The differences between Schrader and Presta inner-tube valves

If you always inflate your bike tires at a gas station and have your local bike shop fix your flat tires, you needn’t worry about whether the inner tubes in your tires have Schrader or Presta valves. However, if you want to buy replacement tubes so you can fix your own flats or buy a pump so you can inflate your tires at home or during a ride, the differences are important.

Schrader valves

A Schrader valve, the kind of valve on car tires, looks like this with the valve cap on (yes, the cap is cracked, which is why I don’t like hard-plastic caps):

and like this with the valve cap off:

If your tubes have Schrader valves, you can check tire pressure by using a standard pencil gauge (other types of gauges compatible with Schrader valves are also available):

Note that the diameter of a Schrader valve is a greater (8 mm) than the diameter of a Presta valve (6 mm). The hole where the valve stem goes through the rim of your wheel is drilled to fit either Schrader or Presta valves. If your rims are drilled for Presta valves, you can’t use a tube that has a Schrader valve because the valve won’t fit through the hole. You may be able to have your wheels redrilled with the larger holes, but it’s not a good idea; Presta valves are commonly used with narrow wheels that would be significantly weakened by larger valve holes.

Presta valves

A Presta valve looks like this with the valve cap on:

and like this with the valve cap off:

Presta valves have an additional nut to deal with after you’ve taken off the valve cap. Here’s how the valve looks with this extra little nut unscrewed (but still attached—it can’t be removed):

If your tubes have Presta valves, you need a special pressure gauge made just for Presta valves. Mine looks like this:

Note the button on top of the brass tube. You can use this button if you need to let some air out of the inner tube while you’re holding the gauge on the valve.

With Presta valves, you also need either a bike pump that fits Presta valves or a pair of adapters that convert Presta valves to Schrader valves. If you go the adapter route:

• You’ll be able to inflate your tires at a gas station.
• You’ll want to get one for each wheel because the adapter screws onto the valve. Having to move it from one wheel to the other every time you want to check your air pressure or inflate your tires would be a bit of a bother. Happily, they’re only a few dollars each.
• Presta valves are only used on bike inner tubes, so you’ll have to get the adapters from a bike shop. If your local bike shop caters to racers, you may have to put up with some attitude from a sales person who thinks that Schrader valves are for Luddites. Don’t take any lip.