I'm using a beater lately due to issues with my reg bike needing major overhaul.
The beater has 26" wheels with schrader holes (my other bikes are both presta). My pumps are Joe Blow & MiniMorph.
JB's dual head is wrecked after 4-5 uses on the schrader stems; the MM wouldn't detach easily, in fact it ripped the valve right out of the innertube.
I'm thinking of emailing Topeak to find out if they can send me a replacement head for the JB but frankly right now I'ma hatin on schrader valves biggie time.