Rims can be damaged by alot of things going wrong.. From wrong tension on the spokes to wrong pressure in the tire and hittting something hard.. My bike had been sitting alot(before I bought it) cause i noticed that a quarter of the spokes on both rims would just spin causeing the rim to lose tension. I imagine they rode the bike like that, thats not good. Well i was gonna change spokes and tires and noticed a really bad stress crack on the rear rim. Well now i have black excel rims and there awesome looking but to top it all off,,,,,,,,,,,,,,I know that i am SAFE and I have confidence in the rims!!