I'm not sure if the MB Dx has a "Smarthead", which adapts to both a Presta valvle (long and skinny) and a Schraeder valve (short and cylindical, like a valve on a car tire). Depending on what kind of tires you use, you may have to switch the little mechanism inside the pump head.

Or maybe you just don't like it.

Quote Originally Posted by kaian
A while ago, I purchased a "mini" bike pump to mount on my road bike in case of flats. I think it's the Topeak Master Blaster DX. The other day I tried using it to put some air in my tires (just to see how it worked). I could not get air into the tires! Now, I consider myself strong and in shape and I couldn't believe this! So...I'm considering getting something else. I have considered a CO2 system, but am not sure. Any recommendations? Something small and mountable would be good and something with a guage would be great, too. Thanks!