Getting Shifty in the 'Hoods...Shifter Levers

Getting Shifty in the 'Hoods...Shifter Levers

Gears are marvelous things.  You can find them in many forms and uses through the last few centuries.  A simple block and tackle, with a rope or chain running through, is a geared arrangement that allows a small effort to shift a greater load.  Really, a simple lever can be considered to be the grand-daddy of all gear systems, as the basic concept remains the same - to shift a great load with a smaller applied effort.

Rotating gears began with wooden pegged wheels, still found today in (elderly) wind and water mills.  A simple clock, with its not so simple clockwork mechanism, is a mechanism of interconnecting gears the both regulate the release of energy stored in a simple, coiled spring, and also governs the movement of at least three different hands on the clock dial, all to keep time.  Perhaps the ultimate expression of mechanical gears was the Difference Engine, designed by Charles Babbage with assistance from Ada Lovelace, the mathematically talented daughter of Lord Byron.  
Although never constructed during Babbage's lifetime, this was nothing less than a complete mechanical calculator, and working examples of his engine have been constructed in recent years, and they work exactly as intended.  of course, echoes of this were found in the Enigma code machine that was used by Germany during the Second World War, and reverse-engineered by Alan Turing's team at Bletchley Park.

With the development of the internal combustion engine, gears for vehicles became a necessity as, despite a public perception of the ICE being powerful, they have always been inadequate for the job of moving a car-sized mass with direct gearing.  The engine must be working at a rate measured in thousands of rpm, stepped down through a gear system before it has a chance of getting the vehicle moving.

Bicycles are no different.  lets face it - human legs are not the strongest items out there.  We evolved to run far, and not terribly fast, either.  Marathon and endurance runners do as sport what we evolved to do.  Take a look at any single-speed bike.  Yes, the chainring is the larger of the two ends, with the drive sprockets typically smaller, so that the rear wheel ends up performing more rotations than the cranks.  But the actual gearing is expressed as how far you travel for one crank rotation.  For a 700c wheel, the circumference is typically 2100 mm (varies depending upon the tyre geometry).  So, at the steep end of a 53-tooth crank with an 11-tooth rear sprocket, the ratio works out as 53 ÷ 11 x 2.1 = 10.1 metres.  This is how far I would travel with just one revolution of the cranks.  Impressive?  No.  That works fine when on a downward grade or in a race-ending sprint.  But you cannot push that hard routinely, unless your name is Merckx.  Last time I checked, that ain't me.

Similarly, traveling uphill the gears become much easier.  Running a 39-28 combo, my travel distance has become 39 ÷ 28 x 2.1 = 2.925 metres.  Less than a third of the top end, and on some climbs in these parts still feels too steep (before you think "use a compact", the 39-28 gives an equivalent ratio of 35:25, easier than the compact's 36-25. So there.) So, with the two extremes of the gear ratios set out, there has to be a simple way of changing gears quickly, reliably and efficiently that does not involve stopping and turning the rear wheel around, as done by the first cyclists to experiment with gears.

The derailleur changers, and the internal hub gears as well, all use a simple technique for shifting gears.  A cable.  One end of which is anchored to a lever.  Turn the lever one way and increase the tension on the cable, pulling the derailleur across, or release the cable tension and let the derailleur springs return the gear unit towards the relaxed position.  The variety comes in the range of lever designs and appearances.

The seventies classic, the Raleigh Chopper, had a stick-shift lever, made to look like a car's automatic transmission.  Still, just a lever.  For decades the standard road-bike shifter were friction-levers screwed into nuts brazed onto the frame.  Some riders still use these, and friction levers can still be purchased new.  

A forgettable design innovation of the early eighties saw these levers migrated to the top of the stem, so that the rider could use his or her thumbs to shift while riding with hands on the bar tops.  These bikes typically came with lever extensions on the brake levers, so that the brakes could operated without moving hands from the bar tops.  Perhaps the only good thing to say about the stem shifters is that you could shift gears and brake without taking your hands off the bars, as required by down-tube friction shifters.

An attempt to fix this hand-shifting issue for racers resulted in bar-end shifters, so that the rider could move the levers when riding in the drops.  These shifters are still with us, having moved address to the ends of aero-bars on time-trial and triathlon bikes.  Thumb shifters are now standard issue on mountain bikes and commuters, the urban bikes also now sporting twist-grip shifters, where the entire handgrip rotates to control cable tension.

Yet, the standard was set in 1990 when Shimano introduced the Shimano Total integration (STI) units, combining brakes and gear shifters in the one mechanism.  Campagnolo followed in 1992 with their ErgoPower shifters, and SRAM in 2005 with their Double-Tap shifters.  They all have the same operating principle - the levers move across two, perpendicular axes.  Towards the bars for braking, as usual, but also across to shift gears.  The units also have a second lever, either under and in line with the main brake lever or, as with the Shimano Sora units, a thumb-operated lever on the inside of the unit, to release tension.  Although both Shimano and Campagnolo now have electronic shift-control systems, these are a tad more expensive, as you naturally have to have the matching motor-actuated derailleur.  So, I'm sticking with the traditional cable-pullers.

Although the three systems share the basic structure and operation, they are not interchangeable between brands. The critical difference is in the pull distances.

When you move a lever to change gear it actuates a ratchet, which maintains cable tension.  The distance that the cable is pulled is matched to the movement of the derailleur across the rear sprocket or front chainrings.  Each of the three manufacturers use slightly different cable pull distances which, although slight, cannot be tolerated in a precision gearing unit.  The old friction levers were universal, as you controlled cable pull by how far you pulled the lever.  With up to ten rear sprockets, and eleven with the latest Campagnolo cassette, there is little room for movement if the chain is to move through the gears without any sideways tension which, if not properly aligned, can result in gear-jumping and chain rattle.  Simply, the shifters must be from the same manufacturer as the derailleur.

In the Shimano range, the Ultegra 6700 system is interchangeable upwards and downwards with Dura-ace and 105.  I am not spending on Dura-ace, which brings into question value for money.

A review of the bike forums online sums it up.  Spend more on Ultegra, and you get carbon levers.  In terms of function and operational efficiency, 105 is comparable to Ultegra.  Just a little heavier owing to the alloy levers.  With the lowest possible prices internationally of NZ$403 (Ultegra) and NZ$259 (105), a difference of NZ$144 for carbon levers is excessive.  So, a pair of 105 (5700) 2-10 shifters is the order of the day.

The cheapest price was from Ribble, but it was so low that they were out of stock, with no date set for resupply.  Wiggle would only match the price if Ribble had it in stock (yeah, I haggle!), which they didn't.  So the deal went to Merlin Cycles.  The complete boxed pair, complete with gear and brake cables, was sold for the grand total of NZ$282.71.  Here they are...

Styling has improved somewhat over the last few years, and this set (2012 model) would be at least equivalent to the Ultegra shifters that were available in 2007, the year of my current 105 ride, so it is a definite step up in the world.  A positive shift, you could say.