I was just going to post a similar topic!! I have had that amonia smell as well-- after especially long rides and lately after some of my longer runs. I too have wondered what is was, but have no answers. I'm by no means sedentary, and get the odor only after I exert myself to a fairly high degree. I just took up running a couple of weeks ago because I can't stand riding inside and have recently worked myself up to my longest run of 6 miles this weekend (which was hard, but definitely within my means as I didn't even feel sore afterward). Anyway, I definitely noticed it after the 6 miler, and even sometimes on my shorter 4 mile runs if I've put in some hard sprints along the way, or when I have upped my pace for the day. I've always gotten it on my longer (50+ mile) rides as well, and sometimes even shorter ones..I just wanted you to know that you weren't alone out there. I hope some good info comes of this discussion because I'm completely curious...I personally don't think it's anything to be concerned about as I've been getting "the smell" off and on since I took up cycling a little over 2 years ago...

Kristin