Combining Technologies for Motorcycle Efficiency

For more than a century we’ve been spoiled by the sheer flexibility of internal combustion engines and the abundance of cheap fossil fuels to power them. Now the entire world is faced with cutting back on that consumption while appreciating that customers aren’t going to accept either increased costs or reduced performance and the result is turmoil within the automotive industry as rival technologies and solutions vie for attention.

There’s a tendency, shared by both the industry and its customers, to try to pinpoint a single replacement for conventional powertrains. Whether that’s electric, hybrid, hydrogen power or simply more efficient petrol engines, there’s a natural desire to come to a conclusion that one solution is the way forward, beating all the others.

It’s a natural response. People tend towards binary thinking: this is good, that is bad; but the result can be a false dichotomy. The problem is compounded by how well the internal combustion engine has filled such a broad array of roles in our lifetimes. From tiny single-cylinders to vast ship engines the size of buildings, the idea of burning fossil fuel and turning reciprocating motion into rotating motion has proved immensely scalable, and inevitably the hunt is on for a single replacement technology that’s equally flexible. The reality is that we’re already entering an era of more diverse solutions, with no single ‘correct’ answer, and it’s by combining technologies to suit each application that we’re likely to reach the best compromises.

By dint of its small size the motorcycle industry isn’t in a strong position to push ahead with radically new powertrain solutions: the R&D costs are generally high and the sales volumes and profit margins are too slim to recoup them. As such we’re often left waiting for the much larger, wealthier car industry to develop and mass-produce technologies, adopting them on two wheelers only after that mass production brings per-unit prices down. During the dominance of the combustion engine, that wasn’t a problem thanks to its easy scalability, but the car powertrains of the future might not be so easy to shrink to fit.

Hybrids are now dominant in the car market, but that term alone covers a vast array of different technologies. From mild hybrids that just get a slight extra boost from an electric motor to full-on EVs with range-extender combustion engines, all fall under the hybrid banner. It’s an illustration of the broad thinking needed to create a powertrain that meets demands pulling in all directions – environmental requirements, cost limits, and customer demands – and simply referring to them all as ‘hybrids’ helps when it comes to marketing. Many car buyers probably don’t know what sort of hybrid they have, and as long as it saves on fuel costs, they probably don’t care either.

Motorcycles and motorcyclists are different, though. Bikes’ powertrains are more visible, and make up a far larger proportion of the vehicle, so adding to them has a much bigger impact on the motorcycle’s size and weight. Motorcyclists, meanwhile, are also naturally enthusiasts: they do care about how their bikes work, and will take the time to understand it.

So far, serious attempts at building mainstream electric or hybrid motorcycles (outside the field of small, short-range scooters, which have been successfully electrified in many countries) have tended to stumble at every hurdle. The technologies are bulkier and heavier than equivalent petrol powertrains, their added expense is nearly impossible to amortise in fuel savings during the first owner’s tenure, and the customers themselves are unconvinced.

But there are technologies that make a seamless transfer to two wheels. Cylinder deactivation, for example, is increasingly being adopted: it adds no size or weight to the bike, but offers a potential reduction in consumption and emissions. Stop/start technology is another that can be easily incorporated without adding mass. Meanwhile the whole industry is looking with interest at Honda’s upcoming electrically-supercharged V3 model: in its own way it’s a hybrid, thanks to that electric blower, and there’s potential for a substantial boost in both economy and performance without a vast increase in weight.

However, the biggest gains for the future of motorcycling are likely to be the ones that transfer across all bikes, regardless of powertrain. By looking at maximising how much of the energy used can be converted into forward movement we can create an overriding benefit, and there are two key routes to that goal: reducing weight, and reducing wind resistance.

On the weight side of things, the bike industry is already a leader (consider how early aluminium was adopted for bike frames, for example, and how rarely it’s used for the structure of production cars) but there are still gains to be made. Carbon fibre and other composites, for example, have already shifted from aerospace materials used only in the highest echelons of motorsport into ones that are incorporated into mass-produced cars. Bikes are going the same way, with carbon wheels, for example, becoming more common, along with self-supporting composite seat units.

And then there’s aerodynamics. Conventionally, motorcycles are weak when it comes to minimising their coefficient of drag: with a relatively small frontal area, they haven’t needed to develop as rapidly as cars in that area, and the presence of a rider means it’s never going to be easy to adopt the sort of aerodynamically-clean shape that modern cars strive for. In an era of uncertainty over future technologies and legislation over motorcycle powertrains, when manufacturers are understandably hesitant about making big investments in either combustion engines or electric tech, aero is a field where they should be able to make gains in both performance and efficiency that can be carried across to future models regardless which direction trends take.