Both Presta and Dunlop valves can be converted by simply swapping the valve core. There is also an adapter for Schrader valves that screws onto the top of the existing valve – this allows you to ...

Here in Germany most bicycles use Dunlop/Woods valves. I have switched to Schrader just because it’s easier to get a decent pump for it. I don’t think I have ever noticed a Presta valve on a bike.