As time went on, the Bicycle Glossary has grown, and many of the pages became inconveniently large.I have split the larger pages into smaller ones, but I realize that there may be external links pointing to the older pages. For this reason, I have maintained copies of the older pages at the same location.
This is one of the older pages, and the newer pages that were derived from it are liable to be more complete and up to date, so please follow the links below to the current version. Sorry for any inconvenience.
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Sheldon Brown
For an explanation of this design, see my wheelbuilding article.
With half-step gearing, the larger shifts are made with the rear derailer, and the front is for fine tuning. This allows an 8- or 10-speed set up to have a reasonable range with fairly close spacing of the gears. One downside of half-step is that it uses all possible combinations, including those that run the chain at a fairly severe angle. This is not a big deal in an 8-speed rig, but is kind of marginal for 10-speeds. Another serious disadvantage is that every other shift in the normal sequence is a double shift (front and rear derailers simultaneously).
Half-step gearing is most suitable for riding in flat terrain, where shifting is rare. For bicycles with few speeds, it does allow finer gradations to get as close to the "ideal" gear for the particular wind conditions as possible.
Modern shift patterns use larger jumps on the chainwheels to select general ranges of gears, and fairly closely-spaced 7-or-more-speed clusters for the fine tuning. This greatly simplifies the shifting pattern, allowing constant adjustment to different grades in rolling terrain, with only occasional need for double shift.
Conventional handlebars are divided broadly into two styles: "drop" and "upright"
| Handlebar dimensions | ||||
|---|---|---|---|---|
| Stem Clamp Size | Grip Area Size | Application | ||
| 22.2 mm | 7/8" | 22.2 mm | 7/8" | Steel bars. Mainly BMX, older Mountain bike bars. |
| 23.8 mm | 15/16" | 22.2 mm | 7/8" | Obsolete British size for steel handlebars, common on older 3-speeds. This size was also used for older British steel drop bars. |
| 25 mm | 23.5 mm | Obsolete French size. | ||
| 25.4 mm | 1" | 22.2 mm | 7/8" | Standard I.S.O. size, used on the vast majority of newer bicycles with upright handlebars. This size was formerly common for steel drop bars. |
| 25.4 mm | 1" | 23.8 mm | 15/16" | Standard I.S.O. size, used on most bicycles with drop handlebars. Also used on older British aluminium upright handlebars. |
| 25.8 mm | 23.8 mm | 15/16" | 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 | 23.8 mm | 15/16" | 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 | 23.8 mm | 15/16" | Older Cinelli and Cinelli copies. Cinelli changed over to 26.0 mm in 1998. | |
| 27 mm | 23.8 mm | 15/16" | Titan (obsolete). | |
| 31.8 mm | 1 1/4" | 23.8 mm | 15/16" | Road oversized. |
Sometimes incorrectly referred to as "handlebar ribbon." This mistake results from a translation error. (in French and Italian, there is no distinction between "ribbon" and "tape.")
A conventional threaded headset consists of four races plus associated parts:
The adjustable race is secured by either a:
This type of headset must be used with a special handlebar stem that clamps on to the outside of the steerer, either with one or more binder bolts, or other means. The stem is further secured by a plastic or metal cap which is bolted to the star nut.
To adjust an "Aheadset"-type headset, the stem binder must be loosened, then the bolt that runs through the cap to the starnut is tightened, usually with a 5 mm Allen wrench. This presses the stem down against the tapered bushing that fits inside the adjustable cup. and takes up the slack in the system. The stem is then aligned with the front wheel and tightened with its binder bolts. (Once the stem binder bolts have been tightened, the adjusting bolt that goes to the star nut is under no significant stress, and may even be removed.)
The upper collar has a gap at one point, with a binder bolt to squeeze the gap together. (This upper collar may also include a cable stop for the front brake, if the bicycle has a rigid fork and conventional cantilever brakes.)
The handlebar stem is clamped tightly to the steerer, preventing the upper collar from moving upward. As the upper collar is compressed by the binder bolt it squeezes lower collar downward, taking up any slack in the headset bearings.
The Ge Force is the only threadless headset which doesn't use the handlebar stem as part of the adjustment. These headsets may be used with any stem, either external clamping or internal expander/wedge type.
| Threaded Headsets | |||||
|---|---|---|---|---|---|
| Size Steerer O.D. | Stem diameter Steerer I.D. | Crown race Inside diameter | Frame Cup Outside Diameter | Threads Per inch | Notes |
| BMX/ O.P.C. bikes | .833" (21.15 mm) | 26.4 mm | 32.7 mm | 24 | Used mainly on bicycles with one-piece cranks, also some early mountain bikes. |
| French 25 mm | 22 mm | 26.5 mm, 27.0 mm | 30.2 mm | 25.4 (1 mm) | Obsolete. French steerers usually have a flat filed on the back, rather than a grooved keyway as with other threaded systems. |
| 1" ISO Standard (25.4 mm) | 7/8"(22.2 mm) | 26.4 mm | 30.2 mm | 24 | This is the standard 1" size. |
| 1" Italian (25.4 mm) | 7/8"(22.2 mm) | 26.5 mm, 27.0 mm | 30.2 mm | 24 | Obsolete. Threads are cut at 55 degrees, but ISO or J.I.S. headsets can be used. |
| 1" J.I.S. (25.4 mm) | 7/8"(22.2 mm) | 27.0 mm | 30.0 mm | 24 | Older or lower-quality bicycles from Asia |
| 1" Raleigh (25.4 mm) | 7/8"(22.2 mm) | 26.4 mm | 30.2 mm | 26 | Proprietary size used on Raleighs made in Nottingham, England |
| Austrian (26 mm) | 22 mm | 26.7 mm | 30.8 mm | 25.4 (1 mm) | Higher quality Austrian bikes use English/ISO |
| French Tandem 28 mm | 22 mm | 25.4 (1 mm) | Obsolete and rare. | ||
| 1 1/8" (28.6 mm) | 1" (25.4 mm) | 30.0 mm | 34.0 mm | 26 | "Oversized" (This size is more often used for threadless systems.) |
| 1 1/4" (31.8 mm) | 1 1/8" (28.6 mm) | 33.0 mm | 37.0 mm | 26 | Mainly used on tandems |
| Size/Stem diameter | Steerer O.D. Crown race | Inside diameter Frame Cup | Outside Diameter Notes
| BMX/ | 26.4 mm | 32.7 mm | Used mainly on bicycles with one-piece cranks.
| 1" ISO Standard (25.4 mm) | 26.4 mm | 30.2 mm | This is the standard 1" size.
| 1 1/8" (28.6 mm) | 30.0 mm | 34.0 mm | Most newer mountain bikes use this size.
| 1 1/4" (31.8 mm) | 33.0 mm | 37.0 mm | Mainly used on tandems
| 1.5"
(38.1 mm) | 39.8 mm | 49.6 mm | Proposed OnePointFive standard
for downhill and freeride applications.
| | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
If you want to replace one headset with another, you must take into account the stack height of the new headset.
Both hub flanges were 1mm farther to the left than those of a normal hub, causing increased dish in the rear wheel, and persistent spoke breaage problems. Many loyal Helicomatic fans tout the ease with which the cassette may be removed for spoke replacement as a great virtue, but if the hub were better designed, it wouldn't break so many spokes!
These hubs were prone to bearing problems as well. Due to clearance requirements, they couldn't fit the normal 9 1/4" bearing balls, so they used 13 5/32 balls on the right side. These didn't hold up well, and replacement cones are no longer available to fit these hubs.
Hellenic stays were introduced by (and named for) the British frame builder Fred Hellens in 1923, and have been used off-and-on since by frame builders who wish to make their frames visually distinctive. It is of no practical value, and often causes un-necessary complication to brake cable routing, luggage rack attachment and installation of frame pumps. It is also slightly heavier than normal frame construction.
Recent users of this design include GT, Huffy and Nashbar.
He also did a lot of pioneering work on suspension designs for bicycles, and deveoped a bicycle seat that was based on an upside-down dropped handlebar with furniture webbing wrapped between the two straight sections.
He was also known for roller demonstrations where he would perform a strip-tease while riding on the rollers. A very cool guy.
High gears are for going fast, when the terrain permits. The rider must push much harder on the pedals in a high gear, so high gears are not suitable for lower-speed riding, due to the great strain that hard, slow pedaling puts on the joints.
Before the use of chain drive, bicycles had direct drive. The cranks were directly attached to the hub of the drive wheel. The larger the wheel, the farther the bicycle would move with each turn of the pedals. The diameter of the drive wheel determined the gear of the bicycle. The larger the wheel, the higher the gear.
With a chain-driven "safety" bicycle, you can have any gear you want by selecting appropriate sprockets. With a high-wheel bicycle, the limiting factor is how long your legs are, because you can only pedal a wheel that is small enough for your legs to straddle and reach the pedals throughout the pedal revolution.
The safety bike was first introduced on a commercial scale in 1885, and by 1893 high-wheelers were out of production.
With the advent of index shifting, greater precision was required, particularly for handlebar-mounted shift controls. For this application, "compressionless" housing is now used. This differs from traditional housing in that the wire part consists of a bundle of parallel wires, running more-or-less parallel to the cable. This reduces the tendency of the housing to change effective length when it flexes as the handlebars turn. This type of housing should not be used for brake cables, as it is likely to rupture under the higher loads involved in braking.
| Threaded Freewheel | Threaded Hub | Cassette Hub | Cassette Cluster |
|---|
Hub brakes activated by back-pedaling are called coaster brakes ("back-pedal brakes" in British usage.) Hand-operated hub brakes include disc brakes, drum brakes, and Rollerbrake ®s ®.
Hub brakes have the advantage of being weather proof, so they work as well in the rain as when they are dry.
Hub brakes are commonly fitted as drag brakes on tandems to avoid the risk of overheating the rims and blowing out tires. See my article on Tandem Brakes.
Disadvantages of hub brakes include greater weight, greater stress on the spokes, and increased difficulty in removing/re-installing the wheel.
Their best-known model was the "Alvit", introduced around 1960. The Alvit was the first inexpensive parallelogram-type derailer, and hundreds of thousands of them were sold through the mid 1970s. Most Schwinn Varsities used this model. The Alvit was a very sturdy unit, well made and reliable. Its parallelogram was pivoted on bolts that could be adjusted, unlike the rivets used in most derailers. The orientation of the parallelogram permitted the jockey pulley to track the cluster more closely than most derailers of its time. Unfortunately, the Alvit had a very strong return spring, which caused cable stretch to be excessive, degrading shifting performance. The strong spring also tended to lead to rapid wear and failure of shift cables.
Another famous Hurét model was the "Jubilee." The Jubilee was expensive and lovely, and has the distinction of being the lightest rear derailer ever made. It is much sought after by collectors and weight weenies.
The Hurét "DuoPar" touring derailer had two parallelograms (hence the name.) The extra parallelogram was used to move the jockey pulley up and down, permitting the DuoPar to handle a wider gear range than any other rear derailer before or since. The original DuoPar was quite expensive, and featured titanium parts. A later, less-expensive version, the Eco DuoPar was also available for a while.
In the 1980s, Huret was absorbed by Sachs, and Sachs, in turn was taken over by SRAM.
Hybrids usually come with 622 mm (700c) wheels like road/touring bikes, but with wider tires than are normally supplied for touring. Most hybrid bicycles, unfortunately, come with tires that are designed for looks rather than for function. These are typically knobbies 35-40 mm wide. These tires are not good for much. Knobby tires are good for dealing with soft sand and mud, but hybrid tires are too narrow for these conditions--if you plan on riding through soft sand and mud, you really should buy a mountain bike. When ridden on firm surfaces, these tires are noisy and slow, and can cause an irritating buzz as they roll. They also corner poorly on pavement.
Many hyrids, unfortunately, also take from the mountain bike side of the family, a high bottom bracket. High bottom brackets make sense for mountain bikes, which are intended for jumping over logs and threading through narrow single track. Since hybrid bikes are generally unsuited for this sort or riding, the awkwardness of mounting and dismounting with a high bottom bracket outweigh any possible advantage. This is particularly the case since hybrids are often used for urban cycling, where stop-and-go is the norm.
Hybrid gearing is no longer limited to the do-it-yourselfer, since the Sachs 3x7 hub has become generally available. This is a 3-speed planetary-geared hub which is designed to accept a Shimano-type 7-speed cassette.
Hybrid gearing provides the close spacing with a wider range of gears than can normally be obtained with a simple derailer system. It is also particularly well suited to bicycles with smaller than usual drive wheels, because the high range(s) of the internal gear eliminate the need for unusually large chainwheels to compensate for the small wheels.
Fortunately for cyclists, this cannot happen to a bicycle; they don't go fast enough, nor have a large enough contact patch, nor do the tires run at a low enough pressure to make hydroplaning possible.
Even with automobiles, actual hydroplaning is very rare. It is a much more real problem for aircraft landing on wet runways. The aviation industry has studied this problem very carefully, and has come up with a general guidline as to when hydroplaning is a risk. The formula used in the aviation industry is:
| Tire Pressure | Speed Miles per hour | Speed Kilometers per hour | |
|---|---|---|---|
| P.S.I. | Bars | ||
| 120 | 8.3 | 113 | 183 |
| 100 | 6.9 | 104 | 167 |
| 80 | 5.5 | 93 | 149 |
| 60 | 4.1 | 80 | 129 |
| 40 | 2.8 | 66 | 105 |
It consisted of a fitting to engage the lock ring, with a thin arm. The arm is bent and padded at the end, so that it will bump up against the frame's chainstay.
To use a Hypercracker, you remove the wheel from the frame, install the Hypercracker into the lockring, then put the wheel back in the bike. When you turn the pedals forward, the Hypercracker's arm bumps into the frame, and the cassette turns while the lockring is held immobile by the Hypercracker.
The Hypercracker is the only single tool that will remove a cassette lockring--normally, you need a lock ring tool and a chain whip. Since the Hypercracker used the bicycle's drive train as a chain whip, it was particularly handy for the touring cyclist, because it was a small, easily portable tool. Unfortunately, these are no longer in production.
Due to clearance problems, the cutaway between the splines on 11-tooth sprockets only goes halfway through the sprocket. The matching splines on HyperDrive-C bodies don't go all the way to the outer end of the body.
More information on Hyperglide cassettes is available in a separate article on this site.
Hyperglide requires that the teeth of adjacent sprockets be oriented specifically with respect to one another. It also reduces interchangeability to some extent. For example, a 17 tooth sprocket that is designed to be used next to a 16 tooth sprocket will be shaped differently from on designed to be next to a 15 tooth.
More information on Hyperglide cassettes is available in a separate article on this site.
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|---|---|
| Uniglide ® | Hyperglide ® |
| Accessories | Bicycles | Parts | Specials | Tools |
|---|
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