WikiPedalia is not endorsed or affiliated with the Wikimedia Foundation.

Sheldon Brown's Bicycle Glossary/T

From WikiPedalia

 

A · B · C · D · E-F · G · H · I-L · M · N-O · P-Q · R · S · T · U-Z

Spoke divider

T.A.

Highly regarded French maker of bicycle parts. Best known for crank sets. T.A. was the pioneer in triple-chainwheel crank sets. T.A. also makes bottle cages and special orthopedic pedals for cyclists with legs of different lengths.

Taco

To collapse a wheel so that it assumes a saddle shape. A tacoed wheel is more than just out of true, it has collapsed so the spokes have assumed a new equilibrium position and lost tension. Two spots, 180 degrees apart will be way off to the left; two other spots, halfway between, will be way off to the right. A taco wheel is also known as a "potato chip" wheel, depending on the local food culture. Often, the rim is only flexed, not bent, and the wheel can be sprung back nearly to its original shape.

Tadpole

A tricycle with two wheels in front, one behind.

Tandem

A bicycle or other vehicle which accommodates two or more riders, one in front of the other. Tandems for three riders are called "triplets", for four: "quadruplets" or "quads", etc.

This site contains several different articles about tandem bicycles.

Tange

Noted manufacturer of frame tubing and headsets.

Tap

A tap is a tool for cutting internal threads. It takes the form of a bolt with flutes cut in the threads, and usually has a taper at the end that is intended to start the thread. There are only a few standard sizes used on bicycles:

Tap

Size Application Metric drill SAE drill
3 mm Adjusters in rear dropouts
5 mm x .8 mm Bottle cage mounts, fender eyelets, shift lever bosses. 4.20
  1. 19
6 mm x 1mm Cantilever bosses, some fender eyelets 5 mm
  1. 9
10 mm x 1mm Derailer hangers 9.0 mm "T"
1/2" x 20 L & R Pedal threads for one-piece cranks
9/16" x 20 L & R Pedal threads for three-piece cranks
1.375 x 24 tpi L & R British/I.S.O. bottom brackets
35 x 1mm L & R French & Swiss bottom brackets
36 x 1mm Italian bottom brackets

The corresponding nut-like tool for cutting external threads is called a die.

My Tool Tips series features an article on the use of taps.

Major Taylor

50 years before Jackie Robinson joined the Brooklyn Dodgers, when bicycle racing was the most popular sport in the world, Marshall "Major" Taylor competed at the highest level, setting numerous world records and winning a world championship in 1899 -- with quiet dignity and in the face of extreme hostility and prejudice, even threats against his life. His example lends a higher meaning to the expression "sports hero". There is a fiction-based-on-fact story about him on this site. You may read more about him on the Web site of the Major Taylor Association.

Technomic ®

A series of handlebar stems made by Nitto. Technomic stems are very high-quality aluminum stems, in the traditional "7" shape popular for road bicycles. The special feature of the Technomic stem is that the vertical part of the stem is taller than usual. This is a great aid for fitting bicycles to riders who need a higher handlebar position than would otherwise be possible with a particular frame.

Tensiometer

Tensiometer
Tensiometer

An instrument for measuring spoke tension. See my article on wheelbuilding...

Tension Pulley

The lower pulley on a rear derailer. So called because its main function is to adjust the tension on the chain as different-sized sprockets are selected.

Terry ®

A line of bicycles designed specifically to meet the fitting needs of smaller women. Terry also makes and sells women's bicycle clothing, and saddles for men as well as women.

3rd hand

A clamping tool to hold the brake shoes tight against the rim, to make brake cable adjustments easier.

Threaded Driver

Older Sturmey-Archer hubs used threaded sprockets, similar to track sprockets, which screwed onto a threaded driver. Sometime in the 1940's, three-splined sprockets and drivers were introduced, which made it much easier to interchange sprockets.

Threaded driver
Threaded driver

To remove the sprocket from a threaded driver, the driver must be removed from the hub (otherwise it will just freewheel as you turn it counterclockwise.) As shown in the photo, one good way to secure it is to set it so that the legs are straddling a suitable steel bar, held in a vise. I use a pair of headset wrenches side-by-side, then unscrew the sprocket with a chain whip.

Threaded drivers are fairly rare, and are often sought after because they have the same thread as a standard freewheel hub. This makes it possible to create a hybrid gearing system by screwing a normal freewheel onto the driver. More details on this may be found in my article on my O.T.B. 63-speed bicycle.

Threaded Headset

Traditional style headset whose upper race and locknut screw onto a threaded fork steerer.

Threading Systems

For normal, generic nuts and bolts, there are two threading systems in common use, S.A.E. (U.S.Standard) and Metric (I.S.O.). S.A.E. threads are designated by a diameter and a number of threads per inch (TPI). For example, the common 1/4 - 20 means a bolt 1/4 inch in diameter, with 20 threads per inch. Metric bolts are sized by the diameter and the distance between adjacent threads, for example 6 x 1 refers to a bolt 6 mm in diameter with threads 1 mm apart. (This is the size used for brake mounting bolts and brake shoe hardware.) Similarly, 5 x .8 means a bolt 5 mm in diameter, with threads .8 mm apart. (This size is used for fender and bottle-cage fittings, shift lever bosses, and most cable anchor bolts.) A third system, known as Whitworth, was used in Britain up until the 1960's when the U.K. converted to metric.

Bicycle parts come in even more different thread systems than common nuts and bolts. There are different standards for headsets and bottom brackets for American/BMX/OPC, British, French, Italian, Raleigh and Swiss bicycles.

The table below is for threaded bottom-brackets. For the Ashtabula OPC and other unthreaded bottom brackets, see the unthreaded bottom-bracket cribsheet.

Bottom Bracket Threading

Standard: Threading Adjustable
(left) cup/cone
direction 		Fixed
(right) cup/cone
direction 		Shell
Width 		Applications/Notes
British
I.S.O. 		1.370" X 24 tpi
1.375" X 24 tpi 		right left Standard 68 mm
O.S. 73 mm 		The overwhelming majority of bicycles in current production. British and I.S.O. are interchangeable.
Shimano Hollowtech II, FSA MegaExo, RaceFace X-type ISO right left 90 mm, 95 mm including cups External cups for cartridge bearings fit British/ISO threaded bottom brackets or unthreaded shell. 24 mm spindle, spacer to use 6805 bearings with 25mm I.D.. Bottom bracket shell must be faced so cups are parallel.
Campagnolo Ultra-torque Italian or ISO Spindle diameter 25mm.
Chater Lea 1.450 x 26 TPI right left Obsolete British size but available from Phil Wood & Co.
French 35 mm X 1mm (25.4 tpi) right right
(wrong!) 		68 mm Obsolete, used on older French bicycles.
Prone to problems due to the right-threaded fixed cup, which tends to unscrew itself in use.
ISIS Overdrive I 48 x 1.5 mm right left 68mm
100 mm
ISIS Overdrive II 48 x 1.5 mm right left 68mm
100 mm 		New proposed standard oversized system.
Italian 36 mm X 24 tpi right right
(wrong!) 		70 mm Italian and some high-end French bicycles. Prone to problems due to the right-threaded fixed cup, which tends to unscrew itself in use.
Phil Wood American Isis (comments) 50 mm right left 1.5 mm thread pitch.
Raleigh 1 3/8" X 26 tpi right left 71 mm
76 mm 		Older British-made Raleighs, 3 speeds and others from the Nottingham factory.
Swiss 35 mm X 1mm (25.4 tpi) right left 68 mm Same thread as French, but fixed cup is left- threaded for reliability.

What happens if you try to mix different sizes:

Bottom Bracket
Shell Threading
(Below) 		BritishI.S.O.
1.37/1.375" x 24 tpi CUPS R-L
(34.8/34.9 x 1.06 mm) 		Italian
36 mm X 24 tpi CUPS R-R
(1.417" x 1.06 mm) 		French
35 mm X 1mm CUPS R-R
(1.378 x 25.4 tpi) 		Swiss
35 mm X 1mm CUPS R-L
(1.378 x 25.4 tpi) 		Raleigh
1 3/8" X 26 tpi
CUPS R-L
(34.9 x 1.06 mm)
British/I.S.O.
1.37/1.375" x 24 tpi
(34.8/34.9 x 1.06 mm) 		Made to Fit 36 mm Cup diameter is too large, thread won't even start. Cup diameter is slightly too large, usually won't start.
Right (fixed) cup threaded in the opposite direction. 		Cup diameter is slightly too large, usually won't start. Diameter matches, but thread pitch does not. Will bind after only a few threads are engaged.
Italian
36 mm X 24 tpi
(1.417" x 1.06 mm) 		British/I.S.O. cups fall through Made to Fit Italian shells are larger diameter, all other size cups fall right through, threads will not engage.
French
35 mm X 1mm
(1.378 x 25.4 tpi) 		35 mm = 1.378". Shell is slightly larger, thread pitch slightly finer.
Left side may seem to fit, but will be loose. 		36 mm Cup diameter is too large, thread won't even start. Made to Fit Left (adjustable) side is interchangeable.
Right (fixed) side is threaded in the opposite direction, won't fit. 		35 mm = 1.378". Shell is slightly larger, thread pitch slightly coarser.
Left side may seem to fit, but will be loose.
Swiss
35 mm X 1mm
(1.378 x 25.4 tpi) 		35 mm = 1.378". Shell is slightly larger, thread pitch slightly finer. May seem to fit, but will be loose. 36 mm Cup diameter is too large, thread won't even start. Left (adjustable) side is interchangeable.
Right (fixed) side is threaded in the opposite direction, won't fit. 		Made to Fit 35 mm = 1.378". Shell is slightly larger, thread pitch slightly coarser.
May seem to fit, but will be loose.
Raleigh
1 3/8" X 26 tpi
(34.9 x 0.977 mm) 		Diameter matches, but thread pitch does not. Will bind after only a few threads are engaged. 36 mm Cup diameter is too large, thread won't even start. Cup diameter is slightly too large, usually won't start.
Right (fixed) cup threaded in the opposite direction. 		Cup diameter is slightly too large, usually won't start. Made to Fit

Freewheel Threading

Type Inch Metric
Italian 1.378" x 24 tpi 35 x 1.058 mm
ISO 1.375" x 24 tpi 34.92 x 1.058 mm
British 1.370" x 24 tpi 34.80 x 1.058 mm
French 1.366" x 25.4 tpi 34.7 x 1 mm
Metric BMX 1.181" x 25.4 tpi 30 x 1 mm

French and Metric BMX freewheels thread don't work with anything else.

ISO, English and Italian are all semi-interchangeable, but it you shouldn't go back and forth between different types of freewheels on the same hub repeatedly.

Headset Threading

Threaded Headsets/Steerers
in order of frame cup outside diameter, crown race inside diameter, threads per inch, and steerer O.D.--
the dimensions which affect headset compatibility with frame and fork.
Crown race seat of fork can be milled smaller, frame bearing seats milled larger.
Standard Frame Cup
Outside Diameter 		Crown race
Inside diameter 		Steerer O.D in mm Threads
Per inch 		Stem diameter,
Steerer I.D. 		Notes
1" J.I.S. 30.0 mm 27.0 mm 25.4 mm 24 22.2 mm (7/8") Older or lower-quality bicycles from Asia. Can be milled to ISO standard. ISO and other 30.2 mm O.D.cups are a very tight fit into the head tube; best mill it to avoid damage.
1" Raleigh 30.0 mm 27.0 mm 25.4 mm 26 22.2 mm (7/8") Proprietary size used on Raleighs made in Nottingham, England. ISO and other 30.2 mm O.D, frame cups are a very tight fit into the head tube; best mill to avoid damage.
1" ISO Standard 30.2 mm 26.4 mm 25.4 mm 24 22.2 mm (7/8") This is the standard 1" size.
1" Professional/
Campagnolo 		30.2 mm 26.4 mm 25.4 mm 24 22.2 mm (7/8") Obsolete. Threads are cut at 55 degrees, but an ISO headset can be used.
1" Italian 30.2 mm 26.5 mm,
27.0 mm 		25.4 mm 24 22.2 mm (7/8") Obsolete. Threads are cut at 55 degrees, but an ISO or J.I.S. top headset can be used. Fork can be milled to ISO.
French 30.2 mm 26.5 mm,
27.0 mm 		25.0 mm 25.4
(1 mm) 		22.0 mm Obsolete. French steerers usually have a flat filed on the back, rather than a grooved keyway as with other threaded systems. The bottom headset parts wear faster; you can replace them with ISO parts and use the old top headset.
East German (DDR) 30.6 mm 26.8 mm
(1 1/8") 		26 mm 26 22.0 mm Very similar to or the same as Austrian. 0.2 mm discrepancy may result from measuring the I.D. of the head tube (press fit). See page on German site.
Austrian 30.8 mm 26.7 mm 26 mm 25.4
(1 mm) 		22.0 mm These are found on bicycles sold by Sears, made by Steyr in Austria. Higher quality Austrian bikes use English/ISO.
BMX/ O.P.C. bikes 32.6 mm
(varies) 		26.4 mm (varies) 25.4 mm 24 21.15 mm
(.833") 		Used mainly on bicycles with one-piece cranks, also some early mountain bikes.
French Tandem Let us know, if you do! 28 mm Let us now, if you do! 25.4
(1 mm) 		22.0 mm Obsolete and rare.
1 1/8" 34.0 mm 30.0 mm 28.6 mm 26 25.4 mm (1") "Oversized" (This size is more often used for threadless systems.)
Moulton 30.2 mm top,
36.4 bottom 		33.0 mm 25.4 mm 24 22.2 mm
(7/8") 		Moulton Mark III and earlier. Top headset is standard ISO.
1 1/4" 37.0 mm 33.0 mm 31.8 mm 26 28.6 mm (1 1/8") Mainly used on tandems

Metric threads are specified by diameter followed by the thread pitch (distance between threads)

For example, the common "M5" thread used for water bottle mounts, cable anchor bolts, fender/rack eyelets, shifter mounts etc. bicycles is more specifically described as "5.0 x 0.8" which specifies a 5 mm diameter, with threads 0.8 mm apart.

Similarly, the common "M6" thread used for brake mounting bolts, threadless stems, many seatpost bolts and so forth is actually "M6.0 x 1.0" That's 6 mm diameter, threads 1 mm apart.

Normal coarse metric threads are commonly designated with the letter "M" followed by the diameter, with the thread pitch understood. For example:

  • M2 = 2.0 x 0.40 mm
  • M2.5 = 2.5 x 0.45 mm
  • M3 = 3.0 x 0.50 mm
  • M3.5 = 3.5 x 0.60 mm
  • M4 = 4.0 x 0.70 mm
  • M5 = 5.0 x 0.80 mm
  • M6 = 6.0 x 1.00 mm
  • M8 = 8.0 x 1.25 mm
  • M10 = 10.0 x 1.5 mm
  • M12 = 12.0 x 1.75 mm
  • M14 = 14.0 x 2.00 mm

To give another example, the common size derailer hangers and chainring stack bolts and is 10 x 1.0 mm. This is a fine thread, not a standard coarse thread, so it would be incorrect to refer to this simply as "M10" since the standard pitch for M10 is 1.5 mm.

Threadless Headsets

Headsets, such as the Dia Compe "Aheadset" ® which fit a smooth sided (threadless) fork steerer.

See the Headset entry for details and adjustment instructions.

Three-piece Cranks

Most bicycle crank sets are of the three-piece type, the three pieces being the left crank, the axle, and the right crank with chainwheel(s). Three-piece cranksets use either cotters or a tapered cotterless attachment. There are also two-piece crank sets and one-piece crank sets.

Thumb Shifter

thumbshift
thumbshift

The original style of shifter used on mountain bikes, up until the early '90s.

When the Shimano Rapidfire ® and Sun Tour X-Press ® shifters hit the market, confusion resulted, because these, too were operated by the thumbs. This confusion persists, so it is a good idea to avoid the term "thumb shifter." The newer term for these is "top-mount" shifters, as opposed to "below-the-bar" shifters, such as Rapidfire.

Tiller Effect

On bicycles where the handlebars extend well back from the steering axis, such as many cruisers and especially direct-steering long wheelbase recumbents, turning the handlebars also causes both grips to move noticeably to the side. In steering bicycles that suffer from tiller effect, you need to move your hands sideways to the side opposite which you're steering. Tiller effect can thus limit how tightly you can corner, as your arm length may limit the amount by which you can turn the handlebars. On an upright bicycle where some of the rider's weight rests on the handlebar, tiller steering makes it awkward to ride with only one hand on the handlebar, because of the tendency of the weight to push that end of the handlebar forward.

T.I.G. Welding

Tungsten Inert Gas welding. A form of welding by the use of an electric arc. The area being heated is bathed in an inert gas to prevent oxidation.

T.I.G. welding is commonly used to build lugless bicycle frames. Most current bicycle frame production is done by T.I.G. welding.

Timing Chain

see Sync chain.

Time Trial

A race in which competitors start one-at-a-time, usually at 30-second or one-minute intervals. The winner is the cyclist who completes the course in the shortest time. Since drafting is not allowed in an individual time trial, there are no team tactics; it is just the cyclist against the clock, hence the sobriquet "the race of truth."

The cycling leg of a triathlon is a form of time trial.

There are also team time trials, usually involving teams of 4 or more, taking turns leading and drafting each other. Team time trials require great precision in rotating position within the team.

Time trials are held both on the road and on the track. Bicycles made for time-trial use are designed to be as aerodynamic as possible, even at the expense of degrading handling characteristics and rider comfort. Since riders are on their own, there is no need for fancy maneuvering as there is in a peloton.

Tire

People usually think that tires are made of rubber. This is understandable, because rubber is all that you can see.

A tire is actually made up of three parts:

  1. The beads are two hoops of strong steel wire (or, sometimes Kevlar ®.)
  2. The cords are cloth, forming the body of the tire, woven between the two beads. Most modern tires use nylon cords.
  3. The rubber covers all the other parts. The rubber on the part that contacts the road is thicker, and is called the tread.

A bicycle tire is not airtight by itself, so it uses an inner tube, which is basically a doughnut-shaped rubber balloon. The inner tube has a valve to allow you to blow it up. (Some newer tires are tubeless, like car tires, but tubeless tires are not very common as of yet. There is a complication in that the tire beads are much narrower than with car tires, so it is harder to form a seal. Time will tell.

This site includes an extensive article on Tires and also an article explaining the different Tire Sizing systems.

Tire Lever, Tire Iron

A special tool for prying the bead of a tire over the rim. Most tire levers have a rounded end which slips between the rim wall and the tire. The other end of the lever is bent and has a notch. Once you have inserted the first tire lever and pried one section of the bead over the edge of the rim, you can hook the other end around a spoke. This leaves your hands free to stick another lever in, usually two spokes over from the first.

One or two tire levers are usually enough to get all but the most recalcitrant tire beads over the rim, but in extreme cases you may need three. When the third is in place, the middle one can be removed and re-inserted farther over. Tire levers are usually sold in sets of three, since you never need more than three.

Since most newer tire levers are made of plastic, the term "tire iron" is a bit anachronistic.

Tire Saver

A frame/fork-mounted device designed to brush sharp debris from the tread of tires before it can penetrate through to the inner tube. Tire savers usually attach to the brake center bolt, and are commonly made from recycled spokes.

Titanium

One of the better materials for making bicycle frames. It is very strong, rustproof, and light.

See my Article on Frame Materials.

Titanium Nitride (TiN)

Titanium Nitride is a very hard ceramic surface treatment used on metal parts to reduce friction and extend wear life.

See Wikipedia for details on this.

Toe Clips

Toe Clips are stirrup-like devices that attach to pedals. They are normally used with leather or fabric straps. Actually, the straps are more important than the clips, but without the clips it is nearly impossible to get into the straps, because the clips hold the straps open, allowing the rider to slip into them.

Toe Clip Overlap

On many bicycles, especially those with smaller frames and full-sized wheels, it is possible for the front fender or tire to bump into the rider's toe or to the toe clip. Some people worry a lot about this, but it is rarely a significant problem in practice.

The only time it can happen is when the handlebars are turned quite far to the side, as only happens at very low speeds.

Many, many people ride bicycles with fairly severe overlap with no practical problems, sometimes having to make a slight adjustment to their pedaling habits at very slow speeds.

On smaller-size bikes with full-sized wheels, it is usually impossible to eliminate overlap without causing adverse fit/handling issues.

Toe-In

When a brake shoe presses against a moving rim, the pull of the rim causes the brake arm to flex a bit. If your brake shoes hit a stationary rim perfectly straight and squarely, the flex of the brake arm will cause the rear edge of the brake shoe to do the brunt of the work. The front edge of the shoe may not even be engaging the rim under hard braking.

Good practice in installing brake shoes is to "toe them in", so that the front part of the shoe hits the rim first. As the brake arm flexes under real braking, it will permit the whole surface of the brake shoe to engage the rim.

Toeing in of brake shoes can also reduce the annoying squeal some brakes make when in use.

Brake shoes that are longer to the rear of the post will press more evenly on the rim. Most newer brake shoes have special washers with curved surfaces to allow you to adjust the angle of the shoe to the rim. Older brakes relied on brute force, typically bending the brake arm with an adjustable wrench. That is not a good idea with aluminum brakes-- it can initiate cracking, which leads to failure.

Also see Jobst Brandt's article on toe-in and brake squeal.

Tops

The parts of a drop handlebar above the brake levers.

Top Pull

A style of front derailer operated by a cable coming down from above, as opposed to a traditional "bottom-pull" unit, operated by a cable coming up from below. Top pull derailers are mainly used on mountain bikes, because they permit the designer to avoid running the gear cables by the bottom bracket, where they are exposed to spray from the front wheel.

Top-Swing ®

Most front derailers use a parallelogram which is fixed (attached to the derailer body) at the top, with the moveable cage attached to the bottom link of the parallelogram. Many of the newer Shimano units are built "upside down": the bottom of the parallelogram is fixed in place and the cage attaches to the top link.

A peculiarity of Top-Swing ® derailers is that the limit stop adjustment screws are reversed, so that the outer screw limits inward travel, and vice versa.

Top-Swing ® derailers clamp on to the seat tube lower down than bottom-swing units. (Shimano E-type derailers don't even attach to the seat tube, but are held on by the bottom bracket mounting ring.) Some frames made for use with top-swing derailers will not permit the installation of conventional bottom-swing derailers, because there's a bottle braze on in the way. Some suspension frames also require a top-swing front derailer for clearance reasons.

Top-Swing ® or bottom-swing derailers can be (and are) made in either top-pull or bottom-pull versions. (This has to do with the direction from which the cable approaches.)

Top Tube

The frame tube that runs horizontally from the top of the head tube to the seat cluster. Up until the 1980's, most high quality bicycles were built with the top tube exactly horizontal. Newer frame designs commonly have sloping top tubes, higher at the front. This is particularly common in smaller frame sizes.

The length of the top tube is probably the most important dimension in providing a comfortable fit. See my article on Frame Sizing.

Torsion, Torque

A force applied in the form of a twist, rather than a straight push or pull. "Torsion" is used to indicate that the force involved it a rotary force. "Torque" is a measurement of torsional force.

Torque is the linear force times the radius at which it is applied. For example, a 10-pound force applied two feet from the axis produces the same torque as a 2-pound force applied ten feet from the axis.

The standard units for measuring torque are pound-feet or Newton-meters. Note that the force unit goes first, so as not to be confused with energy/work measurements. A common error is to refer to "foot-pounds" instead of pound-feet of torque. This is not strictly correct, since the foot-pound is a unit of energy/work, not torque.

Also see the more extended article about torque.

Torque Wrench

A "torque wrench" is a type of wrench with a built-in spring-loaded indicator that gives a numerical readout of the amount of torque being applied through it.

This is primarily an automotive tool, especially useful for applications involving crushable gaskets which must be tightened evenly.

Torque wrenches are never needed for bicycle work, although they can be a useful training aid for inexperienced mechanics who haven't learned the feel of a properly-tightened fastener.

[I find this mostly to be true, but many bicycle components now are accompanied with spec sheets with lists of torque settings. There are three reasons for this:

  • Consultants to attorneys measure torque values, leading to an excess of caution by the manufacturers
  • Some components made of unusual materials (carbon fiber seatposts, aluminum bolts) require lower torque settings than for other parts of the same general type.
  • In some unusual cases -- for example, quill handlebar stems -- a wedging effect multiplies the force exterted by a threaded part, and can lead to damage at torque values which would be normal otherwise.

This paragraph added by John Allen]

Also see the more extended discussion about torquing threaded parts.

Touring

"Touring" is a slippery word, and means different things to different people. This can cause miscommunication, so the word should be used with caution.

To non-cyclists, or casual cyclists, "touring" may mean riding 8 miles on a rented cruiser at a beach resort, or a fund-raising "thon" ride, or any type of riding where the principal objective is leisurely enjoyment of scenery and fresh air.

In the sense more generally accepted in cycling circles, however, a "tour" is a multi-day ride, which is not a competition or a timed event.

See also touring bicycle.

Touring Bag

touringbag
touringbag

A type of under-the-saddle bag popular in the British Isles. It attaches to special loops at the rear of the saddle, and also has a strap which wraps around the seatpost. Sometimes there is a special bracket instead to attach the bag to the saddle. This is necessary when the saddle does not have loops or has flimsy plastic loops, but it also allows the bag to be removed and replaced more quickly, and can keep a large bag up off the rear tire.

Traditional British touring bags are roughly cylindrical (oriented crossways-no attempt is made to make them aerodynamic) though they add little drag, because they are behind the cyclist. They come in a range of sizes, usually with a large main compartment and a small pocket at each end. They also feature metal rings on top of the flap to which the rider can strap a rolled-up rain cape, in case the rain stops.

Major brands are Brooks, Carradice, Karrimor and Zimbale. The better-quality bags are made of heavy black canvas, with gray"chrome" leather straps and corner reinforcements. In the USA, Dill Pickle Gear makes nice touring bags to order.

Most Brooks saddles have strong, steel bag loops. It may be necessary to rotate the springs of a sprung saddle so the straps will feed through easily past the coils. Loops can eventually cut through the straps, though some have smooth metal inserts. Brooks sells the eyelets, replacement part BYB 323, which will fit bag loops with a long, narrow (not triangular) slot.

A saddle without eyelets. The sharp edges of the bag loops
can cut bag straps.

Saddle without eyelets

A saddle retrofitted with eyelets.
Rotating the springs can make it easier to insert bag straps
on a saddle with springs.

Saddle with eyelets

Filing the loops smooth can help. Carry a pair of extra toe straps to use as replacement straps, just in case.

Pop quiz: what's wrong with this picture?

carrababy

Answer: the straps are threaded onto the springs, rather than through the bag loops -- but also, for the greatest stability, the buckles should be inside the bag, allowing it to be snugged up against the bag loops.

Straps inside bag.

straps inside bag

Bag snugged up against loops.

straps inside bag

Still, these bags are not ideal for cyclists who like to stand up and thrash their bicycles from side to side while climbing, due to sway. For the cyclist with a smooth riding style, these bags offer a good option for carrying a sizeable load on a bicycle which lacks pannier racks -- or to provide extra capacity.

This type of bag is currently enjoying a resurgence of popularity.

In case you might possibly have other questions about the picture, a further explanation is available.

Touring Bicycle

A touring bicycle is designed for comfort, durability, efficiency and, in most cases, load-carrying capacity. Touring bicycles fall into two major groupings:

  1. Loaded-touring bicycles, the classic "touring" bicycle is intended for self-supported travel, including camping and, in some cases, cooking equipment. A loaded-touring bicycle has:

A well-equipped loaded-touring bicycle will usually have:

  • Drop handlebars
  • Full fenders.
  • Front pannier rack (usually low-rider style.)
  • Rear pannier rack.
  • Lighting system (usually generator-powered.)
  • 3 or 4 bottle cages, for water and cooking fuel.

Increasingly, loaded touring is being done on modified mountain bikes, which share many characteristics with loaded tourers.

Some riders prefer to use trailers instead of panniers to carry their camping equipment.

  • Light-touring, or "credit-card" touring bicycles are intended for inn-to-inn tours, randonnées, or organized tours with sag-wagon service, in which the rider will carry perhaps a large touring bag or handlebar bag. A light-touring bicycle may be a modified road-racing bicycle, or a bicycle made for the purpose. It will usually have:
  • Conservative road-racing geometry.
  • A triple chainwheel crankset.
  • A close- or medium-ratio cluster.
  • Medium (25-28 mm) width tires.
  • Clip-on aero bars.
  • Clipless pedals.
  • "Sport-touring" bicycles are not, strictly speaking, touring bicycles at all. This is a term normally used to refer to the general-purpose "ten-speeds" (later 12-speeds) of the '70's and early '80's. These bikes were marketed as general purpose machines, and millions were sold. Millions of them are now rusting away in the back of the garages of middle America. These bicycles are characterized by:
  • 630 mm (27 inch) wheels.
  • Drop handlebars
  • Double chainwheels, usually 52/42 or 52/39.
  • 5 speed freewheels, usually 14-28 teeth.

Since these bicycles were most often sold to people for whom drop handlebars were unsuited, many of them added features to try to make the bicycle more appealing to the casual cyclist, without losing the "racer" look:

Note: the term "sport touring" is sometimes used to refer to a "light-touring" bike by cyclists too young to remember the 10-speed era.

T.P.I.

  • Threads Per Inch, the pitch of a threaded fastener.
  • Threads Per Inch of cloth. This is a common spec for tires. The higher the TPI number, the thinner and more flexible the tire fabric is. Thin-wall (high TPI) tires tend to be lighter and have lower rolling resistance, but they're more easily damaged by road hazards.

Track

An oval track, also known as a "velodrome" for bicycle racing. Track bicycles have steep angles, fixed gears, and no brakes. Common track events include match sprints, pursuits, motor-paced events and miss-and-out races. The Japanese variant, Keirin, is a major betting sport.

Track Hub

A fixed-gear hub. Track hubs have a stepped thread, with a standard 1.37" x 24 tpi thread for the sprocket, and a smaller, left-hand thread for a locknut. The idea is that if the sprocket should start to unscrew, it will turn the lockring with it, tightening the left-hand thread, preventing the sprocket from unscrewing. There are several different threads used for the left-threaded lockring, including:
English/ISO1.29" x 24 TPI
Campagnolo/Phil Wood1.32" x 24 TPI
Old French33 mm x 1.0 mm
 hub-suzuepromax

Track Mitts

British term for fingerless cycling gloves.

Track Nut

An axle nut with a built-in washer loosely riveted to it. The washer is permanently attached, but can rotate with respect to the nut. Used on high quality solid-axle hubs. Cheaper solid-axle hubs use serrated flange nuts, or plain nuts with serrated washers.

Track Nuts

Track Nuts Serrated Flange Nuts

Track Stand

The act of balancing motionless on a bicycle. This is done most easily on a fixed-gear bicycle. The rider turns the front wheel to about a 45 degree angle and balances with the cranks horizontal. So the wheel can be brought back to straight ahead even if there is toe clip overlap, the crank on the side toward which the bicycle is steered faces forward. If the bicycle starts to lean to that side, a slight forward movement of the cranks will bring the tires back under the rider's center of gravity. If the bicycle leans the other way, rolling backward will correct the lean. This is the same action as putting more weight on the left leg to avoid falling to the left, and vice versa, but it takes some practice and it is easier with a low gear.

The Guinness Book of World Records once had a category for the slowest bicycle ride, but further entries were disallowed after cyclist Dave Steed held a track stand for 9 hours. It has been reported that he later held one for 24 hours and 6 minutes.

On the banking of the track, which is bankd and where races are run counterclockwise, the front wheel is usually turned to the right. It is possible to do a track stand on a freewheel-equipped bicycle if the front wheel is pointed up a sloping section of road -- so, on a crowned road in right-side driving countries, the front wheel is turned to the left. The technique must be learned separately each way.

A cyclist who has learned both ways can ride a fixed-gear bicycle backwards, switching between a right-side track stand and a left-side track stand. The great Major Taylor once won a match sprint race in this way, by backpedaling a half turn to get behind the other racer for the final sprint to the finish. Following this, the tactic was banned, though track stands are still permitted in match sprints.

[This section expanded by John Allen.]

Traction

The frictional force that keeps a tire from skidding. A tire with good traction will be less likely to skid.

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 "squirm" 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.

Trail

Trail is the distance from the center of the contact point of the front wheel with the riding surface to the intersection of the steering axis (head tube) with the surface. The trail is a function of the head angle, the fork rake, and the tire diameter. Trail has a major effect on the handling of a bicycle. More trail increases the bicycle's tendency to steer straight ahead. A bicycle with a largish trail dimension will be very stable, and easy to ride "no hands". A bicycle with a smaller trail dimension will be more manuverable and responsive.

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

Trainer

  1. A device on which a bicycle is placed so that it may be pedaled while stationary. Generally, the front wheel rests on the floor, and there are clamps to support the rear wheel at the ax le.. A roller device rests against the rear wheel to provides resistance by way of a magnetic assembly or a fan. A trainer allows a bicyclist to build or maintain fitness when riding is inconvenient. A trainer does not, however, build smoothness of pedaling or improve balance as rollers do.
  2. A person who assists racers or other cyclists in building physical fitness -- as distinguished from a coach, who also teaches riding skills and tactics.

Transverse Cable

The horizontal cable linking the two arms of a cantilever or center-pull brake. Also called a "straddle" or "crossover" cable.

Traps

Short for rat traps.

Travel

In a bicycle suspension, the travel is the total distance that the wheel can move up and down, with respect to the frame.

Travel Agent ®

Quality Bicycle Products Travel Agent
Quality Bicycle Products Travel Agent

A stepped pulley device from Quality Bicycle Products, designed to change the amount of cable travel. The principal application of these is to permit the use of traditional short-pull brake levers with direct pull cantilevers or other brakes that are designed for long-pull levers.

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)

Note: the small-diameter pulley will fatigue the cable, resulting in fraying and failure, sooner or later.

Tread

  1. The contoured surface of a tire, used to improve traction in loose or rough surfaces. Knobby or grooved tread designs have no real value for use on hard paved surfaces, and extreme tread patterns increase drag, noise and reduce cornering traction due to squirm. Despite appearances, slick tires perform best on hard paved surfaces.
  2. The lateral distance between the pedal attachment points on a crankset. For most cyclists, the narrower the tread the better. When we walk, our footprints fall almost in a straight line under the center-of-gravity of our bodies. When we cycle, the "tread" forces our feet to be exerting their force farther apart than they are designed to do. Some theorists blame this for knee and hip problems experienced by some cyclists, but the jury is still out on this. A wider "tread" also creates a greater sideways force when pedaling out of the saddle, so the rider must exert more upper-body strength when riding "en danceuse".

    A wider "tread" decreases pedal-ground clearance when the bicycle is banked over into a tight turn.

    ("Tread" in this sense is sometimes referred to as "Q-factor.")

Tread/Q Factor

Trekking Bicycle

This seems to me to be basically a bit of marketing hype. "Trekking" bikes are basically indistinguishable from 700c "hybrids" except that they come with a lot of accessories that are not stock on a hybrid, such as fenders, racks and generator lighting systems.

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

A form of bicycle acrobatics, in which the object is to navigate a course that is as close to un-rideable as possible, without putting a foot down (known as "dabbing.")

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 aggressive 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 down in the manner of a pogo stick. In this way it is possible to climb stairs sideways, etc.

Triathlon, Triathlete

A three-part race, usually consisting of a swim, a cycling stage, and a run.

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.

Sturmey-Archer trigger shifter
Sturmey-Archer trigger shifter

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 arenot governed by the U.C.I. and there are very few restrictions on allowable equipment.

Trigger shifter

A shifter for a Sturmey-Archer or Sachs internal-gear hub, mounted on the handlebar, and designed to be operated by the right index finger. This was probably the first handlebar-mounted shift control ever, and replaced the older quadrant shifter sometime before WWII.

Trim

To make a fine adjustment to the position of the front derailer cage. This is sometimes necessary as the rear derailer is shifted because changes in chain angle can cause the chain to rub on the front derailer cage.

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 , the "Symmetric", 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.)

Triple

A crankset with three chainrings. The smallest, inner chainring is commonly referred to as a "granny gear."

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

Triple Butted

Double butted, but with different thickness butts on each end.

This term may apply to frame tubing or to spokes.

Triplet

A tandem for three riders.

True, truing

A "true" wheel is one in which the rim is perfectly concentric and runs along a plane perpendicular to the axle.

A wheel which is "out of true" vertically will be out of round, and will give a bumpy ride even on a smooth road. If it has splayed sidewalls, it will also cause pulsation of a rim brake.

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.

Troxel

Very old-established American manufacturer of bicycle saddles. More recently, they're more known for accessory baby seats.

TTT

Techno Tubo Torino (Technical Tubing Turin) Prominent Italian manufacturer of handlebars and stems.

Tub

British slang term for a tubular tyre

Tube (inner)

Inside of most modern bicycle tires you will find an inner tube, which is basically a rubber balloon with a valve that fits through the rim so that you can inflate it.

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.

Andy tube will slowly lose pressure as air seeps out through the rubber. Most tubes are made of synthetic (butyl) rubber. The can usually go a week or more without significant loss of pressure. Some tubes have been made of natural latex rubber, for light weight and more flexibility -- but they need to be pumped up at least once per day.

Tubie

Infantile slang term for a tubular tire. Using this term will make you sound like an idiot.

Tubing (frame)

Traditional bicycle frames are built out of metal tubing, generally aluminum, steel or titanium.

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. Only welding is used for aluminum or titanium frames.

Tubular

A type of tire mainly used for racing. A tubular tire has no beads; instead, the two edges of the carcass are sewn together (hence the term "sew-up") with the inner tube inside. Tubulars fit only on special rims, where they are held on by cement.

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 with good clinchers in most cases, due to imperfect contact of the glued section with the rim, so there is rubbing.

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 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. The smaller sizes are very poorly standardized; tires and rims of nominally the same size may not fit one another.

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

Turkey Wings

Sarcastic slang term for extension levers.

Twenty Niner

The so-called "29 inch" tire size is not actually a new size, it is just a new marketing term for 622 mm (700C) wheels with fat 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 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.

Twenty-seven Five (27five)

Idiotic, confusing marketing buzzword referring to the 584 mm (650 B / 26 x 1 ½") Please do not use this bogus designation, let it die a well-deserved death. Tire-sizing is confusing enough without making up new designations for existing sizes.

Two-piece Crank

A style of crankset in which the axle and right crank/chainwheel are a single part, and the left crank attaches to the axle either with a cotter or by tightening a pinch bolt that holds the crank to a splined axle. These were formerly usually found on low-quality bicycles and exercise machines of European manufacture. The most common type is known as "Thompson."

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.

Tyre

British spelling of tire

Spoke divider
Copyright © 1998, 2008 Sheldon Brown
Original: https://www.sheldonbrown.com/glossary-t.html · Reproduced on en.wikipedalia.com with permission, all rights reserved.
Retrieved from "https://en.wikipedalia.com/index.php?title=Sheldon_Brown%27s_Bicycle_Glossary/T&oldid=5591"