Teaching in a research based field, I am aware of the placebo affect and it is a possibility. I also know there is some research that suggests that aero helmets can reduce wind drag 13%.. I do know, I now consistently ride 2 miles an hour faster than before I had the helmet and some of that could be psychological and better fittness but the biggest part of any sport is subjective in nature. The only concrete thing we have to go by is the data and unless my computer is broke, it reads two miles and hour faster. Also, the geometry of the TT bike puts more emphasis on the gluts and hamstrings rather than more focus on the quads. The gluts are by far more powerful than the quads and coupled with a very stiff bottom bracket equals better power transfer. Probably a combo of factors made the improvement... Just was looking for some input on disc covers.. I also understand that one glove does not fit everyone. I will probably give them a try, and maybe my mind will boost what they will actually do. I will take 1.5% plus the subjective end also.