triumph.1

hi,

I am about five years into several sets of crap easton carbon clinchers and one set has finally started to delaminate around the rear brake track. Last season I had a small spot delam and warp the same rim and i trued the warp out about 90%. I rode the wheel without an issue up to the current date. I noticed after a long weekend of wisconsin hills the same rim delam has gone to a consistent line along the brake track. I don't have the wheels on at this point and won't ride them again on the road. My question is and not knowing the real answer myself is Can I likely get away with riding the wheel on gravel or flat trail where there is minimal braking? What would be the actual failure with a delaminated brake track? I am ordering up a new set of campy shamals and have enough wheels around to use, but hate the idea of tossing an expensive wheel when I used it for a year already. thanks in advance.

Sy Reene

Missing something here.. you start off saying the wheels are 5 years old, and then are worried about whether new wheels will last 1 year?

triumph.1

No, I said The wheels are 5 years old and I have used the wheel damaged for the last year. I want to know what the real risk is running the wheel on a slow moving gravel, flat trail bike as I don't want to bin it unnecessarily if I can get some more use out of it. I do not understand the make up of carbon or how it reacts to damage. I guess more than anything I am wondering if anyone has done what I am asking. I fully understand the risks but am trying to gain a bit more understanding of delamination.

FBinNY 

Odds are that you can use them on gravel until they die. There's the risk that the flanges fail and the tire blows, but I think it's probably an acceptable risk, given that it's a rear wheel.

Of course you might end up walking home, so local use only makes sense.

I use a "safety method" if/when I'm concerned about rim flange failure. I pump tires about 20% higher, as a stress test, then bleed them to riding pressure. The hope is that the rim will fail before I leave home, or if not, last until I return.

So far that's worked out OK, but I don't know if it was pure luck or science, because the one rim I was most sure was ready to fail was finished off in a crash.

TimothyH

Slow or not, braking or otherwise, gravel is not going to be easier on components than is pavement.

triumph.1

Thats info I can use. I think of all the people that I have seen on forums and discussions preach you will basically die if you use damaged carbon, but I always wonder if the truth of the matter is much much less likely to end terribly than to just have the rim break or crack at a certain point and end the ride not my life, especially given that I have ridden it in fairly risky situations w/o issue for a year. I just look at it now and realize it is probably getting to a point downhill runs and fast group riding is not an option. Thanks FBinNY I like realistic answers.

triumph.1

I know this, but does not answer my curiosity............

TimothyH

I tend to take people literally. Two questions were asked:
Sorry If I was not clear. My post was in response to the first question.

I don't think braking will have as much to do with failure as will impact forces on rougher unpaved surfaces, especially with something already compromised.


-Tim-

Dan Burkhart 

You made no mention that you are using brake pads intended for carbon rims. Regular pads for use with alloy rims will destroy carbon rims.
Just last week, a guy brought in his year old BMC complaining that his front rim was delaminating. Well yeah, lookit here. When did you put these brake pads in?
The rim was toast, he thought it should be warranty. No chance.

FBinNY 

IMO gravel biking may be the perfect use for a rim on it's last legs, either CF or aluminum.

The fact that it may be harder on the wheel is a plus, because it accelerates the process and brings it to conclusion sooner.

Product life isn't always black and white. Many items, including tires and wheels often have a "not good enough for serious use, but too good to trash" phase. You have a choice of pushing it and continuing to ride them on long rides, or putting them aside for "emergencies" and accumulating ever more of stuff in this category.

Or, like the OP, you can look for an application where they can serve, saving you from beating up prime stuff that's probably too good to be killed off this way.

By way of analogy, I always had 8 wheels for my car, 4 with snow tires, and 4 with highway tires. After 2 winters the snows would be too worn to be useful for a third winter, so I'd leave them on come spring hoping to wear them out. However, if I was planning a long trip where the performance penalty of the snows would be significant, I'd switch to the better tires, then switch back for local driving. The objective was to get as many miles out of my dead snows before November, when I'd have to toss them and mount 4 new snows.

Likewise with the OP, using the dying CF wheels on gravel, gets him value (in sparing better wheels) as long as they last, and when it's time he can discard them and make room for something new. OTOH - if he's planning a longer gravel ride, he can switch to a more reliable pair of wheels, then switch back later.

BITD (wa-a-a-a-a-y back) before cyclocross came into it's own, we used to save all kinds of dubious stuff - bent forks, warped wheels, cut and booted tires, and god knows what other "gee, maybe I'll find a use for this" junk we'd put aside during the season and race cyclocross in the Fall giving our favorite stuff a chance for death with dignity. Currently, I don' own a gravel bike, but if there were gravel roads near here I know exactly what I'd build one out of.