Why I ride tubular tires, Part 1

All tires have tube, right? So why are some tires called tubulars and others clinchers? What is the advantage one has over another? Why should I care either way?

First a little lesson on the differences between tubular tires and clinchers. I will start with clinchers since most people are riding those and that is what the majority of bikes come with.

A clincher tire consists of an outer tire with a U-shaped cross section, and a separate inner tube. The edges of the tire ‘hook’ over the edges of the rim, and air pressure holds everything in place. There are three main components that make up a tire:

• Bead
  The “bead” is the edge of the tire. On most tires, the beads consist of hoops of strong steel wire. The beads are what holds the tire onto the rim, and are, in a sense, the “backbones” of a tire. While most beads are steel, “folding” tires use Kevlar® cord instead. Since Kevlar® is much more flexible than steel, tires with Kevlar® beads can be folded up compactly, which is convenient for touring or other applications where it may be advisable to carry a spare tire.
  
• Carcass
  Cloth fabric is woven and formed around the two beads to form the body of the tire. The vast majority of tires use nylon cord, though some use other polyamides. Up until the 1960s, cotton/canvas was commonly used. Cotton and silk are still used for some tubulars. The fabric threads don’t interweave with crossing threads as with normal cloth, but are arranged in layers or “plies” of parallel threads.

  The density of the carcass fabric is expressed in EPI or TPI (Ends Per Inch, Threads Per Inch). Generally, tires with denser fabric are more resistant to punctures and roll better. Yet the ultra-fine TPI carcass is more susceptible because the individual filaments are very fine.
  

• Rubber
  Once the fabric has been woven between the beads, and the tire has its basic shape, it is coated with rubber. The rubber is mainly there to protect the fabric from damage, and has no structural importance. The rubber that comes into contact with the ground is called the “tread.” This area usually has thicker rubber than the “sidewalls” of the tire, mainly for wear resistance. Most tires have some sort of 3-dimensional pattern molded into the tread.

  The rubber compound of a tire is composed of several components:

• Natural and synthetic rubber
• Fillers, e.g. carbon black, chalk, silica
• Softeners, e.g. oils and greases
• Anti-ageing agents (aromatic amines)
• Vulcanizing aids, e.g. sulphur
• Vulcanization accelerators; e.g. zinc oxide
• Pigments and dyes

Depending on the compound, the composition is roughly 40 - 60 % rubber, 15 - 30 % fillers, with the other components accounting for the rest.

Tubular tires, also known as “sew-ups” differ from clinchers in that they don’t have beads. Instead, the two edges of the tire are sewn together around the inner tube. Tubulars are used on special rims, and are held on to the rims by air pressure and glue. Tubulars used to be fairly common on high-performance bicycles, but these days they are an endangered species.

• Bead
  Since there is no “bead” on a tubular tire they can be a bit lighter than comparable clinchers. The development of Kevlar® beads has considerably reduced this advantage.
• Carcass
  The carcass of the tire is generally the same as described above. In many cases the fabric is woven with more and/or thinner thread allowing for a more supple ride than a comparable clincher tire.
• Rubber
  The tread is created identically to the clincher tires.

End of Part 1.