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N.D.S.
See "D.S."
Nervex ®
Noted manufacturer of lugs, no longer in business.
Newton
The official metric unit of force.

1 Newton = .2248 pounds

An unofficial metric unit of force is the kilopond or "kilogram of force." This is the force exerted by the weight of a 1 kilogram mass in normal earth gravity, and is equal to 9.81 Newtons or 2.2 pounds.

The "kilogram of force" is a disreputable unit, abhorred by pedantic purists. Nevertheless, it is commonly used in the bicycle industry, particularly when dealing with spoke tension, since the most popular tensiometer is calibrated in these units.

Nexus ®
Shimano trademark for parts relating to internal gearing and hub generators.

This site includes a Nexus Gear Hub Technical Page and an on-line version of the Nexus 8-speed Service Manual.

"Ninth" gear
Many beginner cyclists assume that there must be some standard sequence of gears on a multi-speed bike, for instance that a 10-speed bike must have a "1st gear, 2nd gear 3rd...10th."

In fact there is no such standard gear numbering system, nor should there be, because some gears put the chain at bad angles, and should not be used.

I know of 4 different "systems" for numbering the gears of a 10 speed:

1. The 5 gears using the small chainwheel are 1-5, those that use the large chainwheel, 6-10
2. The 5 gears using the small chainwheel get the odd numbers 1-3-5-7-9, large 2-4-6-8-10
3. The gears can be ranked numerically by how high each gear is. The pattern would then depend on the sizes of the sprockets involved.
4. I used to know an engineer who used a variation on the previous system: He plotted everything out on semi-logarithmic graph paper, and came to the conclusion that his 10 speed was actually a 12 speed that was missing 2nd and 11th. He numbered his gears 1,3,4,5,6,7,8,9,10,12.
As you can see, if you try to actually communicate with somebody about your bike and use a term such as "9th gear" you will probably fail to communicate.

When discussing issues related to the function of the derailers, it is better to refer to "the second largest rear sprocket" or "the middle chainwheel".

When discussing issues related to the biomechanical aspects of gearing, it is better to use terms that relate to the actual ratios, such as gain ratio, gear inches or development.

Nipple
The nut that secures the end of a spoke to the rim of a bicycle wheel. Nipples have a normal right-hand thread, but because they are normally seen from the "bolt" side, it is often confusing which way to turn them. It is as if you were watching the hands of a clock move clockwise, but the clock was transparent, and you were looking from behind it.

Of all the things bicycle mechanics do, adjusting spoke nipples is the one that requires the most skill and experience. If you wish to learn more about this process, see my article on Wheelbuilding.

Nitto ®
Leading Japanese manufacturer of handlebars and stems, most notably the Technomic stem.
N.J.S.
N.J.S. (Nihon Jitensha Shinkokai-the Japanese Bicycling Association) is the governing body of Keirin racing.

It has very strict standards, with the intention of preventing mechanical failure and "leveling the playing field" among the athletes.

Not all of the N.J.S. standards actually relate to quality as such, but rather act to promote interchangeability of parts and tools.

N.J.S. threading and sizing standards are generally the same as for Campagnolo track parts.

Noodle
A curved piece of tubing commonly used to lead the brake cable around a right-angle bend where it attaches to a direct-pull cantilever brake, such as a Shimano V-brake ®. Most direct-pull brakes come with alternate noodles to accommodate left-front or right-front setup.*******
Non Turn Washer
See: Anti-rotation Washer
Normal
This is a slippery, dangerous term, because what's normal to one person at one time is abnormal to another person, another time. The use of "normal" to describe brake reach is a very common source of confusion and trouble.
The style of handlebar used on most English 3-speed bicycles. This is a fairly narrow bar with a slight rise, grips nearly parallel to the frame.

This design was formerly associated with the North Road Cycle Club, north of London. It is a reversible design, most often used in the upright position, but quite serviceable in the dropped position as well, for a more aggressive riding position. In the reversed position, it resembles a Moustache handlebar, but with sharper bends and a bit more drop.

The North Road handlebar is most commonly seen on English three-speed bicycles -- and usually in combination with a very short stem extension. The result is "tiller" steering -- that is, the grips are even with the steering axis or behind it. With tiller steering, controlling the bicycle with one hand off the handlebar is difficult. The cyclist's weight, and deceleration due to light braking or road bumps, make the cyclist's hand push the end of the handlebar forward. It is necessary to tense the muscles of the back to prevent turning the handlebars and losing control -- and with the entire weight of the cyclists' upper body in play, this is awkward. With a hand position farther ahead of the steering axis, the cyclist's weight, pushing forward and outward -- away from the steering axis -- tends to stabilize the bicycle. A handlebar stem with a longer extension can help solve this problem, and so can placing North Road handlebars in the drop position. If the handlebars are then too low, the stem needs to be taller as well; if too far away, a frame with shorter top tube is in order. [This paragraph added by John Allen, April 20, 2010.]

N.O.S.
"New, Old Stock". Refers to classic parts and accessories that have never been sold or put into use.

Nuovo
Italian for "new" as in the Campagnolo model names "Nuovo Record" ("New Record" --once the fanciest line of components) and Nuovo Tipo ("New type" -- once the cheapest line of hubs). Nuovo Tipo hubs are identifiable by their having no oil hole and clip in the middle of the barrel; instead, they have small oil holes in the dustcaps. Most Nuovo Tipo hubs have large flanges with round lightening holes. Unlike other Campagnolo hubs, Nuovo Tipo hubs have stamped bearing cups rather than the cups' having ground bearing surfaces. In many Nuovo Tipo hubs, the bearing surfaces are outright defective, unevenly stamped or with gouges that were present in the sheet metal from which they were stamped. The Nuovo Tip front hub uses the conventional 3/16" bearing balls rather than the 7/32" bearing balls of the Nuovo Record front hub. [most of this added by John Allen, April 20, 2010.
N.R.
Nuovo Record, the classic Campagnolo parts group of the '70s and early '80s. Some of the parts in this group, particularly the derailers, were different from the previous "Record" group; others were the same.
Nut
A fastener with female threads, usually hexagonal on the outside to fit a suitable wrench. The male thread equivalent is called a "bolt" or sometimes a "screw."

Nutted
A conventional, non-quick-release hub, with a solid axle. Nuts and washers are used to secure the axle to the frame or fork.
Shimano's system of splined bottom brackets.

Octalink ® cranks come in one of two different spline patterns:

• The original "V1 " type for:
• XTR (BB-M952 9-speed) 112.5 & 116 mm lengths
• Dura-Ace (BB-7700 9speed) 109.5 mm (double) & 118.5 mm (triple) lengths
• Ultegra (BB-6500 9-speed) 109.5 mm (double) & 118.5 mm (triple) lengths
• 105 (BB-5500 9-speed) 109.5 mm (double) & 118.5 mm (triple) lengths
• The later "V2" type for:
• Deore XT (ES70/71)
• Deore LX (ES70/71)
• Deore (ES50/51)

The V2 BBs work with FC M752, FC M751, FC M572, FC M571, FC M510-8 and FC M440-8 cranks.

• Tiagra 2005 (4401,4404)
• Sora 2005 (3301,3304)

O.E.M.
Original Equipment Manufacturer. This refers to parts sold by a parts manufacturer to a bicycle manufacturer for installation on new bicycles at the factory
• O.E.M. pricing is the lowest possible price structure, as the parts are sold in the largest quantities.
• O.E.M. packaging is less expensive per unit, because hundreds of parts are packed in a single crate, with little or no internal packaging material.
• O.E.M. parts are often cheaper versions of parts sold to the aftermarket, even though they may have the same model designation.
Offset
Fork rake
Oil
A viscous liquid lubricant. Oil, more or less the consistency of cooking oil, is used on pivots of levers, brakes and derailers and in some internal-gear hubs. A common oil for bicycles used to be Sturmey-Archer oil; Phil Wood Tenacious Oil supplanted it as the msot popular, at least in the U SA. but now has been replaced with a new environmentally-friendly version; too early (2010) to tell how it will work out.Thin spray lubricant is convenient but washes away or evaporates quickly; 3-in 1 "household" oil is acidic and will coat the insides of an internal-gear hub with brown gunk. Automotive automatic transmission fluid is a good lightweight oil available in quantity at a low price.

Not all oil is appropriate for every use. Don't use cooking oil or other oil not intended as a lubricant! Coaster brakes should be lubricated using high-temperature grease; some internal-gear hubs also are intended for grease lubrication. Motor oil is generally not suitable for use on bicycles because it contains detergents which otherwise cause it to wash out if not replenished continuously by an oil pump. If motor oil is used on a bicycle chain, the chain will squeak the next day! [This section added by John Allen, April 20, 2010.]

See also Grease and my article on chain lubrication, which describes many different lubricants.

O.L.D.
Over Locknut Dimension.
One-piece Crank
A one-piece crank (OPC) consists of a single steel forging which constitutes the left crank, axle, and right crank in a single piece of steel. This type of crank set is found on older U.S. made bicycles, and many current low-end bicycles. It is also commonly used on BMX and freestyle bicycles.

One piece, or "Ashtabula" cranks are heavy but very strong and reliable. They are also much easier to work on than any other type of crankset, requiring no special tools. You can completely overhaul a one-piece-crank bottom bracket with just a large adjustable wrench and a screwdriver.

There are two different threadings used on one-piece cranks. Most are 24 threads/inch, but some, notably older Schwinn and Mongoose bicycles, used 28 tpi. The bearing retainers and cups are also slightly different between the two models. Although they both use 5/16" balls, 24 tpi units use a #66 retainer with 10 balls, while the 28 tpi units use a #64 retainer, with 9 balls. This is one application where retainers are essential, it is almost impossible to assemble a one-piece crank bottom bracket with loose balls.

One-piece cranks only fit in bicycles designed for them, with large-diameter, threadless bottom brackets. It is possible to buy adapter kits to allow three-piece cranks to be used in this type of bottom bracket shell.

One-piece cranks are made in a smaller diameter than other crank designs, so that the bearing cones can be installed. As a result, they have to use a smaller diameter (1/2" x 20 tpi) pedal thread.

The left side cone of the bottom bracket has a left thread, and uses a locknut and keyed washer to secure the adjustment. The right side cone has a right thread, and secures the chainwheel to the crank.

O.T.B.
This abbreviation has at least three bicycle-related meanings:
• Only The Best, a bicycle brand sold by Charlie Hamburger in Boston, 1940s-'50s.
• Off The Back, i.e. left behind by the peloton, out of the race.
• Over The Bars, usually resulting from a head-on collision.
Ordinary
A long-obsolete term for a high-wheel bicycle, as opposed to a "safety" bicycle, i.e., the modern style.

Back in the 1890s, this term made sense, but using it nowadays is silly and only causes confusion.

Over-Locknut-Dimension

The distance between the outermost locknuts of a conventional hub axle, or whatever equivalent parts fit against the inside surfaces of the fork ends of a frame. They must match the spacing (see chart) of the frame that the wheels are to be installed in.
Oversized
Larger in diameter than the traditional sizes. This term is commonly used for headsets and frame tubing. Oversized parts are stiffer, and can be lighter for their weight if the walls are made thin enough. If the walls become too thin, however, they become too easy to damage by denting.

Traditional forks used 1" (25.4 mm) diameter steerers. Oversized steerers are 1 1/8" (28.6 mm) or, less commonly, 1 1/4" (31.8 mm). Details on sizes are listed under headsets.

Traditional frames used 1" (25.4 mm) top tubes, 1 1/8" (28.6 mm) seat tubes and down tubes, and 1 1/4" (31.8 mm) head tubes. When BMX racing became popular, frames built to these old standards couldn't always hold up to the rigors of BMX competition. Since the wide availability of T.I.G. welding freed designers from the need to use tubes that would fit standard-size lugs, oversized tubing became the norm for BMX frames. This design and technology were later adopted by builders of mountain bikes.

In the interest of improved chainwheel/tire clearance, some mountain bikes have "oversized" bottom brackets, with a shell width of 73 mm, rather than the standard 68 mm.