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E-bike tandems

Bob Cordran2019-05-22 11:30:30

New here, so apologies if this has already been discussed. 

I have been riding an entry level Dawes tandem for about four years with my solidly-built nearly-teenage son who is profoundly autistic and so is not able to ride a bike on his own.  Whilst he loves going out and about on the tandem, he is now getting quite tall and is less than 100% committed to putting much effort into pedalling (as an aside, this does make the apparently-compulsory comment that "he's not pedalling back there" even more irritating than it would be otherwise).  It can also make the very many steep hills of West Kent something of a challenge, despite having swapped to a cassette with a larger range, as I am essentially doing all the work for both of us.  

Conesquently, I'm considering acquiring an e-bike tandem, and would be grateful for any advice.  From my research so far, I suspect that retro-fitting some sort of motor to my existing tandem is unlikely to be a winner, and the few e-bike tandems I have seen on the net which look like they might be suitable are on the expensive side, to say the least, so it will help to have some expert guidance to avoid a costly mistake.

Since I'm relatively fit and enjoy the exercise (mostly) I would only really want assistance on steep hills, which is presumably where the less robust motors struggle, so I suspect that getting a less-expensive model will be a false economy. That said, the models I have seen do appear to be very heavy so I am unsure how realistic it would be to shun electric assistance on the flat.

Any thoughts gratefully received.



Thierry Kamette 2019-05-22 12:44:39

Retro fitting an electric device is not really an option as it would invalidate any form of warranty  of the tandem

Tim Williams2019-05-22 16:51:38

This is going to be no help whatsoever, but on a recent trip to Spain, I saw one of these:

It was a stunning bit of kit, but I suspect far beyond the budget of most of us.

Would one of the Tandem Expert shops be able to advise – or Dawes might be able to comment on suitability of “conversion kits”?

TimW 17:24:22

That one looks as though it has two batteries - double the power or just double the range? Electric tandems suffer from the disadvantage compared with solos of sharing the 250W maximum between two people rather than one.

We hired the Circe Helios electric tandem (Shimano steps E6000, for the weekend, squeezed it into the back of our Focus estate and cycled around Bristol. Great for the hills, and with the Alfine hub with electronic gearchange, it changes down to 2nd gear when you stop, which is great at traffic lights or when a car comes out in front of you and stalls when you're going up a hill! But we decided we didn't need it in relatively flat Suffolk. They do some retrofits too now.

David Ross2019-05-22 17:54:43

I'm sure JD Tandems is too polite to highlight the range of tandems they offer, however it would be our first port of call if we were in the market for one.

JD Tandems electric tandem range

Chris Bishop2019-05-22 18:12:42

JD Tandems will let you try an E Tandem with no pressure to buy one

Richard Scrase2019-05-22 19:51:19

I bought a retro-fit e-tandem on ebay, rear drive, battery in rack above, rather nice 1980's old Orbit tandem. My aim was to use it as family transport to move an adult, 11 year old and three year old in a child seat. The retro kit (@£300) moved us along reasonably well (10-12mph on flat without pedalling) but the overall weight of motor, battery, child-seat made the whole difficult to park, so I sold it on. So we're continuing with our Thorn discovery for now. I suggest test riding and then taking your time with ebay.


Steve Edmunds2019-05-23 08:53:44

Just to endorse what was said re JD Tandems, in my experience they work hard to tailor options to your needs and there is no high pressure salemanship


Bob Cordran2019-05-23 09:11:18

Thanks for all the very helpful comments.  

It does sound as though retro-fitting is not the way forward for what I need.  

Whilst the Circe looks good, I'm not keen on the small wheels - I'm a daily Brompton user which is fine for commuting but I would be wary of that wheel size for long distances on the dodgy road surfaces round my way.

The Moustache and Orbit tandems look the most suitable for what I need and I would be interested to know what difference the two motors on the Moustache makes (I assume more power when needed).  There is no getting round the price, though - but I'm sure this is a "you get what you pay for" situation.

I will definitely speak with JD Tandems - and also hope for a lottery win...


Tim Dowson2019-05-23 09:52:13

There was some discusion recently about retro-fitted systems using a motor in the front wheel, but the forks giving way under the strain. But if front tandem forks can be made to cope with a front disc brake, is it not possible to also retro-fit stronger front forks, for a front motor?  I would expect the braking force of a disc to be rather greater than the accelerating force imparted by a motor.

Dennis Andrews2019-05-23 20:40:56

We are currently in Snowdonia with our Moustache Samedi. We are finding that even in the hilliest terrain it's range is in excess of 40 miles with its two batteries. It will climb a 1 in 5 quite happily and it hasn't broken the 11 speed chain yet!  Dennis

Michael Hughes2019-05-24 19:48:40

Despite your concern about small wheels I strongly recommend you take a look on Ebay at the new bikes offered by Ecosmo a Birmingham based firm

They offer an electric folding tandem easy fit in a normal car boot and not a lot of hassle to fold and unfold.

It has 7 speed derailleur gears and a 36v 250 watt motor

It costs just under £1000 but you can return it within the first 30 days if it does not meet your needs. Normal protection for online purchases is return within 14 days

I have the non electric version which we decided to leave with our friends in Prague for them to enjoy and to have a tandem available to us to use there when we visit


Michael Hughes


Simon Ward2019-05-26 18:21:09

I fitted a powered front hub to our 10 year old basic Viking Tarantino with 17Ah battery. I'm in a similiar(ish) situation in that I don't mind the exercise although the wife's input is slowly diminishing. I bought the conversion from 'Woosh' bikes and can thoroughly recommend them. I fitted it last August & although I've only done around 800 miles since conversion it has performed well. It certainly smooths out the undulations. Comes with throttle & pedal assist although I've never really used the throttle except to check it still functions every now & then. Check out pedelecs forum for more comprehensive discussions on ebike conversions et al..

Simon Ward2019-05-26 18:37:40

As an aside the total cost was around £550 delivered to Inverness. I fitted it myself in a couple of hours & the only real problems were getting the wheel centred in the dropouts (very tight clearances & 'tubular' fork construction) & drilling the holes for the battery/controller - hard access for drill due to frame tube configuration. I have heard that a rear wheel option would have been more beneficial although I think that option was screw on freewheel only (not cassette). I'm quite happy with my purchase & in this configuration it gives 'all wheel drive'!!

Geoffrey Booker2019-05-26 19:59:21

I recently retro-fitted a Bafang mid drive kit to my tandem trike. Only had three hilly rides so far but it has been excellent so far. We are only using it on hills and long tiresome drags but it is a great help. The motor, controls and battery cost around £900.00. I had to buy a chainsett for the through drive as the old one didnt fit a square taper bottom bracket.

Sorry, Picture upside down!

2019-05-26 22:13:17

For hills, the Bafang mid drive is very effiecient as the drive goes through the rear cassette gears, just like a car, so with two riders NOT pedalling a 250W Bafang could climb a 15% climb at 4.5 mph, 9%  in 5th at 7.5 mph, or a 5% hill in 9th at 13 mph, and2 0 mph on the flat, but the Bafang software limits the assisted speed to 15 mph.

This is using a 36T chainring, and 9 speed 11 to 32 rear cassette.

 If you go to the www dot wooshbike dot CO dot UK , and click on kits and then the BBS01 CD kit for pricing, and then click on the motor charts to bring up a separate page, then read the text and scroll down to the mid drive sirrico CD motor, to see the climbing advantage, AND having the motor at max efficiency (78 rpm) at any speed using the gears.

Michael Hughes2019-05-26 23:56:40

DVLA website

Clearly states that it is the rating of the motor itself which is taken into account when classifying an electric bicycle as a bicycle or a motorcycle.

Above 250w the machine is regarded as a motorbike for which registration, driving licence, insurance and motorcycle helmets are required for use on public roads.

I t should also be noted that machines powered by motors above 250w are not allowed on cycle paths, hence can only be used on private land with the landowners permission.

The provision of switches and cicuitary to downgrade the motors performance does not make any difference,it is the rating on the motor that counts.

Perhaps the Tandem Club should press for a change in this rule, at least in respect of tandems maybe asking for the limit to be raised to 500w

2019-05-27 07:39:04

I think that 250 watts is more than enough, even for a tandem.   I had an electrified tandem catch me whilst out on my solo bike, while out climbing a Derbyshire hill just recently - about 5%-10% gradient to 400m.  I'm reasonably fit and often use electric bikes as pacers/targets to try and catch

Geoffrey Booker2019-05-27 13:47:21

On a slightly different tack, the mid drive motor is best fitted to the rear bottom bracket. 

Fitting the Bafang to the front eccentric is not possible due to insufficient clearance.

The main disadvantage with fitting it to the front bottom bracket, if it is possible, is that the captain and stoker pedals will go out of phase as the captain can stop peddling independent of the stoker. That is not ideal in my mind as it upsets the balance of the tandem, and will be different everytime both parties begin to pedal again.