Much as I’d love to have an electric Brompton, they are well outside my budget (and probably most people’s).
So this post is looking at alternatives, and particularly, at what I did with my ten year-old bike to turn it into an electric workhorse at a fraction of the cost of a new electric bike. (There are ways to convert your Brompton to electric too – some people swear by these.)
Three Power Options
I started by trying a number of off-the-peg models at a local e-bike shop. The three basic options for powering an ebike are to put a motor in the front wheel, the rear wheel, or in the bottom bracket. Most of these work on the basis that when you begin to pedal, this activates the motor, though some have a manual throttle. Each have their pros and cons.
Bottom bracket (BB): I tested some state of the art e-bikes with a BB motor. Powering the bottom bracket makes sense because you are adding torque at the same point as your feet. It means the heavy motor is nicely centred in the frame, rather than making for a heavy back or front. What I liked less was the fact that you are increasing the strain on the chain, and it’s less easy to control the chain tension when changing gears. Also, having a great Bosch motor between my feet made the bike feel more like a power tool than a bike – and I couldn’t see how you could easily do repairs yourself.
Rear wheel: A motor in the rear wheel is in theory more stable – more of your weight sits on the rear wheel, anchoring it to the ground. However, you are committing to a more complex set up – your rear hub has to serve as a set of gears, a motor and possibly a brake too. If your battery is on a rear rack – and throw in panniers as well – then all your weight is at the back. I wouldn’t like to try lifting that out of an awkward bike rack or side door.
Front wheel: I’d had concerns about how a front wheel drive would feel – would it seem unstable, being pulled along by the nose, so to speak? But the test put my mind at rest. It felt the same as the other bikes. The risk (as I found later) is if you are turning sharply on ice, and pedalling – the motor can accelerate the wheel under you, which means you lose all traction and the bike shoots off sideways. So that’s a lesson not to have the power turned up too high. But the positives of front wheel drive are that the kit was easy to fit; I didn’t have to mess with my existing BB or rear wheel gear set-up; and the weight is more evenly distributed between front (motor) and rear (battery.)
The final choice
So I came to the conclusion that the old-fashioned method of putting a motor into the front wheel would work best. I bought a kit for about £450 from a company that has since gone out of business, but bascially this is the same kit as sold by Cyclotricity here. I opted for a 36v, 13Ah battery, pedal assist and the LCD display. It has 5 power levels. The wheel, motor and rack are all included. (This kit on the above website is currently about £525). Everything feels robust and well made, and I have had few problems in the last 18 months with this kit, which has now clocked up nearly 4000 miles. The battery routinely keeps me going for up to 50 miles.
The only exception is the rack – I have broken two in 18 months – in my view it’s simply not up to the job of carrying the weight of the battery and any normally-weighted pannier you might take to work. Both times the weld snapped, which made it wobble more, until three or four welds snapped. If you use Cyclotricity (who supply identical racks) I suggest you ask for a guarantee from them that the rack will be replaced if it fails in normal use. The offending model is pictured here.
That aside, I have been hugely impressed with the conversion, and I now do 70 miles per week commuting to work without breaking into a sweat. (The main trial is coping with riders on road bikes who don’t take kindly to being overtaken!)
An incredible workhorse
While some people carry extraordinary loads on bikes, (here’s my 7 foot Christmas tree!), often stretching the point, there are some things that only an ebike can do. For example, I’ve been able to carry tools into a nearby wood, and cut up some fallen trunks, and bring them back for the woodstore. The ebike can carry this load (maybe 80kg) easily uphill, where no other vehicle is allowed to go. Equally, I’ve carried heavy bags of wet compost, and even my Brompton on the trailer – all effortlessly!
The bumps got bigger
What I hadn’t anticipated with the ebike was the impact of the greater speed on my wrists. Every bump and pothole can deal a healthy whack to my wrists, and I was getting injuries more often.
My first tactic was to install a 2″ wide Schwalbe Marathon Plus tyre, and run it at about 60psi – which helped; but it was still not enough to cope with the shocking state of Edinburgh’s roads. So I hunted for a while for a solution that stopped short of adding full front shocks – after all, this is not a mountain bike, but a humble commuter!
The final solution has worked brilliantly: RST do a single shock fork, where the coil is at the base of the steering tube. Instead of the 100mm travel of the typical mountain bike, this has a 40mm travel, with the option of preloading – plenty enough for a commuter. The result is a smooth ride, without noticeable power loss, and happy wrists even when I hit the urban mogul fields at 20mph. I bought this from German firm Rose Bikes for about £160. Make sure you get the right steering column to fit your headset! (Too big a topic to tackle here.)
It makes me wonder how the electric Brompton copes at speed – no doubt having the battery clipped on the front helps to dampen things down – and the frame suspension in a Brompton will help too. But for now, I’m happy with this. It’s big, it’s heavy, but it does the job of getting me to work fast.
It doesn’t compete with the Brompton, which weighs half as much, and is more of a joy to ride – but inevitably slower. They do different jobs – and I’m happy with that.