The tight fitting mesh sleeve uses a silicone strip around the upper opening to help prevent slippage, as well as a single Velcro strap up top.
We found that the fit on our medium pads was so snug there was no need to actually use the strap to keep them in place and even after multiple crashes, they barely budged on our legs. Considering their lightweight build and severe lack of bulk, we have been constantly impressed by the protection they offer in tumbles too.
Initially, we were very impressed with pedalling comfort from the Indys, with the guards staying firmly in place and the D30 padding comfortably bending with each and every pedal stroke. It was only after we had spent a few long hot days in the saddle that we found the slightly pointed edge at the bottom of the D30 padding had rubbed both shins quite badly.
Although that was annoying, it was easily remedied by tucking the lower part of the mesh sleeve under the bottom of the padding, and so far it seems to have stopped the rubbing entirely.