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Hairnet
Half-radial Spoking
Half-step Gearing
Handlebar
Handlebar Grip
Handlebar Stem → Stem
Handlebar Tape
Hanger
Hardtail
Hardened
Hard Anodized → Anodized, anodizing
Headset
Head Tube
Helicomatic ®
Hellenic Stays
Helmet
Dan Henry Arrow
H.F.
High (Gear)
High-Flange Hubs → Flange
High-normal → Low-normal and High-normal
High Riser
High tensile, high tension, Hi-Ten
High Wheeler
Hite-Rite
Hollowtech ®
Hollowtech II ®
Hood
Hook-Edge Rim
Hooks
Housing
Housing stop
H.P.V.
Hub
Hub Brake
Huret
Hybrid
Hydraulic
Hydroplaning
Hypercracker ®
HyperDrive-C ®
Hyperglide (HG) ®

Hairnet

Obsolete type of helmet, consisting of a network of stuffed leather straps.

Half-radial Spoking

This refers to a wheel which is radially spoked on one flange, semi-tangent on the other.

For an explanation of this design, see my wheelbuilding article.

In the days of 4- and 5-speed freewheels, 8- and 10-speed bikes were commonly set up with chainwheels that were very close in size, for instance, 46/49, or 47/50. When used with typical freewheels of the era, the difference between the two front gears was about half as large as the difference between adjacent gears on the freewheel. (One reason for this was that early front derailers couldn't handle much more than a 3-tooth difference reliably!)

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 was not a big deal in an 8-speed rig, but waskind 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). These issues are largely overcome with modern handlebar-end index shifters and narrow-spaced cassettes, but half-step requires mixing and matching sprockets these days -- no manufacturer offers an appropriate ready-made cassette.

Half-step gearing is most suitable for riding in flat terrain, where shifting is rare. It allows finer gradations to get as close to the "ideal" gear for the particular wind conditions as possible, and a wide range with even spacing.

Modern multi-range 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 a double shift.

See my Article on Gear Theory.

Handlebar

"Handle bars" on early bicycles were actually bars of solid steel. Solid handlebars became obsolete before the end of the 19th century; all modern handle "bars" are actually tubular, but the name persists.

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.

Handlebar Grip

A cylindrical, slip-on covering for the end of a handlebar, generally made of rubber or plastic, and formed to fit the hand. handlebar grips are most commonly used for flat handlebars. However, longer and thicker handlebar grips made of stiff foam rubber may be installed on drop handlebars to improve comfort. Some handlebar grips include twist shifters; see Gripshift.

Handlebar Tape

Cloth, plastic, leather or cork tape that is wrapped around handlebars to provide better grip and some cushioning. Most commonly used on drop handlebars.

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.")

Also see our article about taping handlebars.

Hanger

This term has several bicycle applications:

A derailer hanger is the part of a rear dropout to which the rear derailer attaches. It is also another name for an adaptor claw.
Dropout with built-in hanger Plain dropout Plain dropout with adapter claw
A cable hanger is a bolt-on cable stop used with centerpull or cantilever brakes. The front cable hanger is secured by the headset, the rear attaches to the seatpost bolt.
A chain hanger is a small braze-on mounted on the inside of the right seat stay. When the rear wheel is not installed in the frame, the chain may be routed over this fitting to keep it from flopping around.
"Hanger" is also an old-fashioned American synonym for "bottom bracket."

Hardtail

A motorcycle term for a bike which has no rear suspension. Some cyclists find this term offensive when applied to bicycles.

Hardened

Steel can be made to have different characteristics by various heat treating processes. These involve heating steel to various temperatures, then cooling it down either rapidly or gradually. Depending on the specific heat treatment chosen, steel may be either very hard and brittle or soft and flexible.

This is a very complicated technology, with very ancient roots. For many applications, such as sprockets and bearings you want a very hard surface to the part, but the inside of the part should be treated to a lesser hardness so as to avoid excessive brittleness and breakage.

Headset

The bearing assembly that connects the front fork to the frame, and permits the fork to turn for steering and balancing.

A headset consists of four races plus associated parts:

The crown race, which is pressed on to the bottom of the steerer, just above the crown.
The lower head race is pressed into the bottom of the head tube.
The upper head race is pressed into the top of the head tube.
The adjustable race attaches to the steerer. The adjustable race is secured by either a:
- Keyed washer and lock nut, for threaded headsets or a:
- Star fangled nut and cap, or compression rings in the case of some threadless headsets.

Threaded vs Threadless

The images below show how to identify whether a headset is threaded or threadless.

Threaded Headset Note wrench flats on locknut and top threaded race.	Threadless Headset Note pinch bolts on stem. and no wrench flats.

Traditional threaded headsets fit forks with threaded steerers. The adjustable race screws on to the steerer, and a locknut screws on after the adjustable race to secure it. There is normally a keyed washer between the adjustable race and the locknut for extra security.
Threadless headsets have an adjustable race that slips over an un-threaded steerer.

If you want to replace one headset with another, you must take into account the stack height of the new headset. There are other variations, in dimensions and in how parts are sccured. .

Head Tube

The front tube of the frame, through which the steerer passes. The length of the head tube gives a quick visual indication of frame size, because it varies more, proportionally, with frame size than any of the other tubes.

Helicomatic ®

The Maillard Helicomatic hub was an early version of a cassette freehub. It came with a cute little pocket-size tool that incorporated a spline wrench for the cassette lockring, a spoke wrench, and a bottle opener. The Helicomatic was a nice idea on paper, but poorly executed. These hubs are losers.

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 breakage 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. The cones tended to wear rapidly, and replacement cones are no longer available to fit these hubs.

Hellenic Stays

A frame design in which the seat stays don't go to the seat cluster, but rather cross outside of the seat tube a few inches below the seat cluster, then go on to be attached to the top tube a few inches forward of the seat tube.

Hellenic stays were introduced by (and named for) the British frame builder Fred Helens in 1923, and have been used off-and-on since by frame builders who wish to make their frames visually distinctive. They are of no practical value, and often cause un-necessary complication in brake-cable routing, luggage-rack attachment and installation of frame pumps. The are also slightly heavier than normal frame construction.

Recent users of this design include GT, Huffy and Nash bar.

Helmet

A protective hat. The so-called "leather hairnet" was commonly worn by bicycle racers until better designs with actual impact protection superseded it. A few cyclists, notably Dr. Eugene Gaston, medical columnist for Bicycling magazine, had taken to wearing hockey or mountaineering helmets around 1970. Club riders and racers saw the need for head protection, but there was not yet a helmet optimized for best protection compatible with a cyclist's need for light weight, unobstructed vision and ventilation. Around 1973, Mountain Safety Research introduced a modified mountaineering helmet which used cloth webbing attached by eight deformable side clips to provide impact absorption. MSR later added EPS (expanded polystyrene) foam inserts between the webbing straps. The next year, Bell introduced the Bell Biker, the first helmet designed from scratch specifically for bicycling. It used EPS as its impact-absorbing material, and had tapered ventilating inlets, as do most other bicycle helmets made since. Bicycle helmets are designed to mitigate the impacts resulting from a fall to the ground from riding height. These impacts are entirely able to cause permanent brain injury or fatalities, and account for most impacts in bicycle crashes.

Dan Henry Arrow

Dan Henry was a very influential cyclist in the 1950s and 1960s. He is most famous for the "Dan Henry Arrow" an arrow painted on the roadway with a stencil. brush or spray can, as a way of giving directions for organized rides. Many recreational bike clubs use Dan Henry arrows to mark their recommended routes.

He did a lot of pioneering work on suspension designs for bicycles, and developed 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 (down to his shorts), then put all his clothes back on again while riding on the rollers. A very cool guy.

H.F.

High flange (hub)

High (Gear)

A high gear is one in which the pedals move slowly compared to the speed of the wheels. High gears are achieved by using large chainwheels and small rear sprockets.

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.

High Riser

Wheelie bike.

High tensile, high tension, Hi-Ten

A fancy-sounding name for the ordinary tubing used to build cheap bicycle frames.

High Wheeler

The second-oldest style of bicycle, the successor to the "boneshaker," and the predecessor of the modern "safety" bicycle."

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 one exception: children's tricycles, even today, are direct descendents of the high wheeler, only smaller, and with a platform with a rear wheel at either side instead of a single rear wheel..

Hite-Rite

A spring device which attaches to the seatpost and to a quick-release seatpost bolt. It allows the rider to adjust the saddle height while riding. This was a fashionable option in the early days of mountain biking, but is no longer popular.

Hollowtech ®

Shimano's name for the hollow forged cranks used with Octalink ® splined bottom brackets. These lightweight cranks are made by welding two forged aluminum channels together.

Hollowtech II ®

The two-piece crank /bottom bracket system introduced with the 2004 10-speed Shimano Dura-Ace line. These use external bearings that hang outboard from the bottom bracket shell.

Hood

The stationary body of a brake lever, the part that attaches to the handlebars. This term is normally used when describing brake levers intended for use with drop handlebars, where the hood is intended to act as an alternate hand rest.
The rubber cover that fits over the body (above) of a brake lever.

Hook-Edge Rim

A rim with a ridge on the inner edge to help retain the bead of a clincher tire, as shown in the cross section at the right. Some older rims were straight-sided, and will not hold a tire as securely as a hook-edge rim (that is, the tire cannot be inflated to as high a pressure.) Virtually all good-quality rims in current production are of the hook-edge type.

Hooks

The drops of a drop handlebar, as in "riding on the hooks."

Housing

The outer sleeve through which a brake or gear cable is pulled. The housing transmits an equal push to counter the pull on the inner cable. Traditional housing consists of a tight spiral of steel wire, usually coated with plastic. Newer versions have synthetic liners to reduce friction. This type of housing is still used for brake cables. See also Bowden cable.

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, reducing 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.

Housing stop

A fitting found at each end of a piece of cable housing. It consists of a socket to receive the housing, with a small hole at the bottom, which will let the inner cable slide through, but hold the housing end rigidly in place. This may be a braze-on, or may be part of a clamped-on part. An adjusting barrel is a type of housing stop.

H.P.V.

Human Powered Vehicle. Technically, any vehicle powered by human muscle qualifies, but in common usage, "H.P.V." tends to refer to vehicles other than conventional diamond-frame bicycles. See the I.H.P.V.A. Website.

Hub

The middle part of a wheel, to which the inside ends of the spokes attach. A hub consists of an axle, which attaches to the forkends; a shell, to which the spokes attach, and bearings to connect the axle to the shell, permitting the shell to revolve around the axle. In the case of a rear hub, the shell would also have a provision for attaching the rear sprocket(s). Some hubs incorporate a coaster, drum, disc or roller brake. Some rear hubs also incorporate internal planetary gearing.

Rear Hubs for Derailer Gearing

Threaded Freewheel		Threaded Hub	Cassette Hub		Cassette Cluster

Hub Brake

A brake that is incorporated into the hub of a wheel, as opposed to a rim brake.

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 weatherproof, so they work as well in the rain as when they are dry.

Effectiveness of hub brakes varies greatly from one type to another; see the entries about each type. A disc or drum brake is 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. But on the other hand, coaster brakes overheat very quickly on downhill runs.

Disadvantages of hub brakes include greater weight, greater stress on the spokes, and increased difficulty in removing/re-installing the wheel.

Huret

Huret was a major French manufacturer of derailers.

Its best-known model was the "Allvit", introduced around 1960. The Allvit 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 Allvit 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 Allvit 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 Huret 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 Huret "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.

Hybrid

A hybrid is a cross-breed, the result of taking features from two different sources and creating something different, with aspects of both. The term has two common uses in bicycle usage:

Hybrid bicycles, also known as "cross" or "fitness" bicycles, are a cross between a mountain bike and a touring bike. The best of them have the handlebars and control levers of a mountain bike, with the frame, gears, wheels and brakes of a touring bike. 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 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 hybrids, 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 singletrack. 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 the use of both derailer and internal gearing on the same bicycle. Hybrid gearing has traditionally been a do-it-yourself option for bicycle tinkerers such as myself, usually by adding a derailer to a Sturmey-Archer hub. I have a 63-speed bicycle using this system. Hybrid gearing is no longer limited to the do-it-yourselfer, since the Sachs/SRAM 3 x 7, 3 x 8 and and 3 x 9 hubs have become generally available. These are 3-speed planetary-geared hubs designed to accept a Shimano-type cassette.

Hybrid gearing provides close spacing with a wider range of gears than can normally be obtained with a single-derailer system. It is also particularly well suited to bicycles with smaller than usual drive wheels, because the increase top ratio of the internal gear hub eliminates the need for unusually large chainwheels to compensate for the small wheels.

Hydraulic

Operated by applying pressure to liquid in a tube. Some bicycles (and all automobiles) have hydraulic brakes, using liquid-filled tubing to connect the brake control lever to the caliper. Hydraulic brakes have less internal friction and are immune from cable stretch, but are expensive and harder to service than cable operated brakes.

Hydroplaning

When an automobile is driven fast on wet roads, especially if it has worn-out tires, a cushion of water can build up under the tires, preventing the rubber from contacting the road. This is very scary and dangerous, because it leads to a total loss of traction.

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 guideline as to when hydroplaning is a risk. The formula used in the aviation industry is:

Speed (in knots) = 9 X the square root of the tire pressure (in psi.)

Here's a table calculated from this formula:

Tire Pressure		Speed Miles per hour	Speed Kilometers per hour
P.S.I.	Bars	Speed Miles per hour	Speed Kilometers per hour
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

An ill-founded fear of hydroplaning often leads people to buy bicycle tires with inefficient tread patterns, when they would be better off with slicks.

Hypercracker ®

This was a handy tool for removing the lockring that holds the sprocket cassette to a Freehub.

It consisted of a fitting to engage the lockring, 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 lockring 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,the Hypercracker is no longer in production.

HyperDrive-C ®

Shimano's buzzword for compact drive. Specifically, this refers to cassettes which feature an 11 tooth sprocket, and the bodies designed to accommodate them.

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.

HyperDrive "C" body Non-compact body

You can use HyperDrive-C cassettes on conventional bodies by adding a 1 mm thick spacer to the body before installing the cassette. This is a standard spacer commonly used for fine-tuning chainline with conventional freewheels. It may be necessary to add a spacer to the right side of the axle in some applications.

More information on Hyperglide cassettes is available in a separate article on this site.

Hyperglide (HG) ®

A system of ramps and special-shaped teeth on Shimano rear sprockets that permits much smoother shifting than older systems. HG sprockets are designed so that, as the chain moves from one sprocket to the next, it will engage the new sprocket before it has completely derailed from the old one. This makes for smooth, silent shifting.

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 one designed to be next to a 15 tooth.

That doesn't mean that you can't customize a Hyperglide cassette, but does mean that if you do customize, you will lose the Hyperglide functionality for some of the shifts.

More information on Hyperglide cassettes is available in a separate article on this site.


Uniglide ®	Hyperglide ®

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