Sustain is a new name in the field of electric bikes, with a stable of three models. There's a full suspension mountain bike, a kind of cruiser affair, and the Edison, a full suspension folding bike that tips the scales at 22kg (2kg more than advertised) and retails for a very reasonable £399.
You'd think that corners would need to be cut at this price, but they're not obvious. The Li-Ion 10Ah battery and 200W hub motor are the same as you'll find on bikes costing twice as much, and there's pedal assist and throttle modes, and an economy setting for sparing the juice. The Edison will happily scoot along on the flat under its own steam, and gives you plenty of help on the hills as well, enough to stop you breaking into a sweat on all but the steepest inclines. The stated range of 15-20 miles was optimistic, but even without power this is a very rideable bike; gone are the days of 40kg behemoths with the rolling characteristics of an anchor. The gear range from the 6-speed derailleur is pedestrian, to say the least - I spent most of the time in top, and rarely went over about 12mph - but it's not a bike that really wants to be ridden quickly. The Promax V-brakes have more than enough power to get you from slow to stop.
The fact that the Edison folds is a big plus - it'll fit in the back of a family car without fuss, and you can lug it onto the train, but it's not the most compact, and really needs to be tied with a strap (not included) when folded. A bag would be a good accessory, or at least some kind of handle. It's not easy to pick up, either, and although 22kg isn't much for an electric bike, it's still a lot of metal to be hauling about - it was certainly too heavy for my more petite friends - and I'd like to see a much lighter version.
First to go would be the suspension. It's simply not necessary, especially the front forks: the riding position is so upright that you're not putting any weight on the handlebars. The wheels could shed some weight too - the rims look like they're designed for the jump park not the high street. With the money saved from losing the springs, I'd spec better, lighter wheels and tyres, and throw in a bag. The bike would probably be 2-3kg lighter, which would mean more powered miles and less tired arms...
As it is, the Edison represents excellent value for money, and it's definitely one of the better electric bikes I've tested, well suited to the shorter journeys that this type of machine is likely to make. Assuming you're strong enough to carry it, the fact that it folds is another good selling point. The fact that the Edison is continually sold out on the Sustain website is testament to the fact that it's a popular bike already, but I think it can be better still, and I'd love to see a pared-down rigid version with more emphasis on the folding.