Originally Posted by Velo Mule

+1 for Salamandrine response. In front of the seat tube was the most common. The Silica Impero was meant to fit there as well as a Zefal with an umbrella clip. I had a Zeus (I still have it) that is also shaped like the Silica and fits in front of the seat tube. To me, I still like this position and prefer not to mount the second water bottle if I have a full size pump.

Back then on my Astra, I had a Zefal pump that I as able to fit behind the seat tube. I thought this was a pretty nifty place for it since it fit. Not too many frames allow the pump to fit behind the seat tube, and you need a pump that has an umbrella clip as well.

What pump do you have?