| rattrap | A colloquial term with two meanings. It can mean a luggage carrying platform which mounts over the wheel, or a style of pedal which has a metal cage. | Sheldon Brown |
| RDS | A MTBiking term, abbreviation for Rapid Deceleration Syndrome. Originally a military term for the very sudden illness that happens when the free-flight following a high-speed (involuntary) dismount is interrupted by something solid. | Bicyclesource.com |
| reaction arm | The arm which connects a coaster brake or other hub brake to the chain stay or fork blade. It is designed to prevent the axle and other non-rotating parts of the hub from turning under the stress of braking. The reaction arm may be attached to the stay or fork blade either by a metal strap, or by a braze-on. The "Pacman" braze-on allows the wheel to be removed without having to un-bolt the reaction arm from the frame. Some models of the Rohloff Speedhub use a reaction arm in place of anti-rotation washers to keep the hub's axle from rotating in the frame. (The gear range of the the Rohloff hub is so wide that simple anti-rotation washers would not be sufficient to withstand the axle torque in the extreme gears.) By pedalling backward about an eighth-turn of the pedals, a coaster brake can stop a bicycle's rear wheel easily. The torque developed at the hub is tremendous. Normally, that torque would spin the coaster brake's axle within the dropouts - not a desirable condition. Therefore, to counteract the force, a steel arm comes out of the left side of the coaster brake, and is fastened to the chainstay a few inches away - The reaction arm. | Sheldon Brown |
| rear admiral | A term for the stoker of a two-person tandem. | Sheldon Brown |
| rear centre | The distance from the bottom bracket to the rear axle. | Sheldon Brown |
| rear triangle | The triangle formed by the chain stays, seat stays, and seat tube | Bicyclesource.com |
| rebound | The speed at which suspension returns to it’s “at rest” position after compression. If your rebound is too fast then your suspension snaps back into position and it feel like you are riding a pogo stick; if your rebound is too slow then multiple impacts in rapid succession will cause you suspension to “bottom out.” | Sheldon Brown |
| recessed brake mounting | Calliper brakes have a centre bolt 6 mm or 1/4" in diameter, which fits through matching holes in the fork crown and the brake bridge of the frame. Traditionally, these bolts have been long enough to protrude all the way through, to be secured by a normal hex nut, and associated washers. Most newer good-quality bicycles that use calliper brakes use recessed mounting to save weight and for a more elegant appearance. Callipers intended for recessed mounting have much shorter centre bolts, which do not extend all the way through the crown/bridge. Frames/forks designed for recessed mounting have stepped holes...6 mm in front, substantially larger at the back. Instead of a conventional hex nut that takes a 10 mm wrench, a cylindrical nut is used, which is broached for a 5 mm allen wrench. Because the trend toward recessed mounting and toward short reach callipers happened simultaneously, most short-reach callipers come set up for recessed mounting. Medium- and long-reach callipers usually come with longer centrebolts for conventional mounting. | Sheldon Brown |
| Record ™ | The benchmark in Campagnolo pro-riding gruppo, incorporating the best materials, technology and technical solutions in an incomparably aesthetically pleasing crownjewel. | Campagnolo.com |
| recumbent | Recumbent bicycles are more aerodynamic than conventional "upright" bicycles, but tend to be more complicated.They are very comfortable & well adapted for long-distance riding, and fall into several classes which are known by arcane abbreviations: L.W.B. (Long Wheel Base) recumbents have the front wheel located in front of the "bottom bracket" which have straight, efficient chain runs but poor weight distribution (too little on the front wheel), and general unwieldiness. C.L.W.B. (Compact Long Wheel Base) recumbents are a variation which usually uses smaller wheels. S.W.B. (Short Wheel Base) recumbents have the front wheel behind the bottom bracket. are more manoeuvrable. SWBs generally have to run the chain over an idler pulley or two, which causes a loss in efficiency. A.S.S. (Above Seat Steering) recumbents have tall handlebars with grips located in front of the rider's shoulders. U.S.S. (Under Seat Steering) recumbents' handlebars located below the seat, so the rider's arms hang down at his or her sides - a very comfortable position which makes for easier dis/mounting. | Sheldon Brown |
| reel in | Action where the peloton overtakes a breakaway attempt. | The Complete Book of Bicycling |
| reflector | Reflectors are supplied with most bicycles with the intent of making the bicycle visible at night when illuminated by the headlights of another vehicle. | Sheldon Brown |
| refor | A MTBiking term. Ree'four'ing - to ride about with reckless or vandalous disregard for the local ecology. Stems from the practice of using jeeps to scream around reforestation areas leaving a wake of destruction in their path. "Hmmm - we just came back from reforing around the elementry school's front lawn." | Bicyclesource.com |
| Regina Siefel | A MTBiking term. She won the DH world cup twice. Suffers from same curse as Furtado; she's never won a world championship. Lives with husband and kids next to the Zugspitze, Germany's highest mountain. | Bicyclesource.com |
| relay | A MTBiking term. A specific form of a time trial, in which a team of competitors cover great distances (riding almost around the clock). | Bicyclesource.com |
| remorqueur | A French cycling term. Literally, a "tow truck", and used to refer to a rider who rides in the front to protect his team mates from the wind. | University of Toronto |
| retainer | A retainer is a clip, usually sheet-metal or plastic, that holds and separates the bearing balls in a ball bearing. The advantages of retainers are ease of assembly, and economy because the manufacturer can get by with fewer balls, if they are spaced apart by a retainer. Retainers are a good thing for headsets, and one-piece cranks, due to the ease of assembly issue. They are generally not so good for other bicycle bearings. Conventional bottom brackets with loose balls can hold 11 1/4" balls per side. High quality retainer sets also have 11 balls. Cheaper retainers will only have 9 or even as few as 7 balls, and should not be used. | Sheldon Brown |
| retro-grouch | A MTBiking term. A rider who prefers an old bike with old components and isn't fond of new, high-tech equipment. | Bicyclesource.com |
| Reynolds ® | Currently known as TI/Reynolds, is an old and very highly regarded maker of bicycle tubing. They pioneered the techniques of making butted tubing around the turn of the century, and their 531 (say "five, three, one") manganese-molybdenum alloy tubing was the standard of excellence for many decades. Newer formulations from Reynolds include 753 and 853. | Sheldon Brown |
| RF+ | An acronym for "RapidFire Plus ®" is the successor to RapidFire, using a thumb button to select a larger chainring and an index-finger "trigger" to select a smaller sprocket, having solved the ergonomic problems of the original RapidFire. It remains Shimano's flagship shifting system for upright handlebars. | Shimano.com |
| rhoid buffing | A MTBiking term. Going down a hill so steep that your butt touches the rear wheel. | Bicyclesource.com |
| Ride On! | A MTBiking term. A parting phrase used by riders without much to say. | Bicyclesource.com |
| riding in tow | See 'drafting'. | The Complete Book of Bicycling |
| riding the pegs | A MTBiking term. Standing on the pedals through rough terrain. | Bicyclesource.com |
| rigid | A frame or fork which does not have any built in mechanical suspension system. Conventional forks actually are designed to flex slightly over bumps, but they are still called "rigid" forks as compared with true suspension forks.It also refers to a bike with no suspension. | Sheldon Brown |
| rim | The outer metal hoop of a bicycle wheel. The rim does not include the spokes, nor the hub. | Sheldon Brown |
| rim cut | A pinch flat, or the damage suffered by the tyre sidewall from similar causes. | Sheldon Brown |
| rim strip | A strip of rubber, plastic or cloth that protects the inner tube in a wheel from being punctured by wearing against the tops of the spoke nipples or the rim. | Sheldon Brown |
| rise | In an upright handlebar, the "rise" is the vertical distance from the low point of the bar (the middle) and the high points (typically the grip area.) | Sheldon Brown |
| riser bar | A MTBiking term. An offset handle-bar for mountain bikes where the grips are higher from the ground than the center section giving you more control and comfort. | Shimano.com |
| rivet | A rivet is a cylindrical fastener that fits through a tight-fitting hole. The end of the rivet is then hammered or "peened" over so that it spreads out like a mushroom, so that the rivet will stay in place. Generally, rivets are one-time fasteners for parts that are not expected to be disassembled for servicing. Rivets are commonly used to assemble derailleurs, fenders and saddles together. They are also used to assemble low-quality pedals and cranks/chainweels. The links of a bicycle chain are held together by rivets which, in most cases only have a slight thickening at the ends, rather than a seriously spread head. This allows chain links to be disassembled by partially removing the rivet, then driving the rivet back in with a chain tool. | Sheldon Brown |
| road bicycle | In the broadest sense, this would refer to any bicycle designed to be ridden primarily on pavement. Usually, the term "road bicycle" is used to refer to a sport bicycle with drop handlebars and narrow tyres. Sometimes the term is used in an even more restrictive sense, to apply to a road racing bicycle. | Sheldon Brown |
| road racing | In one sense, road racing is any racing that is done on roads, but the more usual sense is that of a mass-start race from one place to another, or possibly a loop course with long laps (as opposed to a criterium.) Since road races tend to be longer than criteriums, and the packs tend to be smaller and less dense than those in criteriums, bicycles designed for road racing tend to favour comfort more than criterium machines do, but to be less manoeuvrable. They may have lower bottom brackets, since there is less need to pedal through corners in a road race than there is in a short-course criterium. | Sheldon Brown |
| road rash | A MTBiking term. Large abrasions on a rider's legs and body caused by a crash, particularly on asphalt. | Bicyclesource.com |
| roadie | A MTBiking term. A white socked rider who considers trails to be for the weak and feeble. | Bicyclesource.com |
| roadster | A traditional type of utility bicycle, sometimes known as a "postman's bike". These usually have 37-635 (28 x 1 1/2) wheels, rod brakes, a chaincase, slack angles. Most of them are black. This is the predominant type of bicycle in Asia, the Netherlands (although Dutch roadsters are more likely to have rod-operated drum brakes). | Sheldon Brown |
| rock garden | A MTBiking term. A section of the trail that is completely covered with grapefruit (baby head) size to basketball sized rocks. | Bicyclesource.com |
| rock-ectomy | A MTBiking term. Removing rocks, dirt, gravel from one's person after a yard sale. "Some betty stopped by and performed a rock-ectomy on my knee after the wreck, I think she digs my scene." | Bicyclesource.com |
| rocket fuel | A MTBiking term. Mandatory pre-ride coffee. | Bicyclesource.com |
| rod brake | Also ' Roller-lever brake'. Some rod brakes use the rods to operate a drum brake, which is popular in the Netherlands. Most rod brakes use a "stirrup" which holds brake shoes that pull against the inner circumference of the rim. These are usually used with Westwood or Raleigh pattern rims, which have a ridge where the spokes attach, so there is no risk of snagging a spoke nipple with the brake shoes. | Sheldon Brown |
| Rohloff ® | Rohloff is a German company, a maker of high quality chains and tools, but best known for the Rohloff Speedhub, a 14-speed internal gear hub. The Rohloff Speedhub has an unusually wide gear range. | Sheldon Brown |
| Rollback | A BMX term. Whilst riding fakie, spin the bike 180degrees on the backwheel to ride 'normally'. | Wikipedia.com |
| roller bearing | A bearing that uses cylindrical or conical rollers instead of balls. The major bicycle application of roller bearings is in some headsets. Roller bearing headsets are very long lasting, due to the greater contact surface area as opposed to ball bearings. Current units, however do not turn as freely as ball bearing headsets. This is due to the use of cylindrical rollers, rather than conical rollers. Cylindrical rollers do not naturally roll in a circle, but in a straight line. | Sheldon Brown |
| Roller brake ® | A Shimano trademark for a variant form of hand-operated drum brake. It uses a ring of rollers pushed outward by a cam to engage the brake shoe with the drum. The cam is operated by a cable from a hand lever. | Sheldon Brown |
| roller cam brake | A type of brake which uses a triangular cam with see-saw like arms, pivoted in the middle on cantilever-type studs. The cam is pulled by the cable - being attached to the narrow end - with its sloping sides pushing outward on rollers attached to the upper end of the brake arms. Roller-cam brakes permit the use of variable ratios (the sides of the cam curve ) to make the pads travel in toward the rim fast, slowing them down as they engage. This gives more mechanical advantage in the actual braking range while allowing the shoes to back off farther from the rim. Rollercams have the advantage of not protruding past the sides of the frame, which made them popular when there was a fad for placing the rear brake under the chainstays. | Sheldon Brown |
| roller / roller chain | Standard bicycle chain has rollers that smooth the engagement of the chain with the sprockets, as opposed to a "block" chain. It is a floating, inner cylinder within a chain's links that meshes the chain's links with individual cogs. | Sheldon Brown & Johan Bornman |
| roller clutch | A roller clutch (or "silent clutch" in Shimano terminology) is a type of freewheel ratchet mechanism that uses cams and rollers instead of pawls. In addition to eliminating the annoying "tick-tick-tick" of a pawl-type freewheel, a roller clutch has less slop when drive force is applied to it...drive begins as soon as forward motion of the pedals starts, unlike a pawl-type freewheel which only drives once it has rotated far enough to let the pawls engage the notches of the ratchet ring. | Sheldon Brown |
| roller lever | A hand-operated brake that uses solid rods and pivots as a linkage from the handlebar to the brake unit. Roller-lever brakes are harder to work on than brakes operated by Bowden cables, but they are more reliable than cables, especially on bicycles which are subject to neglect and abuse. They are commonly found on roadsters. | Sheldon Brown |
| rollers | A treadmill-like device for riding a bicycle indoors. Consists of a framework with 3 rollers. The front wheel rests on top of one of the rollers, and the rear wheel sits between two of them. The front roller is connected to one of the rear rollers, so that as the rear wheel turns its rollers, the belt makes the front roller turn with them. This allows the bicycle to be "steered" within the length of the rollers, and allows the bicycle to be balanced as if it were being ridden on the road. Compared with a stationary trainer, rollers have the advantage of forcing one to ride in a very smooth manner, and generally improve form and smoothness on the bike. For most riders, however, a stationary trainer allows a higher intensity of riding, since it requires no mental effort to stay balanced. Mastering roller riding is tricky. It is helpful to start out with the rollers in a doorway, so that one can lean against the door frame to prevent a fall. It is also useful to have a full-length mirror straight ahead, so that you can observe your form. Don't look down! | Sheldon Brown |
| rolling a tyre | A situation in which sew-up (tubular) tyre roll off the edge of the rim while cornering. (These tyres are glued to rims that are not as concave on their outer surface as conventional rims. Rolling a tyre is usually caused by improper gluing, but can happen in unusual cornering situations, such as hitting a stone or edge in the pavement while cornering. With properly glued sew-up tyres, rolling a tyre is very rare.) | Sheldon Brown |
| rolling enclosure | A type of traffic control where escort vehicles form a caravan leading and following a group of racers. The enclosure sets aside a moving part of the roadway in the direction of the race for exclusive use of bicyclists. Racers inside the enclosure are not required to follow the normal rules of the road. Racers are not allowed to cross the center line unless the entire road is traffic controlled. A rolling enclosure is the typical traffic control used to run a road race. | Bicyclesource.com |
| rolling resistance | If undeformable perfectly circular wheels could roll on an equally undeformable, smooth & perfectly level surface, there would be no rolling resistance at the contact point. But, to compensate for the inevitable unevenness, the wheel is equipped with pneumatic tyres acting as a shockabsorber.The friction caused by the flexing of the tyre and tube as it deforms under load over the unevenness constitutes 'rolling resistance'. For a given tyre, rolling resistance will vary considerably with the inflation pressure ( either too stiff or too low), but as a rule of thumb for onroad travel, the higher the pressure, the lower the rolling resistance. Offroad is a bit more intricate, as there is more unevenness to be dealt with. | Sheldon Brown |
| rolling road closure | A type of traffic control in which the entire road is closed to other traffic as the race passes any given point. The road reopens after the race passes. | |
| rollout | The distance a bicycle travels in one complete revolution of the cranks; also referred to as 'development'. | Sheldon Brown |
| ROMP | An acronym for Responsible Organized Mountain Pedallers, a Silicon Valley organization teaching mountain biking skills, organizing rides and active in trail politics. | Bicyclesource.com |
| Ronde van Vlaanderen | The Belgian 'Tour of Flanders', 1st held in 1913, raced in early April - a monument of cycling. | Wikipedia.com |
| rookie mark | Chain grease on a rider's pant leg. "Give that guy extra points for his rookie mark. It's even on the wrong leg!" | Bicyclesource.com |
| roost | A MTBiking term. To go fast or accelerate quickly. Or, to stop suddenly. | Bicyclesource.com |
| rooster trail | A MTBiking term. A spray of water flung off the back wheel as the bicycle rolls through water. Particularly pronounced on bikes without fenders. | Bicyclesource.com |
| rotating weight | Weight that is rotating while the bike is moving, particularly referring to the wheels. Weight near the perimeter of a wheel has about twice the stored energy of non-rotating weight on a bicycle when moving. Rotation of cranks, wheel hubs, and other parts are of little significance because the radius and speed of rotation are small. Rotating weight resists acceleration (or deceleration), so lighter wheel rims, spoke nipples, and tyres allow slightly quicker acceleration. There is no significant difference between rotating and non-rotating weight when at steady speeds, or for hill climbing. | Sheldon Brown |
| Rothaus Riderman | A fairly easy road cycling event for all / non pro's held in Bad Durrheijm (in the Black Forest) during September. A 6lap cirterium (25kim-150km) with full road closure and an individual time trial complimented by an awaerd ceremony, Pasta party and entertainment. Forms part of the UCI Golden Bike Series. | Wikipedia.com |
| rotor | A mechanism used on freestyle bicycles to route the rear brake cable through a bearing assembly which surrounds the handlebar stem. This allows the handlebars and fork to revolve indefinitely without fouling the rear brake cable. See also 'Potts modification'. Probably the best rotor currently available is the Odyssey Gyro ® | Sheldon Brown |
| Rover | The Rover safety bicycle was an improvement (circa 1892's) on the boneshaker - bicycles, with peumatic tyres and a diamond frame remarkably similar to the modern bicycle. The "safety"concept came from the redundancy of / departure from the Penny-Farthing's large front wheel (and the injuries caused by it.) | Wikipedia.com |
| RPM | R.P.M. Revolutions Per Minute, a measure of speed of rotation. In bicycling, this is most often used in discussions of pedalling cadence. | Sheldon Brown |
| rude drop-off | A MTBiking term. A sudden drop on the trail of two feet or more. | Bicyclesource.com |
| Sachs ® | A European conglomerate that bought up many of the formerly independent French parts makers, including Atom/Maillard/Normandy (hubs, pedals, freewheels) Hurét (derailleurs) and Sedis (chains.) 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, and this is likely to change. Sachs also made multi-speed internal-geared hubs in 3-, 5-, 7- and 12-speed versions. Their "3 x 7" hub is a hybrid system, a 3-speed internal hub that takes a 7-sprocket cassette, providing 21 speeds with only one chainwheel. They formerly also made kick-back hubs and a "2 x 6" hybrid hub. The one clear area of domination for Sachs is their chains, which are generally acknowledged to be the finest available. The official Sachs website is not very informative. More up-to-date information is on the SRAM site. Sachs was purchased by SRAM, so most of the products formerly called "Sachs" are now called "SRAM." | Sheldon Brown |
| saddle | 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 moulds itself to fit the particular anatomical shape of its rider. | Sheldon Brown |
| SAE | 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 referred to as SAE sizes | Sheldon Brown |
| safety bicycle | In 1885 John Kemp Starley launched the Rover Safety Bicycle (so-called because the rider was seated much lower down and much further behind the front wheel contact point) and over the next fifteen years or so, the penny farthing vanished.These bicycles had the modern placing of the crank axle and featured a cross-frame tension structure. With two wheels of equal size and a roller chain geared transmission, the safety bicycle was the grandfather of today's machines. The high-wheeler lives on in spirit in the ‘gear inch units’ used to describe gear ratios, but the shape of the Rover Safety and its development of the traingle based diamond-framed bicycle has come to dominate the perception of what a bicycle looks like. Dunlop's pneumatic tyre and the chain drive made the safety bicyle possible. | Wikipedia.com |
| sag | The weight-bearing amount of suspension compression from a rider having mounted the bike. | Sheldon Brown |
| sag station | A location along the course of a long mass-participation recreational ride providing mechanical and/or medical assistance to riders in need. Volunteers at the SAG station may also dispatch SAG wagons to assist riders stranded along the course. A SAG station may also function as a food stop. | Sheldon Brown |
| sag wagon | Sag Wagon. A car or truck that picks up or otherwise assists riders who have had to stop riding, either 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." | Sheldon Brown |
| Santana ® | Santana is the worlds leading manufacturer of tandems. Starting in the 1970s under the leadership of Bill McReady, Santana virtually re-invented the tandem, which had been in decline since the second world war. | Sheldon Brown |
| schmooz | A MTBiking term. The act of reaching a trail head and not riding. What is done when one really can't stand the thought of starting a ride. Talking. Bullshitting. | Bicyclesource.com |
| schwag | A MTBiking term. 1) Terrible trail conditions. 2) Free stuff. | Bicyclesource.com |
| scorcher | A fast, reckless cyclist who scares horses and old folks. This was a term current in the late 19th century. In the early 1990s, Ibis made a small run of retro-style fixed-gear bicycles for street use, which they called the "Scorcher." This was picked up by the media and caused a brief boom. 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. | Sheldon Brown |
| scratch | Last riders to depart in a handicap race. Also referred to as the "scratch bunch" or "scratchies". | Sheldon Brown |
| scream | A MTBiking term. 1) n. a real biker's dream ride. 2) A long, straight, and deceptively steep hill 3) To bomb so fast one can't pedal fast enough to make a difference. | Bicyclesource.com |
| screamer | A MTBiking term. A very, very high dropoff. "I was trying so hard to keep my eyes away from the ledge back there. What a screamer!" | Bicyclesource.com |
| sealed bearings | A "sealed" bearing is one that 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 dust cap. | Sheldon Brown |
| seamless | 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. | Sheldon Brown |
| seat cluster | The junction between the seat tube, the top tube and the seat stays of a frame. The seat cluster usually also incorporates the seat-post binder bolt that clamps the seat tube or seat lug tight around the seat post to secure it. | Sheldon Brown |
| seat lug | The lug at the seat cluster of a lugged frame. | Sheldon Brown |
| seat pillar | British term for seat post | Sheldon Brown |
| seat pin | British term for seat post, particularly the simple "pipe" type seat post which uses a separate saddle clamp. | Sheldon Brown |
| seat post | The tubular support that holds the saddle which 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. | Sheldon Brown |
| seat post bolt | The binder bolt that secures the seatpost in the frame. It may be a conventional bolt with a nut, or an Allen bolt, or a quick release. | Sheldon Brown |
| seat sandwich | An adaptor to allow a saddle with four frame rails to mount onto a standard one-bolt "microadjust" type seat post. This consists of a grooved brass plate that 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. | Sheldon Brown |
| seat stays | The thin frame tubes that run from the rear fork ends up to the seat cluster | Sheldon Brown |
| seat tube | The frame tube running from the bottom bracket up to the seat cluster. | Sheldon Brown |
| Seatgrab | A BMX term. Grabbing the seat with one (or both) hand/s. | Wikipedia.com |
| seating | The way a tyre is mounted on a rim. i) It is very possible to inflate a tyre that is not seated properly, and have an edge blow off the rim, wrecking the inner tube. This is called a blowout. When inflating a tyre, put just enough air in it at first to take its shape. Look at both sides all the way around, and make sure it is seated properly. Inflate it to full pressure in stages, examining the tyre for seating problems several times during the process. If a bulge starts to appear, let the air out, and reposition. ii) Another seating problem is the opposite of bulging - flat spots, which result in a bumpy ride. A flat spot often indicates a bulge elsewhere around the tyre. | Sheldon Brown |
| Selecta ® | Selecta was an early Shimano ® attempt at a splined crank/bottom bracket system, dating from the late '70s or early '80s. The spline pattern was chosen to permit the spindle to fit through a Front-Freewheel bearing set, which wouldn't permit a standard sized square tapered bottom bracket spindle to fit through the front freewheel bearing assembly. These turned out to be rather unreliable, due to the small diameter of the splines, and Shimano abandoned the system. They did continue to supply spare parts for many years thereafter, but these are no longer available. | Sheldon Brown |
| self energising brakes | 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. | Sheldon Brown |
| selle | 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. | Sheldon Brown |
| semi- tangent | The most common spoke pattern, used on the vast majority of bicycles. | Sheldon Brown |
| semi-loop | A MTBiking term. A loop trip with a section of out and back attached. | Bicyclesource.com |
| Servo Wave ™ | Shimano speak - componentry. | Sheldon Brown |
| set screw | 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. Rings with setscrews are used to hold some cartridge bearing hubs and bottom bracket assemblies together. 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. | Sheldon Brown |
| sideplate/s | Flat, camphered pairs of metal plates (within the chain assembly) with holes for accommodating the pins and in the case of the inner plates, with a collar for supporting the roller. Both inner & outer plates. | Johan Bornman |
| sprocket | A flat, round gear with portruding cogs / teeth. See "driven sprocket "/ "driving sprocket" / "chainring" / "cluster" / "cassettte". | Johan Bornman |
| seta | Italian for "silk". The finest tubular tyres are made of silk fabric. | Sheldon Brown |
Cycling Terms 
