Unless your ride is not strenuous you will also get what we (my teammates and I) refer to as TT butt..... it may spare your hamstrings, but the point at which your hamstring (I think - but I'm not a PT or a physiologist, so correct me if it is a different muscle) attaches to your backside gets *sore*. Bent over tends to mean more pressure on your pelvis and soft tissues too, so finding a good TT saddle can be a challenge.