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."

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.

Most cyclists have never experienced the comfort of a well broken-in leather saddle, because most modern bicycles come with plastic saddles which require no break in or other maintenance. Plastic saddles are also lighter and cheaper than leather ones. There is a general, major article on saddles on this site, covering: Adjustment, Angle, Front/Back, Gel, Hard or Soft?, Height, Impotency, Leather, Pads, Plastic, Posting, Prostate, Recumbents, Springs, Seatposts, Suspension, Wide or Narrow?

The two breakthroughs that allowed the safety bicycle to obsolete the high wheeler were Dunlop's pneumatic tire and the chain drive.

Some people believe that the term derives from the verb "sag", others maintain that it is an acronym for "Support And Gear."

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.

Schrader valve	Presta valve	Woods valve

The external threaded part of a Schrader valve is 7.7 mm (.302") x 32 T.P.I.

This term probably originated as a comical mispronounciation of "swag."

If the threads do not extend full length, technically it is a "bolt" but only pedants insist on this distinction.

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 ths, 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.

Older seat posts, 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 seat posts 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 use sizes between 25.4 (1") and 27.2 (1.07"). They 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 seat-post size is often an indicator of a lighter, fancier frame.

I have a Database of Seat Post Sizes for various bicycles available on this site.

More information on seatposts is available in my article on Saddles.

This 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, which wouldn't permit a standard sized square tapered bottom bracket spindle to fit throgh 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. The did continue to supply spare parts for many years thereafter, but these are no longer available.

See the 1982 Shimano Catalogue on this site.

Self-energizing brakes are quite controversial, because they can have a non-linear response, which may lead to wheel lock-up.

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 talk of a "Selle saddle", which actually makes no sense.

Rings with set screws 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.

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 requres 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 by the fact that the stresses from the shaft drive are not well resisted by the triangulated structure of a bicycle frame, because the stresses are perpendicular to the triangle.

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 singles-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.

This product was made of black plastic, with a peel & stick backing and a zip tieto hold it to the chainstay.

Since 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.

They achieved this position because they have the most successful research and development program in the industry. They 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.

• Cassette freehubs
  Shimano was not the first with a cassette hub, but they did pioneer the placement of the right-side axle bearing outboard of the freewheel mechanism, which virtually eliminated the problem of bent axles, and made possible reliable hubs with 8- and 9-sprocket clusters.

• Hyperglide and Interactive Glide clusters
  These developments did more to improve rear shifting than any change in derailer design.

• Superglide chainwheels
  A similar system for front shifting.

• Biopace chainheels
  A special shape for chainwheels which reduces knee stress and offers other benefits to some cyclists.

• SLR brakes
  Which have reduced frictional losses and a lighter action than previous designs.

• SPD pedals

• STI shifting

Shimano Date Codes:

All bicycles are subject to shimmy under the right (wrong) cirucmstances, but it is more pronounced in some than in others.

The rider feels shimmy mainly through the handlebars, so it is often assumed that the cause relates to the front wheel or the headset. This is most often an illusion.

When shimmy is related to faulty equipment, it is more often the rear wheel that is at fault, especially if the spokes are too loose.

Serious shimmy is also freequently caused by floppy, poorly supported luggage on top of a rear luggage rack.

Jobst Brandt has his own take on Shimmy, read it here.

• 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 side-pull designs also, but this term is not normally used for them, since they are a type of cantilever, not caliper brake.

Simplex also made a "retrofriction " down-tube shift lever that is considered by many to be the finest pre-index shift lever ever.

See also my page on French bicycles.

• 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.

See my Article on Singlespeed Mountain Bikes

(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!)

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.

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.

A rod used to help maintain alignment in a stack of elastomer bumpers in an elastomer suspension fork.

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.
• The denominator of the resulting fraction is the number of skid patches you will have on your rear tire.

44/16 simplifies to 11/4, so there would be 4 skid patches.

45/15 simplifies to 3/1 so there would only be 1 skid patch.

42/15 simplifies to 14/5, so there would be 5 skid patches.

43/15 can't be further simplified, so there would be 15 skid patches.

If you are an ambidextrous skidder, and the calculation gives an even result, your number of skid patches will be the same.

If you are an ambidextrous skidder, and have an odd denominator, the number of possible skid patches will be doubled.

• 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.

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.

See my article on Braking and Turning for a detailed explanation of this.

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.

• Ball bearing caliper pivots.

• Low-friction cables.

• Nylon spring bumpers.

• Reduced spring tension.
  By adding a weak return spring to the brake lever, they 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. This greatly improved 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.".)