How to select a tube? Hi I got a used bike and my experience with bikes is very limited. The tires and tubes are all broken so I need to get new ones. I found these tires: http://www.fahrrad.de/continental-speed-king-set-26-zoll-draht-362100.html

and I found these tubes for the tires: http://www.fahrrad.de/fahrradteile/reifen-schlaeuche/rcp-fahrradschlauch-26-zoll-universal/285443.html?eqrecqid=be78e9d1-f097-11e3-804f-c8600056a33a

but when I select the tubes the website asks me for the kind of valves I need. How to select that? Should I select the valves according to a criteria or should I get any valves?
Some rims have a small-diameter drilling for presta valves, so a schraeder (car-type) valve won't fit.

If your rim is drilled for schraeder valves, you can use presta valves, but you should use a plastic adapter sleeve to hold the valve in position and avoid wear to the valve stem or the edge of the drilling.