2 problems... 1: Bontrager Corvair rim: The LBS tells me this rim is "concave" - WTF is this, and what's wrong with it if it is as he says "concave"?... 2: Bontrager Corvair A-Sym rim: The rim is losing shards of metal everyday, very fast, very big, very badly. It is affecting my braking. The LBS gave me new blocks to try, and I told him to #[email protected]% off. Any ideas what is casuing this? My rims are always kept clean. BTW, the A-Sym is only 1.5 monthys old, and I didn't have this problem with the old A-Sym before it.