But it might if it has a downtube that shields a standard water bottle, and you compare a P5 with water bottle to a P4 with water bottle like what CA used at the 70.3 worlds. This would actually be an important consideration to me because I like to have a frame mounted water bottle even if it is not Slowtwitch approved. Don't even get me started on Total Immersion, Powercranks, or functional strength training :-)