Concept2 Forum

I bought a pair of the water bottle mounts from Concept2 and was never satisfied with them. No matter how much I tightened the thumbscrews (even using a pliers), the cages would rotate down on the handlebars. I ended up removing the handlebar mounts and just used a pair of 2-1/2" long screws to straddle the top and bottom of thehandle bar stem and now they are perfect.

I bought a cheap pair of bottle carriers in an end of line store for €0.99 in France and fastened one to the same place using two long snap-ties which does the trick.
Cheap and cheerful