||08-12-07 05:40 PM
Just about any 700 tube will work. We have 10 bikes in the family, with tires from 26x1.25 to 26x2.4 and 700x23 to 700x41. For at least 10 years, I've bought just two sizes of tubes: 26x1.5 and 700x25. No problems ever--they're small enough to go into the skinny tires and stretch to fill the biggest ones.
I'd ditch the Schrader valves, though. They're just a pain to inflate with a hand pump. You also won't have any problems with presta valves in a rim drilled for Schrader--the hole's a little too big, but it won't hurt anything. You don't need the little grommet you may hear about to fill the hole, and I've never had any trouble from throwing away the nut that screws down on a presta valve. Air pressure holds the valve centered in the hole.