It is possible to do a track stand on a freewheel-equipped bicycle it the front wheel is pointed up a sloping section of road.

The traction of a tire is affected by:

• The composition of the rubber of the tire
  Softer rubber gives better traction, but wears out sooner.
• The nature of the road or other surface
  Paved or unpaved, wet or dry, hard or soft, smooth or bumpy.
• The tire pressure
  
  • If the tire is too soft, it can "sqirm" and deform itself so that it will not track properly when making turns.
  • If the tire is too hard, it will bounce excessively on rough surfaces, bounding from bump to bump, spending too much time airborne.
• The shape and depth of the tire tread
  This is mainly a concern in the case of tires for off-road use, where a knobby tire can get a bite of a soft or irregular surface.
  For pavement riding, smooth tires get as good traction as those with tread, sometimes better. Aggressive knobby tread tires corner very poorly on pavement, because the tall knobs bend sideways under stress.

Joshua Putnam has a good discussion of trail and Bicycle Steering Geometry in general on his Web site.

See the Brake Lever Types entry for more details on this issue.

The cable from the lever normally goes around the small step of the pulley first, then through a hole onto the large step. This causes the cable leaving the Travel Agent to be pulled twice as far (but half as hard) as where it enters. It can also be used in the opposite direction if desired. (Q.B.P. Photo)

Another way of looking at it is that a trekking bike (or a hybrid for that matter) is basically a touring bike with upright handlebars instead of drops.

Although the word "trek" is of Afrikaans origin, meaning a long painful journey on foot or by oxcart, I believe the term "trekking" bike originated in Germany in the 1980s.

Trials are sometimes done on more-or-less standard mountain bikes, but more often with purpose-built trials bikes.

A trials bike is a one speed, geared very low, with a tiny chainwheel both for low gearing and improved clearance. Tires are usually fat 20" or 24" size, with agressive tread. Frames are small, equipped with a very low saddle. Trials riders never actually sit on the saddle, but a saddle is required as a safety measure.

The major technique involves locking the wheels up with the brakes, and bouncing the bike up and donwn in the manner of a pogo stick.

The cycling section of a triathlon is run as if it were a time trial. Drafting is forbidden, so there can be no team tactics or other assistance between contestants.

The popularity of triathlons has brought many new participants to cycling, and because these participants are highly motivated but not in touch with many of the hidebound traditions of cycle racing, triathletes have introduced many fresh designs to cycling, most notably the æro handlebar.

Because of the lack of team tactics, and the tendency to use fairly flat courses for the cycling leg of triathlons, all sorts of ærodynamic parts and accessories have become popular among triathletes. This is helped by the fact that triathlons are not governed by the U.C.I. and there are very few restrictions on allowable equipment.

Some indexed front shift controls provide a "trim" function, usually an extra click or two, to let the rider compensate for this.

In the early 1980s, Sun Tour used to make a special shift lever that automatically adjusted the position of the front lever as the rear was shifted, to automate the trimming process. This system turned out to be very troublesome, and was abandoned after a single season.

Modern front derailers are designed around specific chainwheel combinations so that trimming is un-necessary in most cases if the front derailer is properly adjusted. (See my article on Derailer Adjustment.)

This term is sometimes used incorrectly to refer to a triplet, a 3-place tandem.

This term may apply to frame tubing or to spokes.

A wheel which is "out of true" vertically will be out of round, and will give a bumpy ride even on a smooth road.

A wheel which is "out of true" horizontally may rub on the brake shoes at part of its revolution, causing excessive drag...or causing the brake to be adjusted looser than it should be to prevent this drag.

"Truing" is the act of making a wheel run true. This procedure is described in my Wheelbuilding Article.

The purpose of the tube is to make the tire airtight. The tire itself may have small holes and pores without creating a problem, as long as the tube doesn't leak. If the tire has a large hole or cut, the stretchy rubber tube can bulge through and burst. The tube does not, in itself, have the ability to withstand the high pressures used in bicycle tires without the support of a tire around it.

Most tubes are made of synthetic (butyl) rubber.

The oldest material for this is steel of one sort or another. See also chrome-moly, gas pipe, high tension

Some noted brands/models of steel tubing for bicycle use include: Reynolds 531, 753, 853 (England), Vitus (France), Columbus (Italy) Ishiwata and Tange (Japan) and TrueTemper (U.S.A.)

Steel bicycles are built by joining the tubes either with lugs, welding, or fillet brazing.

Tubulars use Presta valves.

Most people find expensive tubulars too expensive for recreational riding...but cheap tubulars are distinctly inferior to good clinchers, particularly in that they tend to be lumpy and crooked.

Comparing high-quality tubulars with clinchers, including the rims, tubes, etc, tubulars save about 50 grams per wheel...but your bike winds up heavier, because you really need to carry a complete spare tubular, as opposed to a tube and/or a patch kit. This doesn't apply if the team car is carrying spare wheels/bikes for you.

If you don't glue your tubulars on properly, they can roll off, causing you to crash. If you get a flat on the road, you can't glue your spare securely, since the glue needs to dry overnight; as a result, you have to ride very gingerly on your spare, taking it really easy on the curves and descents. If you get two flats on the same ride, you're screwed.

Some people believe that tubulars corner better in the rain...but I never go fast on wet roads anyway. If you flat in the rain with tubulars, your ride is over, because there's no way to make a wet tubular stick to a wet rim.

Tubulars are fairly immune to "snake-bite" rim cuts, and may offer slightly better "suspension" action than comparable clinchers. Their rolling resistance is actually worse than good clinchers in most cases, due to flex of the glued section.

Standard size tubular tires use a rim that corresponds in diameter to a 622 mm (700C) clincher rim.

Back in the 1970s, 622 mm clinchers were very rare in the U.S., and most sporty bikes used either 630 mm (27 inch) clinchers, or standard (622 mm) tubulars.

The fact that these sizes are so close led to an in-accurate habit of referring to "27 inch" tubulars. This careless nomenclature still causes confusion, and people often imagine that there is a different "27 inch" size in tubulars as there is in clinchers.

This is not true. THERE IS ACTUALLY NO SUCH THING AS A "27 INCH" TUBULAR.

All full-size tubulars fit all full-size tubular rims.

There are smaller size tubulars, "26 inch", "24 inch" and even smaller, but those are VERY uncommon, mainly used for children's race bikes, which hardly exist at all in the U.S.

There are several articles about tubulars in Jobst Brandt's FAQ section:

• Folding a Tubular Tire
• Making a Tubular Tire
• Mounting Tubular Tires
• Rolling Resistance of Tubular Tires

This size is probably a good option for taller riders for off-road use, compared with 559 mm (26 inch decimal) wheels. Larger diameter wheels don't sink as far into holes so they will give a better ride in rough conditions.

For shorter riders, wheels this large will cause unfortunate compromises in frame geometry, so they're probably not a good option for riders of short or medium height.

Most crank sets are three-piece, there are also one-piece crank sets.

Shimano revived the two-piece design with the 2004 Dura-Ace "Hollowtech II ® " crank and bottom bracket. These use external-bearing bottom brackets and large-diameter hollow shafts.

This system has "trickled down" the Shimano line in later years, and is gradually replacing three-piece cranks on most better quality bikes. Other manufacturers have also adopted this system, which seems to be becoming the new de facto standard.