Electric Bromptons Compared: Geared Front Hub Motor Kits

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Electric Bromptons Compared: Geared Front Hub Motor Kits

ARCC e²-pod System

In 2016 I visited the ARCC Innovations design and manufacturing site in Cambridge to check out their impressive production facilities and the design work on the e2-pod first generation electric assist kit.

You can read more about my visit and about my test of an e2-pod-powered Moulton here. 

Brompton with e2-pod

A Brompton specific system was not available in 2016 but it is now, so I was excited to receive a loan model that featured the 2nd generation e2-pod system, now featuring a Bluetooth wireless power level control, something not found on many e-bikes, and a technology particularly suited to the Brompton as it avoids bending and folding electrical cables.

Electric e2-pod system motor

The e2-pod uses a 250W geared front hub motor (the system is UK spec only and must be factory fitted at the firm’s Cambridge base in the UK).

This is connected to a very solid looking aluminium ‘pod’ (wiring nexus and battery mount) which ARCC CNC machine out of solid aluminium-manganese alloy billets then polished, hard anodised and weather-sealed.

Brompton with e2-pod battery removed

The battery slots onto the front of the pod and ARCC offer 144 or 216Wh Bosch power tool batteries and there is the option of buying an even larger 324Wh Bosch powertool battery though that is not directly available from ARCC, only through other outlets.

All three capacity batteries can either be slid as they are onto the pod or used inside an adapted Brompton bag.

Using powertool batteries certainly has plus points; they are relatively widely available and reasonably priced and robust.

The main downside is that they are small capacity compared to the modern standard of 500Wh batteries, a figure that is creeping up all the time too.

Still, by its nature the Brompton tends to get used for ‘short hops’ where the rider will have to carry bike and luggage when off the bike, so smaller batteries are not the disadvantage they might prove on a bigger eBike.

Man riding away on Brompton with e2-pod

The Pod is really the brains of the system, processing information from a bottom bracket torque sensor and brake lever sensors that are cable connected to it and it also houses a 3-axis accelerometer which estimates gradient steepness and in automatic mode it can then adjust power accordingly.

As well as meaning quick motor cutout on braking, the brake level sensors allow you to activate the ‘launch control’ feature by applying both brakes and pressure to the left pedal – ARCC say the pod senses this and delivers maximum power to the motor for a period of three seconds, so that ‘an effortless get-away can be achieved for safety, when moving away from traffic lights and crossings in heavy traffic.’

Brompton with e2-pod brake switch

The pod also houses a bank of three USB-C ports on the side for phone or GPS charging.

Brompton with e2-pod no battery

Finally there is a beautifully finished handlebar control that sits next to your right thumb and lets you wirelessly Bluetooth changes in power level to the pod and also to change between manual and automatic mode.

It removes from its secure magnetic cradle style holder so you can easily slip it into a pocket as a way of making the bike less attractive to thieves.

e2-pod Bluetooth remote

The ARCC system seems designed to respond to a reasonably light pedal pressure and early selection of low-ish gears for the most effective hill climbing.

However, once you get the feel for the system it zips up hills in a very impressive manner for such a bijou motor.

The motor itself provides an assistance range of 88% – 176%. In manual mode this is dictated by the power setting and by your pedal pressure and cadence but in automatic it is applied irrespective of the power the user is putting in and is judged by feedback from the accelerometer.

At less than 3% slope, performance will be the same as manual mode but on steeper slopes the assistance kicks in progressively to reach a maximum level on a 13% (7.5°) slope.

Man riding Brompton with e2-pod

In automatic mode assistance will never be less than in manual mode, but it can be greater than manual if the bike is climbing a gradient.

In effect the automatic mode gives greater hill climbing ability for less human input. I thought of manual mode being ‘workout’ mode as it got me moderately out of breath over hilly country whilst automatic mode was treated as ‘get to work without sweating mode’.

Pros

The ARCC e2-pod system provides a silky smooth ride, the motor pulling along nicely some fractions of a second after you start pedalling, and cutting off almost instantaneously on stopping.

It’s clearly made to a very high standard too. The pod itself and the handlebar control unit are beautifully engineered and manufactured and the high tech Bluetooth approach works very well.

Man holding folded Brompton with e2-pod

It’s also pretty lightweight for an electric Brompton. Complete with battery my converted M6L Brompton weighed 34.75 pounds (15.77kg).

A non-electric M6L weighs around 25.8 pounds (11.7kg) so the complete kit adds around 8.8 pounds (4kg).

The 6Ah battery I was using weighs a bit over a 2.2 pounds (1 kg).

Removing it for folding would leave you with a 32.4 pounds (14.7kg) folded bike which is still probably just within acceptable train commuting weight (think of lifting it onto those luggage racks…).

Folded Brompton with e2-pod

Unlike some other systems (including the Sparticle featured here) it can be fitted to models with titanium forks, giving the potential for an even lighter electric Brompton than my test model.

If fitted to a titanium-specced two speed model for example you would have a circa 30.9 pounds (14kg) e-bike with battery and a sub 28.7 pound (13kg) one with it removed.

Cons

The system is not quite as immediately responsive to pedal pressure as a Bosch or Shimano mid-motor, nor does it have their raw power – but of course that approach would inevitably add more weight and shaving the grams off a folding bike is doubly important.

The buttons on the handlebar control are quite small and not quite as easy to manipulate with gloves on compared to some of the larger rubberised designs.

It’s a little more noisy than average and so will draw a bit more attention to the fact it’s an electric bike, which you may or may not be bothered about.

Summary

Man riding Brompton with e2-pod

Very possibly the smoothest performing and highest quality electric Brompton motor system out there.

It goes a considerable way towards solving many of the difficult engineering challenges that electrifying such a relatively complex folding design brings.

Price £1799 not including Brompton.

Must be fitted at ARCC’s Cambridge plant. Can be fitted to your own secondhand model or ARCC can source a new Brompton.

ARCC will honour the Brompton warranty on new bikes and any remaining warranty on already purchased models.

Read the full article here.


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