This probably is not going to help much, but you are not alone in these symptoms. I've watched many a racer go really hard and feel nauseous afterwards. I'm not sure what the medical or physiological causes are, but suffice it to say it is a pretty normal occurrence.

It usually happens when that person is going harder than normal or under more stress than normal. When I was on a mountain bike team in California years ago, it seems like every time we would go to Mammoth, there would be at least 1/2 of our team sick after or during the races. But, of course, they were going as hard as they could at altitude and this would contribute to the nauseous feelings.

Don't really know what to do about these feelings. As you get fitter, it probably takes longer or harder rides to get to this point where physiology is protesting. So all I can tell you is as you get fitter, this will probably happen less and less, but I'm not sure how you stop it.

spoke