something bombproof. Actually, I am going to get Open Pros on my new bike.
[/B]

Actually the CXP-33 is an excellent rim - very strong and worth the weight penalty IMO. The Open Pros are good too, though a large percentage of them develop creaks at the spoke nipples due to the eyelets that they use. I have both on different bikes and have no problems with either. My wife has been riding a pair of wheels with CXP-21's for 7+ years and has never had a problem with them going out of true or with spokes breaking. She is not as heavy and probably not as strong as the original poster. For his situation, I suspect the damage from undertensioned spokes has already fatigued his spokes, and they will continue to break over time. I would recommend he have all the spokes replaced and properly tensioned by a wheelbuilder who knows what he is doing.