Monday, February 7, 2011
Recumbent Highs and Lows
Recumbent Highs and Lows
by Bevin Chu
Taipei, Republic of China
February 5, 2011
I recently penned an article on recumbent bicycles, entitled "From Wedgies to Bents." In it I explained why I was abandoning traditional diamond frame bicycles, and moving to recumbents.
In this article, entitled "Recumbent Highs and Lows," I share my personal views on the relative merits of high racers, mid racers, and low racers; and explain why the SWB low racer is the recumbent of choice for me.
Recumbents are commonly classified according to two criteria.
The first is bicycle length. Recumbents are classified as either short wheelbase (SWB) or long wheelbase (LWB).
The second is bicycle height. Recumbents are classified as either high racer, mid racer, or low racer.
In theory, 2 x 3 = 6 configurations are possible. In practice, only three configurations have gained commercial appeal.
Those three are:
SWB high racers such as the Bachetta Corsa
LWB mid racers such as the Rans X-stream
SWB low racers such as the Optima Baron
SWB High Racers
Bachetta Corsa, SWB high racer 700C/700C, seat height 26.25" (67 cm)
The frame of the SWB high racer is simplicity itself. It is a perfectly straight tube. One can hardly get any simpler than that. As a result, the SWB high racer is as light as it can possibly be. The chainline is also as straight as it can possibly be. It is any wonder SWB high racers such as the Bachetta and Carbent have so may devotees?
Alas, they are not my cup of tea. Why? Because I have no desire to fall a full 67 cm before hitting the concrete pavement below.
LWB Mid Racers
Next to the SWB low racer, the LWB mid racer is my favorite bicycle configuration. The LWB mid racer positions the rider's buttocks close to the ground, but by keeping his back relatively straight, positions his head reasonably high off the ground, providing him with an excellent view of the road around him.
I would buy a Rans X-stream 26 in a flash, if only it would fit into my condo elevator. The biggest drawback of the LWB mid racer is its sheer size. LWB mid racers are 8 feet long behemoths! If one wants a LWB mid racer, one really needs to live on the ground floor or have a garage.
SWB Low Racers
Optima Baron, SWB low racer 20"/26", seat height 13.5" (34 cm)
For me, the SWB low racer is the most desirable of all bike configurations.
The biggest obstacle to sustained speed on a bicycle is air resistance. The SWB low racer configuration minimizes air resistance. That makes the SWB low racer the fastest of all bike configurations, bar none. For sheer adrenaline pumping speed, nothing else comes close. Not just downhill, but even on flats or gentle rollers. Except when climbing, the SWB low racer simply leaves other bikes in the dust.
But for me blinding speed is merely icing on the cake. Some SWB low racer owners barrel down steep mountain roads at speeds approaching 100 kph. I have no intention of doing anything so reckless.
For me, the main attraction of the SWB low racer is not maximum speed, but maximum safety, specifically during a fall.
As I noted in "From Wedgies to Bents," as long as one rides a bicycle, one will eventually fall. The question is not whether. The question is when.
And when one falls, the severity of one's injuries will be directly proportional to one's height above the ground. The cyclist who has positioned himself low to the ground before he falls, will minimize his injuries when the eventual fall occurs.
The SWB low racer may be the most practical configuration for many condominium dwellers, who must schlep their bicycles up and down building elevators.
A Fundamentally Flawed Automobile Design
Imagine that you had designed a performance sports car that contained a fundamental design flaw. What would you do? Change it and eradicate the flaw forever? Or would you persist for the next 50 or so years in making the best of the bad design?
You would have probably gone for the first option. If you had gone for the second then you would probably now be producing a car like the Porsche Carrera 4S - for indeed, that is exactly what German performance sports car manufacturer Porsche did.
Stemming from the Porsche's first sports car, and the first car Porsche produced in it's own right - the Porsche 356 - the Porsche 911 has maintained the basic "rear-engine, rear-wheel drive" layout concept that is a basic flaw in any car design, let alone a high performance sports car.
From "Porsche - A Performance and Sports Car Legend"
The engine should never have been positioned behind the rear axle in the first place. A tail heavy, rear engine, rear wheel drive automobile is like an arrow that has been launched backwards, with the fletching in front, and the arrowhead in back. The arrowhead naturally tries to get out front, and will do so at the very first opportunity.
Oversteer, the bane of tail heavy, rear engine, rear wheel drive automobiles such as the Porsche, VW Beetle, and Chevrolet Corvair
A Fundamentally Flawed Bicycle Design
By the same token, the conventional upright bicycle is a fundamentally flawed design. The conventional diamond frame bicycle positions the rider vertically, in an upright position, above the pedals, maximizing the risk of injury in the event of a fall.
Conventional Upright Layout is Vertical
Sabrina Bianchi, Second Place Finisher in 2010 RAAM, on a Diamond Frame Road Bike, possibly a Felt
By contrast, the recumbent, an inherently safer design, positions the rider horizontally, in a reclining position, behind the pedals, minimizing the risk of injury in the event of a fall.
Unconventional Recumbent Layout is Horizontal
pedals/feet --- seat/buttocks --- headrest/head
Bicycles: Mechanical Analogs of the Horse?
So how did the upright layout for bicycles come about in the first place? Why was the rider positioned vertically, above the pedal, diamond frame style, instead of horizontally, behind the pedal, recumbent style?
A good guess would be that primitive bicycles were mechanical analogs of the horse. Their designers probably had mental images of horses and riders dancing in their heads. In fact, primitive bicycles were referred to as "hobby horses." In China, bicycles are colloquially referred to as "tie ma" or "iron horses."
Pedestrian Curricle, better known as a "Hobby Horse"
It is not surprising that early bicycle designers put riders astride their creations in the same position as equestrians astride their horses.
That said, other bicycle designers were already "thinking outside the box." This early recumbent, circa 1902, was obviously the direct ancestor of today's Easy Racers and Rans LWB mid racers. Not all bicycle designers were mental prisoners, trapped within the upright bicycle paradigm.
Early Recumbent, circa 1902, designed by one H. Jarvis
Easy Racers Ti-Rush LWB mid racer, note the uncanny similarity to Jarvis' design
Time for a Fundamental Change
The rear engine, rear wheel drive Porsche, and the conventional diamond frame bicycle, are fundamentally flawed vehicle designs that ought to be replaced by fundamentally sounder, inherently safer designs.
The rear engine, rear wheel drive automobile layout should be replaced by the front engine, rear wheel drive layout; mid engine, rear wheel drive layout; or other, more fundamentally sound layout.
The conventional diamond frame bicycle layout should be replaced by the LWB mid racer layout; SWB low racer layout; or other, more fundamentally sound layout.