Friday, April 30, 2010

Electric bike (e-bike) review

Electric bicycle available for rent from From e-bike review photo album
I've been itching to try some sort of electric motor transportation device for some time. While on holiday in Lanzarote an interesting opportunity cropped up. A local bike hire ( shop offer e-bikes on day rental. I couldn’t resist.

The original plan was a two day slog across the island, but after chatting with the proprietor about the practical limitations, we decide a more cautious one day trail was more prudent.

The first thing that struck me was the shear weight of these bikes -- over 40kg. Most of the weight is due to the hefty lead-acid battery (the same 150 year old technology found in most cars) which is attached to the main structural tube of the bike (where a motorbike fuel tank is traditionally situated). Locomotion is provided by a 250 Watt brushless electric motor which forms part of the back wheel hub. 250W may not sound like much, but if you’ve ever hit the ‘Watts’ button a threadmill you’ll realise that even a fit human will be hard pushed to maintain a 250W burn rate.

36V 250W brushless electric motor embedded in the back wheel hub. From e-bike review photo album
So what’s it like to ride? I must say e-bikes rock. You can cycle as much or as little as you want. There is an “ignition” key on the side of the bike. When off, this is a regular (overweight) mountain bike. But turn the ignition key to 'on' and you have a completely different experience. When you pedal the motor automatically kicks in to assist. It’s like someone giving you a gentle push from behind. Need more power? Just rotate the throttle control on the handle bar. The instant you touch the brakes the motor cuts power.

It’s powerful enough to get you up most hills without moving a muscle. However I found that on the steepest hills some pedaling was required to maintain a decent speed. On the flat the odd pedal every now and again maintains a decent ~20+ kph speed. Downhill no power is required -- just free wheel like a regular bike.

It’s not powerful enough to be dangerous. The maximum speed achievable with the motor is about 20kph -- no more than typical cycling speeds. Obviously there is nothing stopping you freewheeling or pedaling this bike to higher speeds, but the motor won’t assist you beyond about 20kph. From a safety point I don't see any difference to a regular bike.

Bike 'gas gauge' LEDs and throttle control'. From e-bike review photo album
On the handlebar control there is a three LED 'gas gauge' (green - full, amber - half empty, red - empty), a power button (not sure what that is for -- I was told it was disabled) and the all important throttle. The battery gauge LEDs where impossible to see in the Lanzarote sun (you needed to shade them to see which indicator was on). I would also have liked to had a finer resolution: three levels is a little vague, but lead-acid batteries are difficult to gauge, so this is likely a deliberate design decision. Also I’m not sure how accurate these gauges were: Fiona’s bike was showing empty after a few hours but continued to function (although a little sluggishly), while mine remained ‘full’ for the duration of the day and performed consistently.

One major feature that this bike lacked: regenerative breaking. This occurs when the motor reverses roles and becomes a dynamo: creating a resistance to motion while pumping charge back into the battery. The economics should be about the same as that for hybrid cars: I’m guessing an extension of 10% - 30% of range depending on terrain.

Who makes this bike?

No idea. There were manufacturer logos on the individual parts, but no one overall make/model that I could discern. The site calls it the “Harrier Sport” and is for sale there for €850.

Would I buy an e-bike?

Yes, definitely. But not this one. This is my check list for the perfect e-bike:
  • Must be no heavier than a regular bike. With modern batteries and high-torque brushless motors this is perfectly achievable.
  • Utilize regenerative breaking to recoup energy from downhill stretches or use pedal power to top up the battery.
  • More detailed “dashboard” showing state of battery, expected range and other interesting stats. A computer port allowing usage statistics to be downloaded and parameters tweaked would be nice (like the OBD port that modern cars have)
  • Cost under €1K, and have no tax/insurance obligations.


For a technophile like myself this is something to be tried. I have no doubt electric bikes are going to be huge in the near future. The technology is inexpensive (except the batteries maybe), it's efficient and ticks most “green” boxes. It provides many of the advantage of small motorbike/moped while still being legally classified as a pedal bike (no tax, insurance).

The weight and limited range of the lead-acid model I tried makes it a non-runner for me. But switch the lead-acid for Lithium Polymer / Lithium Ion packs, the latest brushless electric motor, regenerative braking and you have a winner. The e-bikes provided by provide a taste of what's to come. The staff were friendly and were open about the limitations of bike. Rental cost €15/bike for a single day. The rate drops for longer rental periods. They assured me that new Lithium battery models will be stocked soon. If I’m back here again I’ll certainly be booking a spin on the new model.

Related Links:
  • Rental shop website:
  • Specs of bike (MS Doc):
  • Photo gallery:
  • Location of bike rental shop (lat/lon): =28.85911,-13.835912 (at car ferry terminal, Playa Blanca)

(Date of review: 29 April 2010).

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