Honda aerodynamic scooter conversion results in 214 mpg


February 3, 2010

Jacobs demonstrating his modified Honda Innova 125i

Jacobs demonstrating his modified Honda Innova 125i

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Adding a self-built aerodynamic outer shell to a brand new Honda Innova 125i big-wheeled, step through scooter has resulted in its already pretty impressive fuel efficiency being improved considerably. Experienced Dutch cycle designer Allert Jacobs has spent the last couple of years designing, building and tweaking his machine before hitting the road recently for the all important road test.

After designing an aerodynamic, recumbent pedal-powered three-wheeler, Jacobs started to think about the possibility of moving onto bigger and more powerful vehicles. Considering the rules and regulations involved in building a roadworthy car to be too restrictive, he set his sights on a motorbike.

Streamlining performance motorcycles is by no means new. Sport machines began getting some pretty impressive results from enclosed fairings before the Fédération Internationale de Motocyclisme put the brakes on full enclosure fairings for sport motorcycles in the 1950s due to safety concerns.

Since then, work by (amongst others) Craig Vetter has shown that not only does streamlining provide gains in the speed department but also results in some impressive fuel savings. Vetter has, in fact, just recently managed to persuade the Fédération to lift its ban for electric motorbikes, opening the floodgates for electric fairing enhancements for future performance riders.

Aerodynamics is a real drag

Forward movement is of course met with resistance to that movement, from the air and from any surface an object happens to be in contact with. Most of the resistance encountered on a motorcycle however is aerodynamic. Any motorcyclist who has tucked down close to the bike will know that reducing drag results in a speed boost without the need for increased throttle. Jacobs calculated that at 55mph, a naked motorbike is likely to suffer 90% of its resistance due to aerodynamic drag.

The ideal solution for a fuel efficient motorbike would be an electrically-powered one, but Jacobs considered limited range to be problematic so he opted for the small and light engined Honda Innova 125i, which was first made available to Europeans in 2006 and was intended to replace the popular Super Cub. The Innova is already highly regarded for efficiency, Honda UK claiming it gives: "a robust 46 miles of operation on a single liter of fuel (measured at an operating urban speed of 33mph)".

Filling its 3.7 liter fuel tank got Jacobs around 140 miles to the gallon (mpg) during the initial run in period required for a new vehicle. When he started to increase throttle activity somewhat, the scooter still offered between 107 and 122mpg. Inspired by the work of the likes of Vetter, Jacobs decided to aim for 235mpg fuel efficiency for his creation.

Trimming the fat

In the Winter of 2007 Jacobs started his project by stripping away the Innova's body work and seating. He then installed footrests above the front wheel to cater for a recumbent riding position, threw in some seating and attached a nosecone. An early evaluation showed that even these modest modifications had increased the bike's top speed and fuel efficiency but there was still much more to be done.

As a result of instability issues, he was forced enclose the front wheel within the streamlining casing instead of underneath the nosecone and modify the riding position so that his feet moved down to rest at each side of the wheel when in motion. The latter half of 2008 was spent taking the design suggestions offered by a 1:5 scale model and creating a full size template from PU foam.

2009 dawned and with it the creation of the mould for the final streamlined casing. Modifications were made to the steering and the exhaust was lowered so that it sat outside of the casing. Getting in and out of the casing was made possible by slicing it down the middle and attaching the front end to a rail which extended it forward by 18 inches. Rubber cones and trips ensured a snug fit when in cruising position and an open bottom design catered for stable ground footing when at rest. The lights were also wired up and tested.

Hit the road, Jack

With everything in place and working it was time for the all important road test. Jacobs climbed into the 319 pound vehicle (88 pounds heavier than the original scooter) and set off for a 160 mile stretch of open road. His creation managed to achieve an amazing 214mpg at around 55mph with good conditions and only a 25mph wind.

Jacobs suspects that some fine tuning will see his vehicle reach that target fuel efficiency of 235mpg but as of writing, the poor weather being what it is, he has been putting his time to good use by pimping his ride, adding reflective striping and other embellishments. As the weather improves, his work in progress may yet see his target achieved and perhaps even exceeded.

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Paul Ridden While Paul is loath to reveal his age, he will admit to cutting his IT teeth on a TRS-80 (although he won't say which version). An obsessive fascination with computer technology blossomed from hobby into career before the desire for sunnier climes saw him wave a fond farewell to his native Blighty in favor of Bordeaux, France. He's now a dedicated newshound pursuing the latest bleeding edge tech for Gizmag. All articles by Paul Ridden

Going from the Vyrus 987 C3 4V: \"world\'s most powerful production motorcycle\" posting yesterday to this small-engined erodynamic extreme fuel sipper today. Ya gotta love it! This is more to my liking. Take the same design principles and scale it up slightly to a tadpole 3-wheeler and you\'ve got a highly useful commuter/errand runner that still might get over 150 mpg if fully enclosed. If Jacobs fully enclosed the cabin on his current design, I think he might achieve his 235mpg goal and if he went further to enclose the bottom and install retractable out-riggers, he might well start closing in on 300mpg (but probably not that much in normal driving or at 55mph). Way to go Jacob! Keep refining your design and we will probably see you here on Gizmag again!

Will, the tink

I suspect that will be a real bear to handle in any kind of crosswind. As well, there\'s the classic cornering peril of fully-faired two-wheelers: a strong crosswind can actually lift the banked bike off the rear wheel as the fairing acts like an airfoil. It\'s a recipe for a highside crash.


Spirit of 76....Craig Vetter has done lots of riding on the west coast hiway with his pioneering \"Freedom Machine\". He mentions that gusty side winds around Big Sur was something he worried about but found out through road testing that it was self-correcting (if I remember the article right). His machine (especially the flat test surfaces) had lots more surface area than Jacobs here. Here is a link to the article: He didn\'t have any of the \"cornering peril\" that you mention either. I think Jacobs has done a real nice job of streamlining and should have no problems at all with side winds.

Will, the tink

I am an engineering technician and have build several fairings. I regularly contact other buliders and motorcycle racers. My experience is that side loads can affect any vehicle from my bicycle to the family van. The key factors are to curve the sides a bit, round the edges, and keep the body center of pressure behind the center of mass. The Jacobs bike is currently close to the state of the art. To high side a faired bike in a cross wind is very hard to do leaning into a turn. The weight from braking would have to be nearly all on the front wheel and the rider would have to overcorrect the steering. Even if a rider puts a faired bike down, the fairing protects the rider from road rash. See the WISIL recumbant bicycle club article. The more common problem is to keep the front wheel from getting light due to lift. This is fixed by putting some weight in the nose, adding a chin spoiler, or making the body angle of attack more negative ie. nose down. ALWAYS ATTACH THE FAIRING TO THE FRAME, NOT THE STEERING GEAR!! Even a small surface can affect steering control in a crosswind. A Kawasaki 125 Eliminator with a Rifle Yamaha fairing through Craig Vetter is a great way to start your own high miler project for about $4500 USD. A fairing really helps double the range of an electric bike also.


fully enclosing it would bring the mileage numbers way up.the racer's at Battle Mountain,Nevada in their fully enclosed streamlined bicycles[60-80 plus miles per hour,have tiny slits for the tires,compared to Jacobs large opening at the bottom.As far as wind loading,I would think,extending the wheel base and making sure their is more surface area behind the CG.Like a arrow with fins on the back,not much can upset it's flight path.I hope we some production vehicles soon,the time is right.I would love to see a streamlined 3 wheeled tilted,like the BMW Simple concept ,with a small turbo diesel,like the new Honda engine.These vehicles can pull down incredible fuel mileage.As of 2013,VW is talking about putting the XL1 VW,into production.NY to LA on 50 -70 dollars in fuel,yes,lets get these gas hogs off the highways

Thomas Lewis
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