Mine works fine. I mount it under the down tube, right in the path of front wheel spray (despite a fender and mudflap) so I bought some clear heat shrinkwrap film on EBay in 4 inch size (there is a seller who sells it in ten foot lengths), sealed the pump inside the shrinkwrap, and essentially waterproofed it. If I use it, I just peel off the shrinkwrap and then replace it after the ride.