Bike Tubes

Also known as innertubes, bike tubes are the rubber liners that fill and hold air inside your tire. Clincher  tires have a space for the tube between the rim and the tire, and tubes are easy to swap in and out. Tubulars,  or sew-ups, have tubes already encased within the tire. The two most important aspects of bike tubes are valve stem and tube materials.

Types of Tube Stems
Shraeder Valve (image from Biketiresdirect.com)	Presta Valve Stem (image from Biketiresdirect.com)
Shraeder valves are the same type you'll find on car tires Thick, wide and sturdy valve. Can take standard pump end. Can withstand a fair amount of abuse and get knocked around without tearing Often found on lower-end bikes.	Presta valves are more popular for bicycles and they're also lighter and more aerodynamic. Narrower profile that's advantageous with skinnier rims, and a screw-down lock to prevent air loss. More fragile than Shraeder valves. Presta valves come in a number of lengths, which will depend on the type of rim you have. Most standard 700 size rims are fine with 32mm stem, while aero rims or deep dish users will want a longer stem. If your pump only has a Shraeder end, you can buy an adapter  to fit it.

Tubes are typically made out of butyl rubber, which is inexpensive (about $4-$11) and maintains air pressure well. Standard road tubes (700x23c) usually weigh about 95 grams, with lighter tubes like the Michelin Aircomp  and Kenda Superlight  weigh in around 75-85 grams. They use less material but they're also made a little more even than less expensive tubes. Unless you're a racer or serious biker, standard road tubes will do fine.

The other tube material is latex. It's the most expensive material, but is more elastic than butyl, which results in less rolling resistance (rolling resistance is measured in terms of heat loss and tire/tube deformation as the tire rotates) and a more efficient ride. They are also lighter, more resistant to puncture and pinch flats, but don't hold air pressure as well as butyl. Latex  tubes will cost you about $20-$25.

There's a fair amount of elasticity in both tubes, so they usually come in a range of sizes like 700x18-23c. It's not terribly important to find the exact size tube for your tire. They'll still work well. Sometimes riders who want a thicker tube (thinking it will prevent some flats and be more puncture resistant) will use a tube that's a little bigger than their wheel size.

Tire Sealants

Although it's normal for all tubes to lose air over time (known as "air-porosity"), you may want to use a sealant as an extra precautionary measure. Tire sealants  are a liquid compound you put inside a tire tube that seals tiny holes and punctures almost instantly. When you get a hole, the high pressure air inside the tube pushes the sealant through the hole at high speed. When the sealant meets lower pressure air (ie. outside air), it coagulates and forms a seal. It's pretty effective. Slime  brand sealant is made for standard butyl tubes, but can't be inserted in tubes with Presta valves. You can, however, buy tubes with Slime pre-inserted or cut small piece out of your tube, apply the sealant that way and patch up the hole afterward.

Back to bike tires buyer's guide

External Links

Bike Pro - Very detailed overview of bike tubes.