ELECTRIC BIKE KITS

you along at speed. The ideal companion then, was that rare thing, a folding mountain bike. In this case I used the Montague Paratrooper (as reviewed in Velo Vision 25). The kit came ready-fitted and featured the very practical ‘rucksack battery’ option (rack mount also available). It attached and detaches using Electric Mountain Bike’s very own ‘emergency bail out’ connector, which can snap free without damage. It would probably have been the simplest kit to install anyway – fit the motor wheel into the forks, mount the on/off/Eco switch onto the bars along with the twist grip throttle, attach the controller under the rear of the seat then connect up and cable-tie your cable runs. Playing around with the bike on the grassy 1-in-3 banking of the local park I remembered my youth spent messing about on trials bikes – this bike really does have a similar feeling of being able to climb mean and rough gradients from a standing start. The skill is in the rider’s front to rear bal

HEINZMANN The Heinzmann undoubtedly vies with the Sunstar for the highest quality kit out there. An initial inspection of the parts confirms it – from the ‘twist and click’ style battery plug to the high quality cabling, it reinforces the idea that German-made equals quality and durability. Although the Heinzmann has been around for many years it has only recently seen the introduction of a digital controller – an excellent addition allowing for the provision of an accurate handlebar-mounted battery meter, an effective battery-saving ‘Eco’ mode and more powerful standing starts. I specified the high torque version of Heinzmann’s 200 W rear hub motor complete with eight speed freewheel and the larger capacity battery option as I wanted to test out the most varied potential uses of retrofit kits. Torque means immediate power – ideal for the steepest, roughest climbs – rather than an ability to push

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VELOVISION ISSUE 32 DECEMBER 2008

For off-roading it makes sense to carry the heavy battery in a rucksack. This means a break-away connector (ABOVE RIGHT) is needed. The Heinzmann digital controller fits neatly under the saddle (RIGHT). ELECTRIC BIKE KITS

ance and careful power application to avoid skidding the rear wheel or stalling. I also discovered why I gave up trials riding – I was never very good and kept falling off. Whilst reliving your youth in this way is great fun it saps the battery alarmingly quickly and I decided a more meaningful test would be to take it for a longer, smoother off-road run and to use the Eco power option a little more to try and gauge its potential range. This combination of bike and motor is undoubtedly great fun to ride – my initial test ride proved that much. The longer ‘Eco-mode’ run, mixing road, trail and bridleway, showed that 25 or more miles is well within its range – probably much more if fitted with slicks and used on tarmac. And, if you come to a very steep hill you can knock off Eco mode simply by pressing a button on the handlebar control and away you go.

Who would use it? I twinned Heinzmann’s high torque motor with a proven mountain bike as Steve Punchard, owner of Electric Mountain Bikes, has used this combination time and again on the rough tracks and vertiginous gradients around his home in the North York Moors. As a mountain bike guide in Dalby Forest he clearly practices for fun what he preaches as business. This makes it the one system I’ve come across which has been used repeatedly in the most testing biking conditions – good news not just for mountain bikers but for anyone considering purchasing a Heinzmann system. In the light of this kind of quality the relatively high price looks much more reasonable. Off-roading is, of course, only one use of the Heinzmann system – the lower torque version with correspondingly longer battery life would suit all sorts of applications. A quick search of the web reveals them fitted to everything from load carriers to Moultons! Surely one of the most versatile systems around.

Specifications Motor weight: 3.5 kg Battery capacity & weight: 187Wh = 1.9 kg; 345Wh = 3.4 kg Charger weight/recharge time: 475g. 187Wh version: 4 hours; 345Wh: 7.5 hours Replacement battery cost: £335 (187Wh); £525 (345Wh) Total retro-fitted bike weight: 23.6 kg Bike requirements: Front wheel version: min 100 mm dropouts. Rear wheel version: min 135 mm dropouts. Spoking: 36H. Guarantee: Battery 1 year, other parts 2 years RRP: 187 Wh kit = £1061; 345 Wh kit = £1251 – front or rear wheel drive. Seatpost mounted rucksack version kits = £999/£1189 respectively. Montague Paratrooper mountain bike, complete with motor kit = £1699/£1839 respectively.

SUNSTAR I’ve been using this kit on my Pashley PDQ recumbent for over six months now. Uniquely amongst retro-fit kits the Sunstar is a crank drive system and is a lovely piece of engineering too. It was ordered direct from French retailers, Zone Cyclable, after a brief trial ride outside their premises in Lyon. The motor itself is frame-clamped near the bottom bracket and drives through a small sprocket via a chain onto a granny-style chainring which sits inside the main chainring.

This reveals the main limitation of the system: as the Sunstar comes with its own bespoke bottom bracket and chainring you are limited to a single front ring, whereas a front derailleur system would normally give a choice of three. This was no loss on the PDQ, where gears are provided entirely at the rear end via a SRAM DualDrive setup. Other possible quibbles are lack of raw power and a very short motor-to-battery cable run, which really does limit where you can put the battery. It is clearly designed to be frame-clamped near the motor, ‘amidships’ on a conventional upright frame. The fitting process is quite lengthy overall. It involves removing your current bottom bracket and careful refitting of the Sunstar bespoke bottom bracket with integral pedal force sensor. This connects to the motor unit via a bracket which allows the motor to slide in order to tension the drive chain. The 180 W motor was never designed to give an immediate surge of power to inefficient

ISSUE 32 DECEMBER 2008 VELOVISION

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