We once got a bike in at the coop that looked like it had the same tape for many years on it's aero bars. Unwrapping the bars (to replace them) resulted in a huge amount of white "powder" coming off of the bar. The ONLY thing I can think of that it'd be was sweat that has soaked into the tape and crystallized. I wasn't going to taste it to figure it out. It was... gross. The bars are still gross, the salt (I'm assuming) caused a ton of corrosion on the aluminum. The bars have been sitting by the sink for months because I refuse to do anything with them.