Cytronex E-Bike: The Lightest Electric Bicycle
A truly new technology feels like magic. (Anybody who uses an iPhone will know this effect). So picture this: you're cycling along in a lightweight single-speed bike. You're enjoying the way a one-speeder transfers your legs' power to the tarmac with minimal efficiency losses (a transmission, in contrast, costs you around 10% in efficiency).
But then you see a steep hill. Normally, you'd be forced to stand on the pedals, or to dismount. But on the Cytronex I was taking through hilly Winchester in countryside England, what I did was press a button on the right-hand side of the handlebar. And lo, what felt like the hand of God gave me a push, and I just went up that hill. Like magic, indeed!
The Cytronex concept is simple. Take a quality, low-weight bike, for example as made by Cannondale. (There is no substitute, as Cytronex' Mark Searles says, for lightness). Add an electric hub motor to the front wheel. The clincher is a battery that looks like a standard bicyclist's water-bottle, and is easy to insert or remove. The result: a normal, efficient bike you'll pedal without electric support on level ground and up light gradients, and that doesn't weigh you down with unnecessary ballast (the Cytronex package weighs 5 KGs). But when you hit a hill, or encounter a headwind, you can retrieve the motor's 180 Watts of electric assistence.
Other e-bikes are more complicated and heavier; in fact, Cytronex claims to make the lightest electrics in the world. Electric bikes can be of two kinds. Firstly, there are the quasi-mopeds, complete with twist-grip throttles. Millions of Chinese people use these, and they have their obvious purposes, but you won't find yourself pedaling much on these heavy machines, even if you can. Then, there are the so-called pedalecs that employ a sensor which knows how hard you are pedalling: push harder, and the electric motor provides more assistance. Pedalecs can be OK-looking, but at least in Europe, they are in danger of being stigmatised as senior-citizen transport.
No such danger in the case of Cytronex. The hub motor is inconspicuous, and the battery is ingeniously stealthy. You wouldn't look like you own one just because you're too lazy to pedal a normal bike or too poor to own a car. Cytronex' main raison d'etre is to increase your driving radius. As Searles says, "I wanted to enable more people to commute by bike".
Cytronex offers a range of bikes equipped with its electric system. In addition to the single-speed Genesis Day One,
I test-drove a gearshift-equipped Cannondale as well, and it worked beautifully, albeit without the simplicity of the single-speed one. For seriously hilly terrain though, a shifter is surely better.
Searles is also working on a package which will enable any well-trained bike mechanic to install electric components to a range of bikes -- even onto pre-owned ones. Initially planned for late 2009, this seems to be a bit more complicated than expected: some bikes are not well-suited to electrification. Expect Cytronex kits to reach the market in 2010.
In late November, I visited Cytronex in Winchester for some test rides and for a quick Q&A session with company owner Mark Searles.
Q: Tell me about the batteries you use, please. You mentioned they have an even better power-to-weight ratio than Li-Ion.
A: The battery cells themselves are supplied to us by a large manufacturer and we are the only electric bike system to use them. Obviously the lithium chemistries have great potential, but they are not quite there yet. Some have very good discharge characteristics but poor energy density, others have poor discharge rates but high energy density. We use a speciality NiMh cell which has an excellent combination of the two. It doesn't mean we aren't looking at lithium of course but we believe in following proper cycling principles of low weight and high efficiency so the battery has to pack a big punch in a small size.
Q: I noticed there is no regenerative braking.
A: When I first researched the electric bicycle industry I thought regenerative brakes were a great marketing idea. Sadly, unless the customer lives in the mountains, it is just marketing. Firstly, bicycles regenerate energy naturally by freewheeling - you cycle up a hill, then the bicycle freewheels down the other side reclaiming the energy. Secondly, bikes that regenerate have the motor intrinsically linked to the wheel instead of using a freewheel like our system. This has two problems: firstly they don't have gears and are therefore big and heavy and secondly on an average journey you lose far more energy turning the motor when you aren’t using power than you gain in the few percent of a journey spent braking.
Q: How much weight does the Cytronex system add to a bike?
A: Five Kilos, but you can remove the battery and switch the front wheel to the standard wheel (without a motor) in about one minute. The bike then weighs a few hundred grammes more than the original bike. The battery weighs 2.1KG and the hub motor 2.5 KG.
Q: What about cost?
A: The system adds around nine hundred Pounds to the price of a bike. An exchange or supplementary battery costs 195 Pounds.
Q: The battery is good for three hundred charging cycles and you mentioned that a customer should get used to the idea that it is a consumer durable, not a long-term investment. Is that difficult for your customers to accept?
A: Not at all, our bikes pay for themselves often within a year where customers use them instead of the car to work, so £195 replacement battery cost is not considered unreasonable. However we do recognise that it is part of the running cost of your bike so we keep the price as low as possible.
Q: Will you be exporting your bikes?
A: At the moment, our strategy will be to export conversion kits, and to train people to install and maintain them. The idea being that the customer can choose the bike they want in their local bicycle shop and then have Cytronex fitted by the shop. Right now, demand is a lot higher than our supply -- I myself test-ride every model we have, which is rather time-consuming. Our focus is on developing our technology, but at some point we may well expand our manufacturing capacities. In any case, we'll be sticking to a "made in the EU label": outsourcing to China is not an option.
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