I'm wondering how do you stop your dowtube/seattube mounted bottles getting covered covered in crap? Specifically the bit you plan on sticking in ones cakehole. As the odd time I have used bottle mounts on my old SS bike I always found this an issue. Mud is not an issue, but dog pops etc, is.
...or should I just use a hydration pack?
Just to clarify, I'm not talking racing, more all day on/off road rides.