Need a valve extender for your racing wheels? Well, the best damn valve extenders period are made by Tufo. There are two reasons these are the best extenders. First and foremost, they simply lengthen the valve stem by moving the valve core from the tube/tire and replacing it at the end of the extension. This is a far superior design to the other type valve extender which screws on over an open and inexcessible valve core. By moving the valve core to the end of the extender, you can open the valve when adding air and keep it closed while riding. Some valves that remain open while riding can leak air during a ride as a result of vibration. This can be a real problem during a race if your valve core is obscured by your wheel and extender because you won't be able to solve the problem.
Another problem with inexcessible valve cores is that you can't deflate the tires without removing the extender. Sometimes it is very difficult to add air to a tire that's still at high pressure (from the last race) without first reducing the air pressure. If you can't access the valve core to reduce the air pressure and you can't add air, then you may be forced to either race on training wheels, race with insufficient air in the tires or breakdown your racing wheels the morning of a race. The latter would be a serious problem if your racing wheels are tubulars. All of this can be avoided by using Tufo valve extenders. Please note, though, that you must use either tubes or tires with removal valve cores. The valve cores are easily removable with either needle nose pliers or Tufo's own valve core removal tool.
The second reason Tufo valve extenders are the best is they are made from hyper-light thin walled aluminum. The lighter the extender the less out of round feeling or hop in your wheels (especially felt when coasting at high speed) is caused by the increase in weight at the rim resulting from the valve and extender. The lighter your wheels are the more of an issue this is. If you've spent the money to have hyper-light tubular racing wheels, please don't use the extenders that come with them (I'm specifically referring to Zipp extenders) since they are heavy and obscure the valve core. Instead, spend an extra $20 to get the best damn valve extenders made.
Tufo Valve Extender
This extension adds 20/28/40mm to Tufo valve stems (32mm). Unlike a normal extension that slides over the valve, these extensions are placed between the valve stem and the valve core. Simply take the valve core out of the valve stem, thread the extension into it, and then thread the valve core into the extension. There is even a rubber seal on the extension so no air can leak.
The valve core can be removed by carefully using a pair of needle nose pliers, but it's easiest and safest to use the Tufo valve tool.