Hmmm now I have to talk to doc about it I just thought it was lung clearing I get a lot of flem when I ride it tends to be towards the beginning of my ride (especially going up hill) but it subsides before the end of the ride. After I ride I really do not have any trouble breathing though I do have a wheeze sometimes. Always chalked it up to 26+ years of smoking and all those good exhaust fumes I suck in during my commute.