Towards a better bicycle

Loosely speaking, the Switchblade design objective was to  optimise the overall configuration  of the bicycle, for improved rider comfort and performance. More formally, it’s a fundemental rethink of rider-powered vehicles to rider comfort, power development and transmission. The design scope encompasses physiological and bio-mechanical aspects of the rider, including rider position, muscle function, metabolics etc; as well as mechanical aspects of the machine itself:  drive train, weight, aerodynamics etc.  While mechanical quantities like power output and aerodynamics are measurable, as too are some aspects of human or metabolic performance (although not always easily), the often overlooked elements: rider stress, discomfort, fatigue, even pleasure do not lend themselves to easy quantification.

It might be argued that this sort of rethink is at odds with much current bike design which focusses on the details, on segmentation and incremental improvements of the standard configuration. It is pertinent to ask the question of whether a complete rethink is meaningful: is it possible that, dominating for over a hundred years, the overall layout of the bicycle is not already optimised for rider comfort and performance?

The answer to that question may seem ambitious: as the bicycle has evolved, commercial, social and technical factors have diminished rider comfort as a key design objective. For example, most technical innovation is driven by road racing and more general cycle sport. Yet little of this is geared towards  improving rider comfort. (This is perhaps analogous to private car design being overly influenced by motor racing.) Other examples might include suitability of any configuration to increasingly high-density motor  traffic  (a social factor?)  and the influence of what now seem like simple mechanical developments such as chain drive  on both the early ‘Safety’ designs and later, on recumbent development (a technical factor).

Product Lifecycling

The focus of current bicycle design on small detail changes is reasonably consistent with the accepted pattern of  a product or technology’s commercial  life-cycle;  most radical product design and market testing occurs in the early years which leads to elimination of  the less saleable options and markets then settle on a relatively limited but commercially viable range of products.  After this early phase of product and market evolution, the commercial prospects of a radical design shift are likely to be uncertain and do not make a good business case: small business can’t justify the costs of lengthy research; large business can’t justify the risks.  Perhaps it is unsurprising then, that, even though there may be benefits to rethinking the basic bicycle layout, it is not likely to be achieved within a commercial framework.

The Recumbent Configuration

Ignoring the ‘ assisted’ vehicles such as electric bikes, there are what might be seen as an increasing number of competitors to the conventional bicycle for self-propelled transport: adult  scooters being one trending example. Despite potential commercial success of such innovations, most of these are much less effective as actual transport than the conventional bicycle and many are more oriented towards ‘leisure’ rather than transport, per se.

The only current alternative that comes close to practically challenging the conventional bicycle is the recumbent, whether in two- or three-wheel form. There is much bias in discussions about the merits of recumbent bikes, perhaps because many enthusiasts feel as an oppressed minority. Significantly though, the recumbent bicycle’s history was adversely affected by the road racing body, the UCI, which banned them from racing in the nineteen-thirties, because they gave riders a clear performance advantage (bhpc.org.uk).  Although that ban still stands, the distance cycling records  are all held by recumbents, demonstrating that superior aerodynamics gives a very clear advantage over conventional bicycles, on the flat at least.

The Switchblade could be seen as a bit like a recumbent. But however it is described , an early development aim was to try to  exploit the intrinsic aerodynamic  and comfort benefits of recumbent riding  on flatter terrain.

Physics

However creative a solution that favorably positions a human on a vehicle so they can produce useful work as easily as possible, the laws of physics  strictly limit the design envelope.

Long distance cycling can be demanding; the laws of physics dictate that the rider has to produce physical work at an increasing rate (work/time =  power)  to make rapid progress. Gravity and mechanical losses waste energy, only some of which is recovered when going downhill. And at higher speeds, aerodynamics becomes much more important, increasing with the fourth power of speed.

But, while accepting  that reducing these losses can have a big impact on performance, a much less debated topic is the rider’s physical stress or discomfort (even if it can’t be objectively measured) for a given output. For high efforts, such as when racing, riders (or  ‘athletes’)  are working typically above 70% of their peak- or sprint-power output for sustained periods. At these levels, not much can be done to reduce the discomfort over time, aside from conditioning  the body through training. And, of course, performance takes precedence over comfort in racing. But for cycle touring and even for long-distance eventing, rider effort is nearly always below the lactate threshold (LT), say at between one-quarter to one-half of sprint-power. At these sort of work rates, levels of rider stress or fatigue are more affected by how the  work is done and, in turn, reduced stress implies greater ease in achieving a given output.

Headlong

This project has involved investigating numerous alternatives to the conventional riding positions, including the recumbent position. Objectively measuring rideability and levels of rider stress or satisfaction were problematic but much of our exploratory work was terminated simply on the grounds of showing no potential or through being impractical to develop further.

In terms of riding positions, we tried to explore as wide an envelope as possible, to search for a configuration that might at least compete with the conventional bicycle. We grouped all possible or practical ride positions into three – conventional (i.e. upright), recumbent (i.e. feet first) and prone (i.e. head first). The head first option may sound least promising (and perhaps dangerous) but Graham Obree’s ‘Superman’ machine lies within this definition and had considerable success (as shown here). We investigated several variations on a prone bicycle theme but, as practical machines, they all had serious drawbacks. We mention this design excursion mainly to emphasize the broad background of research which eventually converged on the Switchblade as a preferred solution.

Beyond the Recumbent

Having pursued and ultimately eliminated various differing ideas, including the prone riding position as described above, our research eventually converged on possible ways to more fully exploit the comfort and limited performance advantages of the recumbent format.  This became a long-term challenge and has taken many years of development.