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303 braking problem(10 posts)

303 braking problemDougSloan
Aug 26, 2002 6:17 AM
I have a set of Zipp 303 carbon clinchers. The braking in the rear is extremely bad. The brake will lock the tire very easily, and before lock-up it is so grabby it about throws me off the bike, and I can feel, and even see, pulsing in the brake lever.

This is on the Colnago with Record brakes, dual pivot in rear. The pads are fine. With either Ksyriums or Nucleons, there is no braking problem at all.

The wheel appears to be slightly out of true. I had it re-trued by the local shop, which made it better for a while, but again the braking is so bad that it is dangerous. The out of trueness does not appear to be bad enough to cause braking problems, but I can't think of what else it could be. I've cleaned and clean the brake surface, but this doesn't help.

Is there a chance that the aluminum rim section is bulging out, causing the grabbing, instead of trueness being the problem? I suppose I could mike it. Any idea what is an acceptable width range?

Is it time to send it in for warranty? I bought the set in February through Chicagoland (cbike.com). Anyone else experience a similar problem? These wheels are far too expensive to be acting like this. Thanks.

Doug
For what you paid get them fixedspookyload
Aug 26, 2002 6:28 AM
Zipp is very good with their warranty work. If you have backup wheels, I would send them back and get them right. I have ridden 303's and have never had a problem with them being grabby.
303 clincher defectBipedZed
Aug 26, 2002 6:37 AM
There was a post on the VeloNews forum about a month back dealing with this issue. Basically the 303 clinchers are prone to deforming on the aluminum braking surface. Most resolutions have involved sending the wheel back to Zipp for replacement. In many instances the problem reappears after several hundred miles. You'll need to contact Zipp directly to find out what they can do for you.

IMO, the clincher rims were always a sales concession to meet the demands of users who didn't want tubular rims.
Send them back (nm)Royle Wheels
Aug 26, 2002 8:22 AM
what pads are you using? (nm)ColnagoFE
Aug 26, 2002 9:32 AM
Record; note these are the aluminum/carbon rims nmDougSloan
Aug 26, 2002 9:37 AM
Are the pads adjusted properly?.Dave Hickey
Aug 26, 2002 9:54 AM
Are they only grabbing the aluminum? If the wheel is out of true, is it possible part of the pad is grabbing carbon instead of aluminum?
i assumed they were the all-carbon...sorry! nmColnagoFE
Aug 26, 2002 12:13 PM
re: 303 braking problemmaxxx
Aug 27, 2002 7:45 PM
Hi Doug,

I also have a pair of 303's and so far they are perfection. From your note, it sounds to me you have two different problems. Firstly, I think the 303's being grabby sounds more like a chain lube spatter on the rim and then turning waxy under braking heat/pressure. If this varys with wheels, perhaps some are "wetter" than the others. This happened to me long ago before I went to dry lubes (granted, this did not happen with my Zipp's but other rims).

Secondly, your rear wheel is definitely out of true. Carb wheels are basically set once the resin drys...period. "Re-truing" even to a flat surface puts them under uneven stress so they will never hold it and settle in like conventional alloy rims. Don't waste money and sweat on more (major) truing, only a new wheel, one that was true (or with only very minor deflection) at annealing will work for you.

I think you unfortunately lucked out and got that 1% manufacture defect... Don't give-up on the Zipp's! For me, they turned out to be the closest thing to the perfect wheel yet.

Cheers...
re: 303 braking problemjwhitcombe
Aug 28, 2002 7:56 PM
I've had my 303's for about 1 month, same exact problem except with the front. Mic'd the rim and found a bulge just above the valve stem exit. On reasonably cursory inspection, found the carbon has cracked up the valve stem area, up to the aluminum rim. Examining the rear showed the same defect. My LBS called Zipp, they are making me pay freight, wouldn't send call tag, and will get back to me sometime after they get them. Out of wheels for weeks, after paying about $1000. I would check the wheels for cracks, but try to get a shop that has enough clout for Zipp to want to provide some customer service.