I thought you'd graduated Clock, no idea you were a 2nd year! How'd your exams go?
Cole, the forces you impose on your teeth when you clench + grind of a night is incomparably more than what you're capable of doing when conscious. I'd be surprised if the damage was solely cycling imposed. Rather, my belief is that the damage is being done of a night. A split will help in this regard, likewise a mouthguard. If you can't sleep with something in your mouth (like me), you can also get regular buildups. It's could potentially be quite pricey for a member of the public though, not sure what most dentists would charge for a situation such as yours.
To elaborate from the sports drink angle, I'd also suggest that only have 2 a week is not enough to cause significant erosion. It may well be erosion from other aspects of your diet, but I'd be very surprised if it was caused by sports drink in the quantities you've described. An easy way to tell if it is acid erosion, is to look at the affected teeth. If it is erosion, your top teeth will be in comparatively good condition, as gravity causes the drink to settle on the floor of the mouth.
But to answer your initial question, no, I've never come across anyone with a problem similar to how you describe it.