Gears

Gearing for distance freaks

“The [single] gear ratio was something we did not choose lightly, but once chosen, we did not change it …. Soon they will show us gearing that corresponds to every slope and to every state of mind. There will be gears for young girls, for brides, for family men, for skinny and fat people, for sluggish people and for drug addicts.” ~Henri Desgrange, L’Auto-Vélo, 1902

Double or triple your fun

If you already think cyclists are an argumentative lot, just bring up the subject of suitable sprockets … but advisedly not at the same time as lighting, or steel frames versus carbon fibre!

Ratio rants are not new, as one might discover by digging into the archives of two competing French newspapers at the turn of the 20th century—L’Auto-Vélo, edited by Tour de France promoter Henry Desgrange and Le Cyclist, published by derailleur inventor Paul de Vivie, AKA Vélocio.

Aside from fixed or single-gear penitents, most long-distance cyclists have embraced muli-geared bicycles, since Saint Vélocio brought light into the world, a hundred years ago. Though lightly-loaded “sport touring” bikes won’t usually require the ultra-low gearing of a heavily-loaded touring bike, marathon riders usually like to have a range of gears that will get them up steep grades, 500 kilometres into an “ultra.”

“It is a timid Tour [de France] that avoids the true difficulties. Why does it not go over the Galibier, the Izoard, the Tourmalet? Then one could see how good a single-speed bike is. L’Auto keeps simpletons in the belief that a single gear is sufficient to go anywhere one desires. With all the hypocrisy that surrounds the media coverage of the great race, cyclotouring novices are convinced that a Tour de France bike is the best bike under all conditions …. And then they get stuck with unsuitable bikes.” ~Vélocio, Le Cycliste, 1910

Cranks

The main debate today usually revolves around the choice between triple-chainring cranks and recently introduced “compact” doubles.

Over similar ratio spreads, the triple has the advantage of closer spacing. In practice, this means that when you bail out of the big ring, on, say, a 50-40-30, the drop is only 10 teeth, rather than the common 16T drop—from 50 to 34—on a compact double. The smaller difference—10 teeth is ideal—means you don’t lose your cadence and end up spinning like the proverbial hamster, or double-shifting to maintain existing cadence.

If a double has an advantage, it is the narrower range the chain has to travel out of line. There is not so much worry attached to “cross chaining“— avoiding small-cog-to-small-ring and, especially, large-to-large. A double will also have a narrower “Q factor”—the outside distance between crank arms. The few ounces of weight saved is irrelevant.

On my brevet bikes, I run a 30-40-50 up front and Campagnolo’s biggest spread on the rear: 13-29. My heavier Blériot sports (Shimano) 24-36-46 X 12-30.

The middle and big rings receive most use on a triple. Granny gets lonely, but is always there on a long ride, when a steep grade pops up.

Campagnolo offers a 30 tooth inside ring for its triple, while most compacts offer stock 34.

The Italian component maker has recently introduced its ultra-narrow 11-speed line. Long-term durability is yet to be proven, but “extremely advanced materials” allow Camapagnolo to claim “without a shadow of doubt that long-term endurance will not be a problem, even for those who use their bikes every day.”

Ten-speed (which some contend isn’t long-wearing enough) has been relegated to Centaur groupos and below. Crankarm lengths are 170, 172.5, 175, except for the new Super Record which offers 170, 172.5, 175, 177.5, 180 mm.

Triples are represented by the “Comp” line of components, with crank lengths of 170, 175 mm. Comp cranks still use traditional, tapered bottom brackets.

Shimano road components are headed by DuraAce (with compact and traditional doubles only), followed by Ultegra, and 105 still gets high marks as a reliable middle-of-the-road groupset. Both the Ultegra (model FC-6603) and 105 (model FC-5603) triple come with 30-39-52 and offer crankarm lengths of 165/170/172.5/175mm.

SRAM’s recently introduced Apex line of components, provides a lowest gear of 28.4 inches, based around a compact double (34-50) and an 11-32 cassette.

The widest crankset options, including crank length variations—with 11 choices, from 155-185—are offered by French manufacturer Spécialités TA, whose classic Pro 5 Vis (Cyclotouriste) crankset was the choice for generations of distance devotees.

Bottom Bracket

The bottom bracket is an integral part of the drive train around which everything else revolves and must be considered in concert with the rest of the crankset. In order to obtain the correct “chainline” with a given system, the correct length spindle is needed. A triple will need a longer spindle.

There are a myriad of cup thread sizes we need not worry about here. Most are going to be British ISO. Older bikes will have cup-and-cone BBs; newer use sealed bearings.

The introduction of “integrated” bottom brackets by the leading manufacturers (Shimano “Hollowtech,” Campagnolo “Ultra Torque”) have moved bearings outboard and made the BB spindle part of the crank arms.

Cogs

Rear cogs or “cassettes” today are carried on a “freehub” with integrated freewheeling mechanism. This makes a stronger wheel than the old threaded hub/freewheel. Modern cogs have machined ramps which assist the transit of the chain across the range. Combined with indexed shifting, changing gears has never been smoother … as long as they are kept well-adjusted.

As noted elsewhere, Campagnolo’s widest range is the 13-29 cog set. Shimano road cassettes carry up to 27 teeth (16-27 or 12-27), while their mountain bike cogs range up to 34 teeth. SRAM Apex tops out at 32 teeth.

Cassettes are widely available from 7- to 11-speed. Many cyclotourists consider 8-speed to be ideal. It allows closely-spaced, wide-range gearing and wears well, due to a wider chain.

Derailleurs

Rear

The main consideration here is whether you will need a short- medium- or long-cage mechanism. A triple, with wide range gearing, will require a long-cage derailleur, needed to take up the extra chain length. Parallelogram movement is also optimized on many derailleurs according to the maximum recommended cog size.

Front

There are many variations on the front mechanism: top- pull, bottom-pull, “quick shift” (QS), traditional clamp-on, braze-on (requiring a tab brazed on the frame or an adapter clamp), etc. Most road bikes are going to be bottom pull, so it’s just a matter of matching your chosen groupo. Of course, a triple crankset is going to demand a triple cage derailleur, up to the job of shifting through 3 rings and accommodating the wider range of chain angles.

Chains

Chain size varies with the number of gears on the cassette.

Gears	Chain sizes	Pin length
8-speed	1/2″ x 3⁄32″	7.2 mm
9-speed	1/2″ x 11⁄128″	6.6 mm
10-speed	1/2″ x 11/128″	5.9 mm
11-speed	1/2″ x 11/128″	5.5 mm

 
Both SRAM and Wipperman offer “quick links” that make chain removal simple, sans tools. There is currently no after-market chain/link for Campagnolo 11-speed.

Related: See also VeloGarage tags Gears and Drivetrain