Joined: Jan 2011
Posts: 247
Likes: 0
From: South Yorkshire, England.
Bikes: Colnago CX-1 Record 11sp. Carbon Epic expert 29er, Claud Butler Dalesman. Proflex X-px Works, Cougar 653. KHS Montana Pro, Hercules Alassio. Ammoco Monte Carlo F/SS. Corratec Superbow Fun 29er. Claud Butler Midas. Kenisis T2. Peugeot Perthus.
Well imo they are necessary, they protect the valve and keep it clean, i think it's more likely to be laziness/bad practice/loss of cap.