The rear Avid Elixir 5 brake on my Paragon has been vibrating so much its been almost unusable since I got the bike. The vibrating makes an awful sound and removes nearly all of the braking power. Only when riding very slowly or when the rear brake is really hot does it work correctly...so hardly ever. A few riders on Mtbr who were experiencing similar issues with their Avid brakes tried adding lead weights to the calliper and seemed to have some success with the idea. So I stuck four pounds on the calliper and went out for a ride to see if the idea works. The added weights have more or less fixed the problem. Hopefully the idea can be refined a bit, firstly because I want my money back and secondly because the rear brake still vibrated once or twice during the two rides so far. If added weights don't totally fix the problem then I will try some other ideas and if all else fails, return it to my LBS.