Sachs was a European conglomerate that bought up many of the formerly independent French parts makers, including Atom/Maillard/Normandy (hubs, pedals, freewheels) Huret (derailers) and Sedis (chains.)
Sachs also made multi-speed internal-gear hubs in 3-, 5-, 7- and 12-speed versions. Their "3 x 7" hub was a hybrid system, a 3-speed internal hub that took a 7-sprocket cassette, providing 21 speeds with only one chainwheel.
Sachs formerly also made kick-back hubs and a "2 x 6" hybrid hub, the "Orbit". The one clear area of domination for Sachs was its chains, which were generally acknowledged to be the finest available.
Sachs was the major European competitor to Shimano for the general bicycle parts market. Their parts in general were quite good, and stand up well in comparison with Shimano equivalents, although exchange rate problems sometimes make them less affordable. The bicycle division was sold to the SRAM Corporation, in November 1997. Most of the products formerly called "Sachs" are now called "SRAM." Up-to-date information is on the SRAM site.
Frequently called a "seat", a bicycle's saddle is not intended to support the rider's entire weight. Traditional saddles are made of leather stretched over a metal frame, hammock style. This type of saddle requires care and careful breaking in, but when this is done, the classic leather saddle molds itself to fit the particular anatomical shape of its rider.
Leather saddles are particularly well suited to long-distance tourists, and have their greatest advantage in hot weather, because they are porous and able to breathe, unlike plastic saddles which have closed-cell foam (also known as "gel") as a cushion. There is a more extensive article on Leather Saddles on this site.
A touring bag, which is attached to the rear of a bicycle saddle. "Touring bag" is less confusing, because the saddlebags used on a horse look much like bicycle pannier bags, which sit to either side of a bicycle wheel.
Society of Automotive Engineers, a quasi-official trade association which establishes standards for materials and parts used in the automotive industry. This body has jurisdiction over screw threads and wrench sizes based on the inch system, so inch-based fasteners are sometimes referred to as S.A.E. sizes.
A conventional bicycle, with wheels of similar size and chain drive. When the modern style of bicycle was replacing the high wheeler, in the late 1880's, the new style was mainly noted for its greater safety compared to the older design.
The two breakthroughs that allowed the safety bicycle to obsolete the high wheeler were Dunlop'spneumatic tire and chain drive.
A car or truck that picks up or otherwise assists riders who have had to stop riding due to fatigue, injury, or mechanical failure. This is primarily a touring term, racers call the corresponding vehicle the "broom wagon."
Some people believe that the term derives from the verb "sag", others maintain that it is an acronym for "Support And Gear."
Santana is the world's leading manufacturer of high-end tandems. Starting in the late 1970s under the leadership of Bill McCready, Santana virtually re-invented the tandem, which had been in decline since the Second World War. Before Santana came onto the scene, there had been low-quality nass-produced American tandems, mediocre mass-produced French ones and a few high-grade custom ones from English and European makers. Santana undertook a major rethinking of tandem design. A major contribution was to discard the idea that a tandem should be as much like a solo bike as possible, with a short wheelbase for good handling. By increasing the room for the stoker, Santana made the tandem much more pleasant to ride. Also, Santana placed a premium on torsional frame stiffness, which is heavily tested in a tandem, and pioneered in assembling top-quality components and sourcing special items such as 48-spoke hubs and rims that made for reliable wheels.
Standard automotive-style air valve. The other, skinny kind is called "Presta".
There is a third type of valve, very rarely seen in the U.S., which has a bottom similar to a Schrader and necks down to about the size of a Presta. This is a Woods valve, formerly popular in the British Isles and Asia.
A fast, reckless cyclist who scares horses and old folks. This term was current in the late 19th century.
In the early 1990s, Ibis made a small run of retro-style fixed-gear bikes for street use, which they called the "Scorcher." This term was picked up by the media and caused a brief boomlet. The result is the use of the term "scorcher" to refer to a fixed-gear bike with cruiser-type flat curved handlebars, often without brakes.
A fastener with external threads, usually with a slotted or recessed head. Strictly speaking, it's only a screw if the threads extend the full length of the shaft.
If the threads do not extend full length, technically it is a "bolt" but only pedants insist on this distinction.
A "sealed" bearing is one which has rubber or plastic gaskets to prevent the entry of dirt. In the bicycle industry, the term "sealed bearing" is often used colloquially to refer to a cartridge bearing. This can be confusing to a consumer who may think that a hub is a high-tech cartridge-bearing unit, when it is actually a normal cup-and-cone bearing with a plastic dustcap.
The junction between the seat tube, the top tube and the seat stays of a frame. The seat cluster usually also incorporates the seatpost binder bolt that clamps the seat tube or seat lug tight around the seat post to secure it.
Metal tubing used in bicycle frames can be manufactured in two different ways:
Seamless tubing begins as a solid round bar, which is heated to a workable temperature, then pierced by a mandrel. It goes through a series of rolling operations to bring the diameter and wall thickness to the desired sizes.
Seamed tubing begins as a strip of flat sheet metal, which is curled into a tubular shape, then the edges are welded together. After this, the seamed tubing may also go through various rolling steps. Seamed tubing is cheaper, but weaker than seamless tubing. Generally, all better-quality bicycle frames are made from seamless tubing.
The tubular support that holds the saddle. The seatpost telescopes into the seat tube of the frame, providing the adjustment for saddle height. It is usually secured by a pinch bolt at the top of the seat tube.
Older seatposts, and those on cheap bicycles, are basically pieces of pipe, perhaps with a different diameter (usually 7/8" / 22.2 mm) at the top end. A separate clamp attaches the saddle to this type of seatpost.
Modern, high-quality seatposts have the saddle clamp mechanism built into the top of the post. This type is also commonly referred to as "microadjusting" because it permits a finer degree of adjustment of the saddle angle.
Seat posts come in a wide range of diameters, from 21.15 mm to 31.8 mm. Low end department-store bicycles are typically 21.15 mm (13/16"). Most bicycles with one-piece cranks, including most BMX machines use this size. Bicycles with standard-size (1 1/8" / 28.6 mm o.d.) seat tubes usually have seatposts between 25.4 (1") and 27.2 (1.07") in diameter. Seatposts typically come in sizes with even-numbered tenths of millimeters (26.0, 26.2, 26.4...).
For standard-sized seat tubes, the larger the seat post the thinner the tube. Thus, a larger seatpost size is often an indicator of a lighter, fancier frame.
An adaptor to allow a saddle with four frame rails to mount onto a standard one-bolt "microadjust" type seat post.
The adaptor consists of a grooved brass plate which fits between the upper and lower rails, so that the vertical clamp bolt doesn't distort them by squeezing them together. This accessory includes a longer than normal bolt, and is primarily used for mounting wider Brooks leather saddles, such as the B-72 and B-66.
The spline pattern was chosen to permit the spindle to fit through a Front-Freewheel bearing set, because a standard-sized square-tapered bottom bracket spindle would not fit.
This design turned out to be rather unreliable, due to the small diameter of the splines, and Shimano abandoned the system. Shimano did continue to supply spare parts for many years thereafter, but these are no longer available.
Self-energizing brakes use some of the braking force to provide a "power assist" to the brakes. The best-known self-energizing brake is the Scott-Peterson (Sun Tour)cantilever, which has a steep, helical thread as its pivot, so that the forward force exerted by the rim against the pads helps cause the pads to press harder than they would from hand effort alone.
Self-energizing brakes are quite controversial, because they can have a non-linear response, which may lead to wheel lock-up.
"Selle" is Italian for "saddles." It is the plural of "sella," saddle.
There are several Italian saddle makers whose corporate name begins with "Selle", including Selle Italia, Selle Royal, Selle San Marco and others. Sometimes people try to shorten these names and say "Selle saddle", which actually makes no sense.
Equipped with serrations ("teeth", from the Latin word for "saw" ) to improve grip. Cone locknuts, washers, jaws of vise grips, pliers, pipe wrenches, saddle clamps are serrated.
A screw or bolt threaded into a ring or collar, designed to press against the shaft that the collar surrounds, so that the ring is held solidly against the shaft.
Some tandem eccentric bottom brackets use set screws to hold the eccentric in position. A very few (mostly antique) bicycles also use set screws to secure the seatpost in the frame.
A dimension sometimes used in specifying European frames. This is the horizontal distance from the seat tube/top tube intersection to a point directly above the bottom bracket. It is sometimes used as an alternate measurement to the seat tube angle.
The offset of the clamping parts of a seatpost behind the centerline of the seatpost.
An alternative drive system, replacing the chain and sprockets with right-angle bevel gears and a shaft running inside the right hand "chainstay."
Shaft drive was briefly popular around 1900, and occasional attempts are made to revive the design. Unfortunately, shaft drive turns out to have more problems than advantages.
A shaft drive requires heavier frame construction around the bevel gears to maintain their precise alignment under load. The drive system is heavier and less efficient than a good chain drive.
For reasons of clearance, the bevel gears of a shaft drive bicycle must be considerably smaller than the typical sprockets used with a chain drive. The smaller size of the gears causes an increase in the stresses on the whole support system for the shaft. This problem is exacerbated because the stresses from the shaft drive are not perpendicular the triangulated structure of a bicycle frame, and so are not well-resisted. .
Most of the advantages touted by proponents of shaft drive are only advantages compared with open-chain, derailer gear systems. Many proponents of shaft drive use specious (if not dishonest) arguments "comparing" shaft drive systems with derailer gear systems. Any such comparisons are meaningless, it's like comparing apples and locomotives.
A valid comparison of shaft vs. chain drives can only be made if both bikes use the same type of gearing, whether single-speed or with an internal gear system.
These same advantages can be obtained with chain drive using a fully-enclosing chain case, as with old English roadsters and many current Dutch bikes.
Shaft drive proponents also often compare sealed, enclosed shaft drive systems with open, exposed chain drive systems. This is also a misleading comparison. All of the advantages claimed for shaft drive can be realized by the use of a chain case.
Shimano trademark for a chainstay protector with a projection near the front that was intended to keep the chain from getting jammed up if it overshifted the small chainring. This projection was triangular and resembled a shark's dorsal fin, hence the name.
This product was made of black plastic, with a peel-and-stick backing and a zip tie to hold it to the chainstay.
During the late '80s when there was a fad for mounting U-brakes under the chainstays. Shimano's Shark Tooth was a small plastic part that mounted to the right hand U-brake boss as an anti-chain-suck device.
A brake bolt nut for recessed brake mounting and which is extended and threaded all the way through so a bolt can be inserted from the outer end to support a fender. The term has become generic.
The hand control for a gear shifting system. I used to object to this term, because it is actually the derailer or the internal hub that does the real shifting, and the part commonly called the "shifter" is only the control mechanism. I preferred the term "shift lever".
Because of the increased popularity of twist-grip type controls, which are not levers, I have reluctantly come to accept the common usage of the term "shifter" to refer to the hand control.
The leading manufacturer of bicycle parts. Shimano has come to dominate the industry, and to have a near monopoly on many parts categories. Shimano gets a lot of bad press, being perceived as the Goliath of the industry.
Shimano achieved this position because it has the most successful research and development program in the industry. Shimano pioneered many key technologies:
Indexed shifting Shimano was not the first to develop indexing, but Shimano's Positron and S.I.S. were the first practical systems that achieved commercial success.
Cassettefreehubs Shimano was not the first with a cassette hub, but did pioneer the placement of the right-side axlebearing outboard of the freewheel mechanism, virtually eliminating the problem of bent axles, and making possible reliable hubs with 8- and 9-sprocketclusters.
Hyperglide and Interactive Glide clusters These developments did more to improve rear shifting than any change in derailer design.
Unfortunately, Shimano's pursuit of high performance has been somewhat at the expense of versatility. For example, to reap the benefits of Hyperglide or Superglide, you need to use one of the specific combinations of sprocket sizes designed to work together. While Shimano offers a pretty good selection, it doesn't have the perfect combination for every rider.
Shimano Date Codes:
Many Shimano parts feature a two-letter date code, indicating the year and month of manufacture. More information on specific Shimano models and technologies is on a separate Shimano Page. The date codes are explained here on the Vintage Trek site.
Shimmy is a term for a harmonic shaking of the bicycle, which usually occurs at a fairly high speed. Shimmy can be very scary, and can lead to loss of control.
All bicycles are subject to shimmy under the right (wrong) circumstances, but it is more pronounced in some than in others.
A brake caliper that has one arm pulled by the inner cable, the other pushed by the cable housing. Usually, the cable runs down one side and both cable arms are on the same side of the caliper. Some sidepull brakes such as the Scott Superbrake, however, have both cable arms above the pivot, so the cable approaches from one side.
Single-pivot side-pull brakes have both arms pivoted on a central point, usually the same bolt that holds the caliper unit to the frame of fork.
Dual-pivot side-pull brakes have a separate pivot for each arm. Dual-pivot brakes usually have more mechanical advantage than single-pivot units, but they don't track out-of-true or irregular rims as smoothly as single-pivot units.
V-brakes are technically sidepull designs also, but this term is not normally used for them, since they are a type of cantilever, not caliper brake.
Defunct French component manufacturer, one of the earliest makers of derailers. They are best known in the U.S. for the cheap plastic derailers supplied on millions of Bike Boom ten speeds.
Simplex also made a "Rétrofriction " down-tube shift lever that is considered by many to be the finest pre-index shift lever ever.
Many newer drop handlebars have an indented groove or grooves in the curved section above the brake levers.
Single-groove handlebars have such a groove along the front edge only, to accommodate the brake cable running from a modern "æro" brake lever.
Double-groove handlebars have, in addition, a groove on the rear edge of the bar, to accommodate the shift cables from Campagnolo (or Sachs) Ergo shifters. If a double-groove handlebar is used without Ergo shifters, it is a good idea to tape a short length of housing into the groove, or to use a special rubber filler piece made for the purpose.
While any bike that doesn't have multiple gears is technically a "single-speed" bike, current use of the joined word "singlespeed" generally refers to a bike with a one-speed freewheel and hand brakes, distinct from both one-speed cruisers (these have coaster brakes, not freewheels) and fixed-gear machines.
(As far as I know, I was the first to deliberately remove the multiple-speed gearing from a mountain bike to make it simpler, lighter and more reliable...if I do say so myself!)
A trail, such as a hiking trail, consisting of a single rut or path; this is as distinct from doubletrack, which refers to dirt roads or other routes made by and accessible to four-wheel vehicles.
An obsolete type of tubeless tire. Similar to a tubular, but made like a loop of garden hose. They were held on to wooden rims by shellac. This type of tire was obsolete by the end of the 1920's. The most common size was 28 x 1 1/2. A flat could only be repaired by inserting a plug from the outside; damage to the fabric required professional repair in a bicycle shop.
The rim diameter is about the same as standard tubulars , though few tubulars are as wide as the typical single tube. Reportedly, however, tubulars can be mounted on singletube rims. I haven't actually tried it, can't guarantee that it will work.
Single-tube tires were forced on the U.S. market by a monopoly that excluded the better European clincher tires. Because single-tube tires were so difficult to repair, they drastically reduced the appeal of bicycling in the USA -- as is clear from a comparison of levels of bicycle use in the USA and Canada, where good European tires were available.
Siping is the use of narrow grooves in the tread of a tire. The purpose of this is to allow water to escape instead of being trapped between the tire and the road, causing "hydroplaning."
Bicycle tires have such a small contact patch and run at such high pressures that hydroplaning is an imaginary problem, even with completely slick tires.
In a quick-releasehub, the skewer is the shaft that runs through the middle of the hollow axle, and the associated hardware, including the quick-release cam and the acorn nut.
A rod used to help maintain alignment in a stack of elastomer bumpers in an elastomer suspension fork.
Fixed-gear riders who make a habit of doing "skip stops" wear the rear tire out considerably faster than those who use a brake. This problem is exacerbated by certain gear ratios, because they may tend to repeatedly skid on the same section of the tire.
Riders who plan to do a lot of skip stops should consider the ratio when selecting their chainring and rear sprocket. The mathematics of this is actually fairly simple:
Simplify the gear ratio to the smallest equivalent whole number ratio. Let's call it p/q.
if the numerator, p, of the reduced gear ratio is even then the number of skid patches is q. Skid patches are evenly spaced around the tire if there is more than one.
If you are an ambidextrous skidder, and the numerator is odd, the number of possible skid patches will be doubled. The skid patches with one foot forward fall halfway in between those with the other foot forward.
Examples:
48/12 simplifies to 4/1, so there will be only 1 skid patch
45/15 simplifies to 3/1 so there will only be 1 skid patch, or 2 if you are an ambidextrous skidder.
42/15 simplifies to 14/5, so there will be 5 skid patches.
44/16 simplifies to 11/4, so there will be 4 skid patches, or 8 if you are an ambidextrous skidder.
43/15 can't be further simplified, so there will be 15 skid patches, or 30 if you are an ambidextrous skidder.
Explanation: let's look at 45/15, or 3/1. The rear wheel turns exactly 3 times for each turn of the cranks -- so, if the same foot is forward, the same place on the rear tire is always down. 1/2 turn of the cranks places the other foot forward, and turns the rear wheel 1 1/2 times. Then, the opposite place on the tire is down. Similarly for higher numbers, if the numerator of the reduced fraction is even, skid patches will be in the same places with either crank forward, but if the numerator is odd, the number of skid patches with each crank forward will be odd, and skid patches with one crank forward will interleave with those with the other crank forward. John Allen's Excel spreadsheet calculates the number of skid patches for any sprocket combination.
A rear brake also leaves skid patches. The front wheel does not skid in normal braking. A front brake also can stop the bicycle much shorter, but requires care in use to avoid pitching the rider forward: see my article on braking and turning.
A tire in which the cord of the sidewalls is only covered with a very thin coat of rubber, if any. This makes the tire more flexible, for lower rolling resistance, but the sidewalls are more easily damaged than those of blackwalls or gumwalls.
Older style of chain, with 1" pitch. This type of chain has the same number of rollers as a similar length of normal 1/2" pitch chain, but they are spaced alternately close together and far apart. Every other roller engages a sprocket tooth. This type of chain was in common use up until around World War II. See also block chain.
An 8-tooth sprocket for 1" pitch "skip link" chain (left) is equivalent to a 16 for standard 1/2" chain.
Fixed-gear riders generally need to master a technique called the "skip stop." This is a way that you can actually lock up the rear wheel using your legs alone.
If you lock one leg at the bottom of the pedal stroke, as the pedal rises it will start to lift your body upward.
When the cranks get horizontal, pull up on the front pedal, while pushing down on the rear one.
Because your body will have acquired upward momentum, when you yank up with the front foot this will temporarily partially unweight the rear wheel, making it possible to initiate a skid.
Since sliding friction is less than sticking friction, once the tire starts to skid, you will generally be able to maintain the skid until you've stopped or at least slowed down as much as you want to.
You have to really want to do it, you can't be tentative! It's easier when you're going faster.
The lower your gear , the more effectively you can "brake" by resisting with your legs.
Despite what some folks will tell you, you can not stop nearly as short this way as you can by using a good front brake.
"Slick" or "bald" tires, those with no tread pattern, or perhaps just a bit of siping, provide the best performance for bicycles which are used on pavement.
Slick tires are smooth and silent-running, and have excellent traction. They have the lowest rolling resistance of all tire styles. Many people reject them because they look slippery, but in practice, they are not. Tread patterns on road tires are purely cosmetic, and have no practical value on hard, paved surfaces.
Shimano Linear Response, a series of friction-reducing modifications introduced in the late 1980's in the Shimano 105 group. The 105 SLR brakes (the best sidepull calipers ever made, in my opinion) incorporated:
Ball-bearing caliper pivots.
Low-friction cables.
Nylon spring bumpers.
Reduced spring tension. By adding a weak return spring to the brake lever, these brakes were able to drastically reduce the tension of the caliper return spring. Since the cable was being pushed at one end and pulled at the other, a positive return function could be attained with a much lower overall spring tension, greatly improving the "feel" and sensitivity of the brake. (This aspect of the SLR design was, I believe, copied from Dia Compe, which calls it "B.R.S.".)
This system was replaced by "Super SLR" which is Shimano's name for double-pivot brakes.
A colloquial term for a pinch flat, or rim cut, taken from the resemblance between the pair of holes in the tube and the puncture wound made by the fangs of a snake.
A plain hubaxle, as opposed to a quick-release axle, which has a hole drilled through it for the quick-release skewer. A solid axle is secured to the frame by nuts.
Frame spacing is the inside distance between the two fork ends (drop outs), where the wheel fits in. This can easily be measured just by removing the wheel and holding a ruler up to the space where the wheel came out.
Hubs come with various length axles, but the axle length is not as critical as the overlocknut distance, since it is the locknuts that actually contact the frame ends. Overlocknut distance can't be measured directly without a caliper of some sort.
This frame has a spacing of 125 mm
The dropout spacing of a frame must match the overlocknut distance of the wheels that are to fit it.
Overall axle length for quick release hubs is commonly 11 mm longer than the overlocknut distance listed, 5.5 mm on each side.
In practice, the axle can be quite a bit shorter than this...even 1-2 mm protrusion past the locknuts will suffice to locate the axle properly, so, when converting a hub to the next wider spacing, it is usually not necessary to replace the axle.
In the case of steel-based frames, it is a fairly minor matter to re-adjust the spacing of a frame to make it fit a different width hub. This process is commonly referred to as "cold setting."
Bikes with gear shifts commonly have anywhere from two to 30 different "speeds" altogether. The nomenclature for designating the number of speeds is confusing and somewhat inconsistent.
For bikes with only one gear shift, it's pretty simple. The number of gears is the number of positions.
If it's an internal-gear hub, the number of speeds is determined by the internal construction of the hub.
When there are two separate gear shifters, it gets confusing. Most newer adult bikes have two derailers and shifters, one for selecting among the sprockets on the rear wheel, the other for selecting the chainwheel in front.
The traditional way for designating the number of speeds with such bikes is to multiply the number of rear positions (sprockets) by the number of front positions (chainwheels.)
Thus, a bike with 4 rear sprockets and 2 chainwheels was always called an "8 speed" (4 x 2)
In the late '50s, 5 speed rear clusters became the norm, and these bikes were typically called "10 speeds." For much of the '60s and '70s "10 speed" was practically a synonym for "bicycle."
In the early 1980s, a 6th rear sprocket became common, so those bikes would be "12 speed." If they had 3 chainrings instead of 2, they would be "18 speed."
Then it started to get confusing!
In the late 1980s, bikes started to come with 7 sprockets in back, so they would technically be either 14 speed or 21 speed, depending on whether they had 2 or 3 chainwheels. However, it was not unusual for cyclists to refer to these as "7 speed" systems, with the number of chainrings ignored.
In the early '90s, when the move to 8 sprockets in back occurred, "road" cyclists, who used two chainwheels, commonly referred to their bikes as "8-speed" (nobody remembered the 4 x 2 "8 speeds" from the early '50s.) These bikes could have been called "16 speed" but nobody did. However, touring and mountain cyclists, with 3 chainrings commonly referred to them as "24 speed."
This pattern seems to have largely continued: Bikes with two chainrings are commonly referred to by just the number in back, these days 9 or 10. Bikes with three chainwheels are more often referred to by the total multiplied number, i.e., 27 speed or 30 speed. Although a bike with 9 in back and two in front could technically be called an "18 speed", nobody does, so as not to cause confusion with 6 x 3 "18 speeds."
It is important to realize that the theoretical number of gears is not the same as the usable number of gears on a dual-derailer system, because there are some gear combinations where the chain angle is so extreme that those gears should not be used. In addition, there are often duplicated gear ratios, so a "27 speed" bike may actually only have 20 distinct, usable gears or so.
Cycle Speedway is a type of dirt-track racing mainly popular in Britain and Australia. Riders race on a flat dirt track, usually two teams of two riders at a time. The bikes are generally fixed-gear machines with mountain-bike type wheels.
A spider is multi-armed part of a crank to which one or more chainrings are attached.
With most good quality cranks, the spider is an integral part of the right crank. Older, cheaper cranks commonly have a separate spider swaged to the right crank. Some newer cassettes also use a spider to connect the sprockets to the freehub body. This is done primarily to save weight.
A ridge on a surface of a part, usually used to prevent an otherwise circular part from turning. Commonly used on freewheels and cassettes where the sprockets attach.
Many newer bottom brackets use splines where the cranks attach to the bottom bracket spindle. Cartridge-type bottom brackets also use a splined wrench to install and remove the bottom bracket unit.
Some frame tubing has internal ribs to reinforce the tube; these are sometimes also referred to as splines.
A program of indoor exercising. "Spinning ®" uses stationary cycles, with a fixed gear and a heavy flywheel. A trainer guides a group of "cyclists" using loud music to regulate cadence. In this specific context, but only in this context, "Spinning ®" is a registered trademark.
A conventional spoke has a swaged head, like the head of a nail, to keep it from pulling through the flange of the hub. Immediately after the head the spoke takes a right-angle bend, also known as the "elbow" of the spoke. (See also straight spokes) The outer end of the spoke is threaded, and a special nut called a nipple fits through the rim and screws onto the spoke threads.
Traditionally, most bicycles have had 36 spokes in each wheel. British bicycles, for years, used to use 40 spokes in the rear, and 32 in the front. This was a better system for the consumer, because the strength of the wheels was in better proportion to the stresses on them. It makes things easier for the manufacturers, however, to use the same number of spokes front and rear. This results in a front wheel that is needlessly heavy, and/or a rear wheel that is not as strong as it should be.
In the last decade of the 20th century, 32-spoke wheels became increasingly common. Manufacturers tout this as an advantage, because it saves a very small amount of weight (they don't mention that it is also cheaper!) For most cyclists, the reduced strength and reparability of 32 spoke rear wheels is a greater detriment than the very tiny improvement in performance they offer.
Formerly, spoke diameters were specified in terms of wire gauge, but the trend is toward specifying the diameter in millimeters.
Spoke length is measured from the inside of the elbow to the very end of the threads, most usually in millimeters.
Spoked wheels may be laced in several different patterns. Most wheels use the semi-tangent pattern, less common is "direct" or "radial" spoking. Some rear wheels are laced "half radial".
There are also "novelty" or fad lacing patterns, including the "crow's foot" and "snowflake" designs. These patterns are eye-catching, but have no practical advantage.
A plastic or sheet-metal disc that fits between the cluster and the right-side spokes of a rear wheel. This is intended to prevent the derailer or chain from getting caught in the spokes, possibly causing very extensive/expensive damage/destruction to the wheel, the derailer, and the frame.
A spoke protector is not a necessity on a bike that is well treated, because the derailer can't go into the spokes if it's properly adjusted and if it is not bent. Bicycles which are subjected to rough handling, however, are prone to getting the rear derailer bashed in, and in such a case, the spoke protector can prevent very serious damage.
The earliest type of bicycle brake consisted of a lever which pushed a metal shoe against the tread of the tire. The part that pressed on the tire was shaped like a flat spoon, hence the name. Spoon brakes became obsolete with the invention of pneumatic tires, although spoon brakes on the front wheel, as an emergency back-up to a coaster brake, were still in production in less-developed countries as late as the 1980's.
Sport touring bicycles occupy a middle ground between touring and road racing bicycles. The meaning of this term has been changing:
Older "sport-touring" bikes, the typical 10 speeds of the 1970's bike boom,were solid, sturdy machines that differed from touring bicycles mainly in that they didn't have as wide a gear range. They could be used for moderately-loaded touring by riders strong enough to get along without serious low gears.
Current "sport-touring" bikes are more like road-racing bicycles which have had a triple crankset added. These bicycles have low enough gearing to let aging baby-boomers still get up the hills. Most bikes in this category are not well-suited for serious touring, because their wheels are too fragile, and they often are poorly designed so that there is not adequate frame clearance for fenders and touring-width tires.
A toothed wheel or gear that is part of a chain drive.
The front sprockets are also commonly called chainwheels or chainrings. The term "sprocket" is perfectly correct to refer to either front or rear, but most adult cyclists use this term mainly to refer to the rear sprockets. The use of "sprocket" to refer specifically to a chainwheel is mainly confined to BMX usage.
The rear sprockets individually are also commonly called cogs or gears; as a group they are referred to as a block, cassette, cluster or freewheel.
The sprung/unsprung weight ratio is a critical factor in determining how well any vehicle will hold the road on rough surfaces.
The "sprung" weight is the weight of the part of the vehicle and its payload which is held up by the springs. In the case of a suspension-equipped bicycle, the sprung weight includes most of the frame, and the rider. In the case of a rigid-frame bicycle, the "sprung" weight consists of the rider's trunk and head while the rider is off the saddle, carrying his or her weight on bent knees/elbows.
The "unsprung" weight is the weight of the wheels and the parts of the suspension that move up and down with the wheels as they track over bumps.
When a bump lifts a wheel up, the spring compresses. After the wheel passes over the bump, the spring pushes the wheel back down into contact with the ground. In the case of a vehicle with a low sprung/unsprung weight ratio, such as one with heavy wheels and a light rider, the spring will not be able to push it back into contact with the ground as fast as the same spring could push a lighter wheel.
If the rider is light, the spring force will also be light, so it will not be able to push the wheel back down as fast as the stronger spring that would be used with a heavier rider could push the same wheel.
If the rider is light, but the spring is strong, the rider will not get enough benefit from the suspension, and the strong spring will lift the rider as well as the wheel.
When a knobby tire is used on a hard surface, the knobs can bend sideways under load. This effect can cause poor cornering traction, especially on tires with tall knobs at the sides of the tread. Squirm can cause a sudden and abrupt loss of cornering traction, with little warning.
A slippery abbreviation, with two different meanings:
As a trade name, it is an alternate form of Sakae Ringyo, a major Japanese maker of aluminum parts, particularly cranks and seat posts. In the 1990's, S. R. bought what was left of the bankrupt Sun Tour, and the combined companies are now known as SR-Sun Tour.
The abbreviation "S.R." is also commonly used in want ads for older racing bicycles, where it refers to the old top-of-the-line CampagnoloSuper Record gruppo.
Based in Chicago Illinois, the SRAM Corporation is best known as the manufacturer of GripShift twist-grip shifters. SRAM also manufactures derailers, and purchased the bicycle division of Sachs, manufacturer of internal-gear hubs and bicycle chains.
The name "SRAM" is an acronym from the initials of the founding partners.
The stack height is the vertical space taken up by the headset. With a conventional threaded fork, the steerer tube is longer than the head tube by some amount. If a headset is chosen with a stack height greater than this difference, there may not be enough of the steerer free above the upper bearing race for the keyed washer and lock nut to be installed. In the case of threadless headsets, the stack height also includes the height of the part of the handlebar stem that clamps to the steerer.
A family of steelalloys, usually containing 10-20% chromium, among other alloying elements. Stainless steel is rust-resistant, and very tough, but is generally not the best choice in applications where surface hardness is of primary importance, such as bearings. Stainless steel also has somewhat lower yield strength than steel alloys optimized for that characteristic, and is somewhat more difficult to weld, so it has only rarely been used for frame tubes. [Last sentence added by John Allen]
The primary bicycle application for stainless steel is for spokes. Virtually all modern high-quality spoked wheels have stainless-steel spokes.
Stainless steel is also used for high quality control cables.
Cut from a flat sheet, usually of metal, by a powerful machine which works like a cookie cutter. Cheaper dropouts and many sprockets are stamped. A piece may be additionally formed after it is stamped.
One of the prime dimensions of a bicycle, this refers to the height of the top tube above the ground. If the standover height is too tall for a given rider, mounting and dismounting are awkward and dangerous.
Conventional wisdom is that the standover height should permit 1-3 inches (2-8 cm) of clearance between the top tube and the crotch of a rider straddling the frame, for road use. For off-road riding, considerably more clearance is required. See my article on Frame Sizing.
Two members of the Starley family in England were great pioneers in the early days of cycling. James Starley was instrumental in the development of the high-wheeler bicycle. He produced the first all-metal bicycle, and invented the tangent-spoked wheel, which is used to this day. His nephew J. K. Starley designed and built the "Rover," the first commercially successful rear-drive "safety" bicycle, which is the ancestor of all modern diamond-frame bicycles.
A special nut that is designed to be hammered into the steerer of a bicycle with a thread lessheadset, such as a Dia Compe "Aheadset" ®. The adjusting bolt screws into the "Star Fangled Nut."
The star-fangled nut has two barbed steel flanges that allow it to be forced downward into the steerer, but which prevent it from moving upward.
If you ever need to remove a star nut, the easiest way is by driving it down and out the bottom of the steerer with a hammer and punch.
Star nuts are only for use on metal steerers and should never be used on carbon steerers. Forks with carbon steerers generally come with special expansion plugs that serve the function of a star nut, without the sharp edges that might damage the fragile carbon steerer.
Star nuts are available in several diameters to fit different types of forks.
An alloy of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, chromium, nickel, molybdenum, copper, tungsten, vanadium or other metals, depending on the characteristics desired. Steels used in bicycle construction are commonly alloyed with chromium or manganese and molybdenum. Chromium-molybdenum or "cromoly" (CrMo) steel, also known by the numerical designation 4130, is particularly popular for high-quality bicycles.
Although steel is used for most high-quality bicycle frames, the use of steel instead of aluminum for many parts is often the result of penny pinching. Nobody should have to ride a modern bicycle with steel rims, brakes or handlebars. The only reason steel is now used for these parts is to scrimp on costs.
This was not always the case. As recently as the 1960's, steel was favored for many of these parts, particularly by the British. Indeed, for many years, Raleigh's slogan was "The All-Steel Bicycle". Steel parts of this era were often high in quality.
The steerer, or "steering column" is the upper part of a front fork, to which the handlebar stem and the turning parts of the headset attach. The steerer is not visible on an assembled bicycle, being entirely concealed inside the head tube, headset and a thread less or pinch-bolt type stem if one is used.
Conventional stems for most bicycles with threaded headsets fit inside the steerer of the fork, and use an expander/wedge to attach to the steerer. The stem diameter must match the inside diameter of the steerer, which is usually 1/8" smaller than the nominal headset size.
"Thread less"-type stems clamp on to the outside of the steerer, so they must match the outside diameter of the steerer, which is the same as the nominal headset size.
Stoker stems for tandems are very similar to "thread less" type stems, except that they clamp on to the seat tube of the rider in front, rather than to a steerer.
Pinch-bolt type stems are not in common use any more. They work with a fork that has a steerer with a slot cut into it, and a collar with a pinch bolt or quick release. These are most often seen on folding bicycles, because this design permits the use of a quick release.
"Adjustable" stems, (also known as "Major Taylor outriggers", after the cyclist who popularized them and possibly invented them), have the handlebar clamp unit mounted on a moveable part, permitting setting different amounts of forward extension.
Standard I.S.O. size, used on the vast majority of newer bicycles. This is sometimes incorrectly called "mountain bike" size.
25.8 mm
Unofficial in-between size used by some Italian handlebar makers for handlebars designed to be usable in either ISO (25.4) or Italian (26.0) size stems.
26.0 mm
Italian standard for drop bars, other bars made to fit Italian stems and some high-end aftermarket drop bars. This is sometimes incorrectly called "road" size.
26.4 mm
Older Cinelli and Cinelli copies. Cinelli changed over to 26.0 in 1998.
27 mm
Titan (obsolete).
31.8 mm
1 1/4"
Road oversized.
"Road" vs "MTB." A common, misunderstanding makes a false distinction between "road" and "mountain" size stem/handlebar fitting. The vast majority of bicycles use the standard ISO 25.4 mm/1" size, whatever style of handlebar is used. High-end road bikes assembled with custom parts groups often use expensive aftermarket bars and stems, which do predominantly come in the Italian size, since the major makers of expensive bars/stems for road bikes are Italian. Non-Italian parts makers attempting to compete for the high end market often offer both sizes.
Height / Angle / Reach
The range of handlebar positions available from a given stem depends on its height, angle and reach (extension.) Unfortunately, measurement procedures for determining these dimensions are not well-standardized in the industry, making it difficult to compare one stem with another based on the dimensions.
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The height dimension is normally the overall height, measured along the line of the column.
Angle / rise may be measured either from the steering axis or perpendicular to it. Thus, a stem with the extension at a right angle to the column may be described either as a 90° or 0° stem.
Reach / extension is normally measured center-to-center along the direction of the extension.
The custom of measuring reach along the line of the extension means that two stems of the same nominal reach will provide a different distance between the steering axis and the handlebar center, if they have different angles.
Many newer stems use the "pop-top" attachment system for the handlebars, permitting the stem to be swapped without disturbing the handlebar grips/tape or brake/shift controls.
Note:Steerers are butted at the bottom, so the hole in the steerer is constant-diameter until near the bottom, then the walls taper inward in the butted section.
It is vitally important that the stem extender (or stem) not be inserted so far that the wedge is installed where the steerer is narrowing, or it could come loose unpredictably.
When this happens, only the edge/corner of the quill or wedge contacts the steerer, and it is trying to "grab" a slanted surface.
This is sometimes a problem on smaller frames if you try to insert the stem or a stem riser too far down into the steerer.
Illustration by Nicholas Flower
stem shifters
The term "stem" is sometimes also used to refer to a valve.
A type of shift lever which mounts on the shaft of the handlebar stem. These were popular in the late '70's and early '80's because they permitted shifting without having to lean down to reach down-tube mounted shift levers. Stem shifters, along with brake extension levers, encouraged riding using only the top of drop handlebars. This riding style was popular at the time, because many casual cyclists bought bicycles with drop bars for reasons of fashion and style, even though drop bars were not suited to their low-intensity riding style.
Unfortunately, this riding position gives rather poor control of the bicycle, mainly because the hands are too close together for good steering control. Also, stem shifters are difficult to shift precisely, because with the shifters behind the stem, there is nothing against which to rest the hand. Most stem shifters are friction shifters, worsening the problem.
Stem shifters also present a danger in a collision. Depending on what gear you have selected, stem shifters can be like having a dull knife aimed at your groin!
A Shimano buzzword standing for "System Total Integration". This normally is used to refer to Shimano's combined brake lever/shift lever systems, particularly those designed for drophandlebars. S.T.I. is similar to Campagnolo's Ergo system. S.T.I. uses the main brake lever, pushed inward, to select larger sprockets, and a smaller, auxiliary lever inside the brake lever to select smaller sprockets. [S.T.I has the advantage that it is not necessary to remove a hand from a brake lever to shift, but the disadvantage that the lever returns to the same position after every shift, so you can't tell by feel which sprockets you have selected until you get to the last one. And then you may have shifted to a crossover gear with a bad chain angle. An alternative for drop bars is bar-end shifters, which keep the hands on the handlebars, though not on the brake levers, and which move to a different position with each shift. Bar-end shifters are much less expensive, and less complicated, too. -- This comment added by John Allen]
A tandem rider who is not responsible for steering, usually the rear rider(s), as opposed to the captain. The term comes from the workers who shoveled coal to power steam trains and steamships.
A dummy brake lever hood assembly. These are designed to act as a hand rest for a tandem stoker as the brake lever hoods do on a solo with drop handlebars.
On fixed-gear bicycles that only have a single brake, some riders install a stoker lever on the other side of the handlebar for symmetry.
Originally, spokes didn't have the elbow, and they were straight from one end to the other. They required a special type of hub, which was harder to manufacture than conventional hubs. Straight spokes are also harder to lace up, and tend to revolve when the nipple is turned.
The modern bent design supplanted"straight pull" spokes in the 1890's. Since no bicycle technology ever disappears entirely, straight spokes get re-invented from time to time, but have not met with much commercial success in the last hundred years. They are seen on some "boutique" wheels.
New spokes have residual stresses manufactured into them when they are bent at the elbow. It is impossible to build a reliable wheel without neutralizing these stresses. This is accomplished by bending or otherwise applying extra tension to the spokes. For more detail on this see the stress-relieving section of my Wheelbuilding article.
A stress riser is a notch, crack or other irregularity in the surface of a part which creates a starting part for a crack or tear. A familiar household example of stress risers is cellophane: It is fairly difficult to start a tear in a straight edge of a piece of cellophane, but once a tear has started it is almost impossible to stop.
A similar effect occurs with other materials, including those used to build bicycle frames. Good design avoids placing stress risers in heavily loaded areas of the frame.
Originally a Japanese company, the first manufacturer of inexpensive cotterless cranks , and for many years Japan's leading manufacturer of cranks. Sugino cranks are generally of very good quality, like most Japanese products.
From the early '70s to the mid '80s, Sun Tour (Maeda) was the most important Japanese maker of bicycle parts. Sun Tour invented the slant-parallelogram design for rear derailers, and made the best-shifting derailers in the world for many years, until the patent ran out.
Other major Sun Tour innovations included:
"Power Ratchet" shift levers, which used a ratchet mechanism to disengage the friction mechanism from the lever when it was being pulled against the tension of the derailer's return spring. This created a lighter lever action than other friction-type shift levers.
Greaseguard ® hubs, bottom brackets and headsets. (Wilderness Trail Bikes)
Unfortunately, Sun Tour failed to maintain the inventive spirit that put it in the lead in bicycle components, and Shimano's success with indexed shifting left Sun Tour playing catch-up. Sun tour never caught up, and it became almost impossible to sell a bicycle that didn't feature Shimano shifting systems. As a result of this, along with poor customer service, Sun Tour went bankrupt in the early 1990s. For details of this story, you may read Frank Berto's article "Sunset for Sun Tour"
The Sun Tour name has been purchased and revived by Sakae Ringyo, though the new SR/Suntour parts are not compatible with the original Japanese SunTour parts.
Soudé Usine Procès, (Welded Machined Process) Mavic's name for rims which have a welded seam, with the braking surfaces turned on a lathe after welding.
Shimano's system for improving front shifting. It consists of specially-shaped teeth and ramps on the sides of some chainwheels. Superglide chainwheels, like Hyperglidesprockets, come in sets designed to work together, so you won't get the full benefit of the system if you substitute individual chainwheels.
The Top-of-the-line Campagnolo parts group of the mid '80s. It shared many parts with the Nuovo Record group, but was lightened by the use of titanium fasteners and cut-away chainrings, etc. Super Record is the most sought-after group by collectors and restorers of classic racing bicycles.
A Bianchi trademark. In the 1980s, Bianchi used a "Superset" design, where the down tube and chainstays were supposed to be a bit heavier-gauge than normal, and the upper parts of the frame a bit lighter. The idea was to stiffen up the drivetrain. This was based on standard diameter round tubing, to fit standard lugs.
The later (1990s) "Superset II" design required special lugs, because it used an oversized down tube, ovalized at the bottom, also oversized oval chainstays. Bianchi was unique in using oversized and ovalized tubing with lugged construction, because the tooling for the special lugs was quite expensive.
"Suspension" refers to devices using some kind of spring to protect the rider and/or the bicycle from the effects of riding on rough surfaces. Modern suspensions usually include some sort of damping mechanism.
In addition to adding to the comfort of the rider, suspension systems improve traction on bumpy surfaces, by keeping the tires in more nearly constant contact with the surface. (See sprung/unsprung weight) They also help protect the wheels from damage, by allowing them to spring out of the way when they hit something forcefully.
Suspension forks have more room above the top of the tire, to allow the suspension to move. Frames built for suspension forks are designed so that the bottom end of the head tube will normally be higher up to make room for the suspension fork's travel.
Suspension-corrected rigid forks mimic this geometry: they have longer blades to hold the head tube up to the same height a suspension fork would. If you desire to replace a suspension fork with a rigid fork, you should opt for a "suspension-corrected' rigid fork to preserve the frame's normal geometry.
Sutherland's Handbook for Bicycle Mechanics by by Howard Sutherland, is the technical reference par excellence for bicycle mechanics. It is the source of much of the information included in this glossary, and much more. Every bicycle shop should have at least one copy of this indispensable reference work. It is available through bicycle distributors.
Swaging is the process of shaping metal by impact, particularly as making a thin part thicker. For instance, the heads on bicycle spokes are produced by "swaging" the end of the spoke wire. Swaging, unlike forging, does not usually involve heating the metal to a high temperature.
Cheaper cranks use swaging as a means of attaching the spider or chainwheel to the right crank.
Better-quality cranks are made with the right crank and spider a single forging or casting, with no joint to fail. Forged cranks are not only more durable, but the chainrings tend to run straighter, providing better shifting performance.
Swaged cranks were formerly common, but are now seen mainly on low-end bicycles. A swaged crank is an iffy proposition on a tandem, a fixed-gear bicycle, or a bicycle with a coaster brake, because applying force in both directions runs a substantial risk of loosening the chainwheel so it freewheels in both directions.
Swiss bottom bracket threading is the same diameter and pitch as French, but differs in that Swiss fixed cups are left (reverse) threaded, while French fixed cups, like the adjustable cups, are right threaded.
These shifters are mainly seen on Japanese "road " bikes from the 1982 model year. They use an "aero" mount where the shifters attach just above the top tube, instead of on the sides of it. Most of them used a special proprietary braze-on mount that isn't interchangeable with anything else.
These shifters are a bit problematical. Like other "friction " shifters, the lever friction is regulated by the bolt the lever pivots around. If you tighten that bolt a bit, the derailer will more or less stay in position. If you tighten it too much, it will be hard to move the lever. .
Unfortunately, these levers are a fundamentally flawed design. SunTour built in a special cam mechanism to make the front derailer move slightly to "trim " its position as you shifted the rear. This was a good idea -- it is a wonder that nobody else has taken it up -- but poorly executed.
The automatic "trimming" mechanism generally only works in one direction. Which direction that will be depends on the relative friction settings of the front and rear levers. Theoretically there's a particular balance point where it works right, but in practice this never works.
The sync, or "timing" chain on a tandem connects one bottom bracket to another. There is a synch chain for each stoker, so, for instance, a triplet has two synch chains.
Sync chains generally connect equal-sized chainwheels, so the mechanical advantage is 1:1. This is true for all sizes of sync chainwheels, as long as they are both the same size. Smaller sync chainwheels, however, put a greater stress on the sync chain, the frame, and the bottom bracket bearings, so it is a mistake to make them too small in an attempt to save weight. Typical sizes are in the range of 38 teeth and up.
It was Campagnolo's wish to make a system that would be compatible with its older derailers and other products, to provide an easy upgrade path for existing customers. This was a laudable goal, but turned out to be impractical.
The Synchro (and Synchro 2) down tube shift levers had replaceable, color-coded "indexing discs" with detent notches at different spacings. There were quite a few different indexing discs available for different freewheel models and spacings.
The problem that sank Synchro was cable travel. Campagnolo derailers had always used a very short cable travel from gear to gear. The shorter travel came with higher tension, and these two factors exacerbated issues of cable friction and stretch. As Shimano also discovered, a key to good indexing is long-travel, low-tension cable setups. Shimano also made a misstep with this: its original 1984 Dura-Ace S.I.S. system used a fairly short cable travel, requiring unusually-high precision in associated parts. When Shimano "trickled down" S.I.S. to the 600EX group in 1986, it went with a longer cable travel, which became the standard for the rest of the Shimano line. This led to a decade of incompatibility between Dura-Ace and the rest of the Shimano line, only resolved in 1997 when Dura-Ace went to 9-speed and lengthened the cable travel to match the rest of the line.
Currently, Campagnolo's shifters and derailers use an even longer cable travel than Shimano does.
Synchro derailers and shift levers are incompatible with anything else, and the Synchro system worked so poorly that it is not a good idea to try to set the system up on a bike you intend to actually ride.
