26 inch electric motor wheel conversion for the front of a tandem

[Polar Bear]

This is the chosen route after considering both front wheel and bottom bracket motors.  Each is a compromise but the choice is front wheel.

So, anybody bought a new front wheel kit recently and would care to recount their experiences please?  Looking for a legal kit for assist only, not an illegal kit for hooning.

[Efrogwr]

I fitted a Cytronex motor to Mrs E's bike; she's very happy with it.

Ordering is straightforward; you choose between options at each stage, then place the order.

It's not cheap, but it's built to order in the UK and fits straight on to the bike. Customer service is good. I had a couple of queries that were answered promptly and helpfully.

Keyboard Warriors disparage the small battery capacity and the (legal) power output. They disregard that it's a light means of assistance, not a back door means of acquiring a motorbike.

Rosie's commute is a twenty mile round trip with three 15% hills on the way back.

[numbnuts]

I used these  people https://electric-bike-conversions.co.uk/
in 2016 so far so good

[CAMRAMan]

I've used Wooshbikes in the past. Their customer service is very good and their kits are good value. https://wooshbikes.co.uk/cart/#/category/uid-8

[Frank9755]

Cytronex certainly used to, and I believe still does, use the Tongxin as its motor. 

My main experience with front hub motors is not recent but I do still own one Tongxin motor - and used to own two more - and am a big fan of them for most applications, but a tandem is one thing I would not use one for.  They are particularly good for providing a little bit of help to a reasonably strong rider - rather than doing most of the work for a weak rider.  And they are good for lighter riders but not heavy ones.

The Tongxin motor is a thing of beauty - hardly any bigger than a dynamo, virtually silent and with virtually no resistance when not under power.  However it has one weakness which is that its split axle and roller drive do not cope well with heavy weight, and there have been multiple failures recorded, where the motor starts to slip after a while, or the axle fails entirely.  Also they are known for not being easily repairable.

For a tandem I'd go for something a bit less gorgeous than the Tongxin / Cytronex, but a bit more robust, such as a Bafang, or even a Woosh kit as above, as I'ver heard good things about them.  The only thing which would persuade me to go with Cytronex would be if they were to assure me that they believe it would be fine in a tandem - have you asked them?  I would ask that question of anyone you think of buying from.

Otherwise, a front hub motor will be fine for a tandem on anything up to about 10% climbs.  Steeper than that and it might become difficult for the pilot to be able to get enough weight forward to maintain traction, unless you are good at standing on those types of climbs (we're not) when you might be good up to 12-14%.  The extra weight of the hub motor might help the slow speed steering a little bit (which is a different point but front of mind as it is an issue on the tandem I have just come back from riding!).

[Blodwyn Pig]

I’ve read that front wheel hub motors can cause the axle slots in the fork ends to open out / stretch, with some alarming photos on line.

[Frank9755]

I’ve read that front wheel hub motors can cause the axle slots in the fork ends to open out / stretch, with some alarming photos on line.

That is true, if the motor is too powerful for your forks and you don't fit a torque arm.  But a decent kit should cover that.  Either by giving you one, or testing that their motor is not going to shred forks. 

It's really an issue with overpowered / illegal / legal-in-America-but-not-here motors rather than genteel motors like the Tongxin / Cytronex.

[S1966W]

Another recommendation for Woosh bikes for their conversion kits.

I fitted a XF07 front hub kit to a tandem in 2018 and it's still going strong on the same 17Ah battery. Granted it's only done about 3000 miles since fitting but I've had no major problems. A couple of small issues but they were easily sorted over e-mail with the excellent Woosh customer service.

Fitting was relatively easy, the hardest part was getting access to drill holes in the alloy frame to take the rivnuts for the battery holder/controller. I had to get a right angle drill chuck in the end.

[Frank9755]

Sounds good! Out of interest, how is it on steep climbs?
Was my assessment above right or over cautious?

[BrianI]

Very interesting thread. Perhaps a conversion to my old 2008 Daawes Horizon may eventually happen,  especially since I converted it to flat bars last year.

[S1966W]

Sounds good! Out of interest, how is it on steep climbs?
Was my assessment above right or over cautious?

I must admit I rarely tackle any long steep climbs, but I've not noticed any problems with front wheel slippage on the short sharp climbs I often do. Tandem usage is now almost exclusively for ferrying my younger daughter around (my older 3 kids have already flown). I am average weight, say around 74 kgs, so it's not as if the bike is particularly firmly planted. I tend to use 'assist' level 2 or 3 out of 5, so the motor is rarely, if ever, pushed to it's limit.

[Frank9755]

Thanks. That's good to hear.

On reflection I think what I said was wrong. It's harder to completely unweight the front wheel on a tandem on a steep climb than it would be for a solo. The tandem I ride steers poorly at very low speed but that is due to its steering geometry.

I now think a front hub should be fine for steep hills on a tandem, even ones where the front wheel would lose traction on a solo.

[orienteer]

I have an ARCC front wheel motor assist on my Moulton tandem conversion. Occasionally the front wheel will start to slip, for example when cornering on a loose surface. By pulling a brake lever slightly the power is instantly cut, due to the switches in the brake cables.