Cleaning Out the Drafts: Whats Efficiency Got To Do Got To Do With It?

In 1903 the Wright brothers flew for a few seconds in a heavier than air craft of their own design. They worked outside of typical aeronautics thought, reworking and recalculating established thought. The wooden propeller they developed, hand hewn from laminated wood, was 83% efficient.

Modern Propellers, the most advanced among them, are a mere 2 percent more efficient. The Wrights had no computer models, no expensive wind tunnel testing facilities. They were just bike mechanics from Ohio with some spare time on their hands.

In the early days of the century, racers looked down on 3 speed hubs and derailleurs with pulleys. It was thought that the bend in the chain and the rotation of the pulley wheel added friction (with requisite loss of efficiency) to the chain.

3 speed hubs, with their complex internal workings, were indeed less efficient than derailleurs, although they certainly had advantages including a straight chain-line, sealed against the elements, no derailleur to snap off. Fortunately this paranoia of friction had some good outcomes: the invention of the quick release (to change cogs in the back by flipping from one fixed gear to another) and time.

Time for the tourists to perfect and explore the concept of multispeed shifting without the undue influence of racing. Racers in those days prized simplicity and low friction over all other factors. They were willing to sacrifice ease of use, smooth shifting, and even low weight in this quest for the cleanest, slickest (friction-wise) and more durable gear changing equipment. This often lead to ridiculous shiftering systems like the Campagnolo Paris Roubaix, the Vittoria Margeita, and the Egg Super Champion.

In fact, there were numberous durable, low friction derailluers on the market, being used by tourists daily. These cyclotouriste derailleurs saw a range of conditions, and endured incredible distances. The Cyclo Standard was used on four and seven thousand mile tours, with only oiling and adjustments needed.

Interestingly, hub gears have regressed in efficiency over the years: pre WWII Sachs 3 speed hubs, lubricated with oil have an efficiency of around 95% averaged across the 3 speeds.

Contemporary hubs are about 3 percent less efficient. Oddly, the Rolhoff, with its precision machining, is only 88% efficient on average. (Berto, The Dancing Chain: 351-352) This is mainly because of the sheer number of planetary gears it contains.

Tourists, from say, 1900-1985, knew another established fact of efficiency that has been lost to contemporary cyclists: Bigger cogs are more efficient. The current trend towards eleven and twelve tooth rear sprockets not only prematurely wears chains down (and cassettes and chainrings by default) but also has an adverse effect on efficiency. 12 tooth cogs are 2-3 percent less effiencent than 14 tooth cogs.

This is why the old french tourists ran 14-16 tooth cogs as thier smallest cogs in the back. The current micro-drive rage has come to its logical conclusion in the world of the BMX drivetrain. Eight tooth cogs and 22 tooth sprockets are the norm on contemporary bikes, and the resulting strains on the chains is seen in the ridiculously overbuilt chains that are needed to withstand the added stress.

Authors Bio: Patricia from Bornand raised in the Saginaw Bay Region of Michigan, I have always been the generally curious sort (sometimes too curious – sorry Mom and Dad!). When applying for jobs in high school, I begged my parents not to make me turn in any more applications until I’d heard back from the public library about a page position. Fortunately they called me back, and it set me upon the path toward librarianship…

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