Brompton Sparticle

ORIGINAL STORY FROM FEBRUARY 2009. The Sparticle has been considerably revised since.

Finding a good motor kit to electrify the Brompton is a bit like the hunt for the Holy Grail. I was, no doubt, as excited as many other Brompton owners when the June 2007 A to B announced that the age-long search could be over with the arrival of the Nano. This looked a great kit, ticking many of the problematic boxes that had thus far stood in the way of designing a suitable system. It was reasonably light (in terms of folding electric bikes that is) and the kit didn’t interfere with Brompton’s world beating fold. Unfortunately,it appears the designers have simply been unable to keep pace with demand and it is now all but impossible to get hold of a Nano-Brompton. Enter the Brompton Sparticle, designed by the Cambridge-based Electric Transport Shop, and about to be launched as we went to press.The trial prototype I was loaned came ready assembled, although you won’t be able to buy complete bikes off the shelf like this you’ll need a donor Brompton to which the kit can be fitted by ETS or yourself. Could this be the bike with miraculous Grail-like powers? A viable motorized Brompton, as A to B noted in the original Nano review, combined with train and bus, holds the key to ‘almost any inhabited area of the UK being within easy reach of almost any other’ – using only bike and public transport.

What’s A Sparticle?

A quick nose round the internet suggests that the Sparticle hub motor is something called a Suzhou Bafang, probably the 500-watt model used by Wisper, rather than the more powerful version used on the early Ezee Torq. Those motors are 36-volt,whereas the Sparticle uses a 24-volt system,so too many parallels shouldn’t be drawn. However,it seems the motor has an established pedigree, which is a good start.The rest of the kit – a sturdy looking controller box and a battery which resembles a small plastic handbag – is fitted underneath the seat,clamping around the seatpost. The battery itself slides off the control box when not in use,reducing the overall weight by more than 3kg to around 16kg .As a 12-stone,reasonably sporty,40-year-old,this is fine for me to lift above my head onto train luggage racks and like – if this sounds too heavy,you could shave a couple of kilos by going for a lighter Brompton than the M3L (which the prototype was fitted to).

Folding Fudge

Whilst the first thing you’d probably ask about on most electric bikes is ‘what’s it go like?’ – details of speed, hill climbing ability and the like – the first thing many Brompton owners would surely ask is ‘how does the kit affect the fold and the weight?’. The weight query I’ve looked at – 16-19kg isn’t too bad for an electric bike. The fold appeared to be fine as I lifted the bike out the box and unfolded it.The size has increased with the addition of the seatpost-mounted controller adding some 100mm to the height.But something is certainly adrift even once the seat is raised the rear of the bike doesn’t swing back if the bike is lifted – as you would expect without the seatpost effectively locking the rear frame in place.You have to unhook the front of the bike for this to happen. I couldn’t initially figure out the source of this invisible power working against gravity.Indeed,I rather belatedly realised what should have been obvious on getting the Brompton out the box – even in its fully folded state,the bike shouldn’t theoretically hold together,though it does. With the control box effectively raising the seat pillar height this will not fully lock the rear of the bike and provide a fixed anchor for the front.So why doesn’t it just spring apart like a crackerjack out of a box? A closer inspection up on the workstand revealed what was going on.The Sparticle uses wider, bespoke forks,to accommodate the hub motor.When clipped over the rear frame they provide what appears to be a friction fit – already this strong fit has begun to rub the paint off the rear frame.Whilst this appears to work,I certainly wouldn’t want to rely on it to keep the folded bike together time and again.Indeed, strongly shake the folded bike and it does indeed disassemble itself.Several emails to the designers established that the Sparticle needs to be fitted with the long Brompton seatpost (designed for taller riders) which, I was assured,had been used on other prototypes and locked the folded bike together perfectly.This still appears somewhat of a fudge in design terms – you end up with a folded Brompton bigger than a standard model and you rule out very short riders,for whom the extended seatpost is not suitable because it starts to stick out of the bottom of the frame. The most obvious solution to this would be to adopt the Nano design of a barmounted controller that could be disconnected from a battery hidden within the Brompton’s own front-mounting pannier.Unfortunately the controller box used here appears to be an ‘off the shelf’ model designed only to fit to seatposts.Whilst the designers have taken the time to have bespoke forks made for the kit,it’s a big pity they didn’t do the same for a controller box that would mount elsewhere,so as not to compromise the classic Brompton fold.

The Ride

Like the majority of electric retro-fit systems,the Sparticle is a simple throttle-controlled twist-&-go;you can use the thumb trigger to ease the power on and off at any speed up to about 14mph, when the power all but disappears.This rather limited top speed has a very useful upside though – it appears that the motor is actually geared for a 20-inch wheel, and the effect of putting it into a 16-inch rim is to substantially increase torque – in other words quick acceleration off the mark.That’s extremely useful for nipping in and out of stop-start town traffic and up steep gradients when you’ve got tired legs. In practice this meant only gentle pedalling was required for a very nippy throttle-assisted start.The real power kicks in at about 5-10mph and I streaked away up the gentle hill outside my house with very little pedaling required to maintain 14mph.On longer rides I failed to find a gradient that would defeat the Sparticle – it would even crawl up 1:7 hills from a standing start without pedalling, though this clearly isn’t recommended. This ‘power on demand’ characteristic would probably suit your average Brompton rider well – he or she is likely to regularly buzz through town traffic, and bike/train commuters no longer need to fear that killer climb up from the station that might be an unpleasant end to a tough working day.It will also no doubt be very handy for Bromponites who load a weekly shop or a toddler onto their bike – extra weight is always most telling up hills and this is just where such torque would be useful. With these motor characteristics it felt quite natural to let the motor take most of the strain accelerating briskly up to cruising speed – somewhere above 10mph depending on conditions – then ease off the motor power and let your legs do the relatively easy work of maintaining the speed.I found the power harder to use into nagging headwinds and up gentler but relentlessly constant gradients.You find yourself easing the throttle on, deciding you are using a bit much power and then easing it off again – hardly the most efficient riding style. Still,my test area around West Yorkshire proved ideal Sparticle country – flat stretches where no motor power is required,punctuated by what are generally short but steep hills up to around 1:5. The Sparticle loved to eat these up,with only gentle pedal pressure applied along with full throttle – producing a similar physical effort to cycling on the flat. Riding without power,I found myself forgetting that a motor was actually fitted – the motor’s freewheel seems to add very little resistance over a conventional hub.If you want to extend battery life and don’t need to tackle difficult gradients (and don’t trust yourself to lay off the throttle) there is a small plastic limiter screw underneath the controller (with a rather vague feel and easily mashed up under light screwdriver pressure) that lets you restrict power output – very noticeably at its bottom limit.

A Battery Of Facts

Phylion-branded batteries are used here – a brand associated with a batch of failures on Ezee bikes in the past. Not wishing to stir up trouble between Phylion and Ezee – each seems to lay blame at the other’s door – it seems the best summary of the situation is to say that there is at least a question mark over the reliability of Phylion batteries.Without measuring the current drawn by the Sparticle it’s hard to say if they are being overloaded (allegedly the problem on the Ezee bikes). It really needs a long-term test of the batteries on this system in real world conditions to see if they are behaving as they should.Watch this space. The control box which the battery slots onto is linked to motor,throttle and handlebar ‘Displayer’ via wires that are bundled to the rear brake and gear cables. Battery charge state is shown by two sets of lights,one on the battery and the handlebar-mounted ‘Displayer’ unit. The latter proved totally useless and should be dispensed with – all six lights stay on until the last couple of miles before flunking out alarmingly quickly. The battery indicator is marginally more useful – the first of three lights goes within about 3 miles but it takes until around 25 miles to drop to one light,and once the final light goes you still have about three miles left (all ‘Displayer’ lights still on at this stage!). As the battery is mounted behind you,the battery lights are tricky to check on the move,so the mileage here is approximate.The battery finally gave out at 39 miles after being used on a variety of around-town tasks.A very decent range,thanks to energy consumption of 9.5Wh/mile – good,but not quite as good as the Nano-Brompton’s 7.7Wh.

Conclusion

Good electric bike, shame about the rather crude fold,would be my initial judgement. Given that this was a prototype it would be nice to see some of these comments taken on board for the final production version, which I haven’t experienced. There will be those Brompton owners who won’t give this kit a second glance because of the increased folded size and the need for an extended seatpost. But those currently struggling up steep hills or with large loads might be tempted if they can live with the compromises the kit entails.Unlike the Grail’s promised powers, the Sparticle won’t imbue you with spiritual purity worthy of a great warrior,let you heal the sick or confront universal evil,but it could save you a lot of huffing and puffing and a good deal of time.