simple tandem conversion

[sjpt]

We are thinking of converting our fairly basic tandem to electric.

We won't be doing huge mileages, fast riding or big hills (Winchester area), but help on the smaller hills will be welcome. Combined rider weight around 155kg (24 1/2 stone).

Ideally I want a front wheel conversion, as it is simplest and allows us to keep our old strong 48 spoke back wheel. I am considering the Woosh XF07; helpful Tony at Woosh has said that will be OK, but that a more powerful option (eg their SWX02) would be better. They can only offer that as back wheel; and 26" which would involve tyre change and brake adjustment (I think they will fit, need to check in more detail).

• Does anyone have experiences with a tandem and motor similar to XF07?
• Does anybody know a good source of more powerful front conversion, still road legal 250w, preferably 700C but 26" would do?

Woosh have been very helpful and I am biased to them by various comments in different forums, but certainly not decided to buy from them. Yose is quite a strong contender too.

 

[Woosh]

I can supply a 700C front BPM kit like this one:

http://wooshbikes.co.uk/cart/#/product/uid-122-frontbpm-13ah/front-bpm-kit-with-36v-13ah-battery

 

[sjpt]

Thanks, but isn't that one 350w and hence not road legal? Otherwise it looks very attractive. Is there some option to limit the power 250w and keep it legal? I guess it would still have the strong low speed torque.

 

[Woosh]

the power is already limited, the factory 350W label was unfortunate.
It is very good at low power but the 48V SWX02 is even better and smoother.

 

[sjpt]

I guess the SWX02 is still only available 26" back?

What are the legal implications with the BPM if it is wrongly labelled? The rules are hard enough to understand without extra details like that, but it seems labelling is part of the regulations. What if we were stopped or in an accident? Thanks.

 

[DynatechFan]

in my experience 48 spoke tandem rear wheels are a hangover from a time when either (i) folks building tandems didn't know any better (ii) folks building tandems didn't know how to build strong wheels or (iii) rims and hubs were much less robust back then

Our off road tandem runs 36 spoke three cross wheels front and rear, with FR30 pinned rims - we don't run a lot of weight as my 13yo rides on the back but we maybe 120kg and we do "proper" off road. Only last week we hit a bunch of roots sticking up 2 to 3" at speed - I was fine but the shout and suspension seatpost didnt help so much on the back . . .

I was pondering a tandem conversion earlier this week and would trust the Yose kit wheel I have on my commuter to be up to the job - if there was a problem with spoke breakage I would swap the rim out for a stronger one, possibly even go to double butted spokes too - tandems always seem a bit more high maintenance anyhow, which is part of the fun (for me anyhow)

The downside would be extra weight as we use a roof carrier for the tandem, but 18kg to 20kg isnt a deal breaker

 

[Woosh]

I guess the SWX02 is still only available 26" back?

That's correct.

What are the legal implications with the BPM if it is wrongly labelled? The rules are hard enough to understand without extra details like that, but it seems labelling is part of the regulations. What if we were stopped or in an accident? Thanks.

it's the regulations. The label needs to be made by either the factory or us. If we put a new sticker on, our insurers won't cover it, so we don't chance it.

 

[Nealh]

Buy the kit and put your own sticker/label on, nice professional ones available on ebay for under £3.

 

[anotherkiwi]

That's correct.


it's the regulations. The label needs to be made by either the factory or us. If we put a new sticker on, our insurers won't cover it, so we don't chance it.

Some do https://veloks.com/ufaqs/in-the-trike-legal/

That is a 3kW motor he is "restricting" to 250W and... it has a throttle "for off road use" In Denmark

 

[sjpt]

I looked more carefully at the tandem, and the brakes will not adjust for a 26" wheel (there is more difference between 26" and 700C than I had realized).

 

[Woosh]

Stephen, go for the XF07 because it's fairly flat where you are.

 

[sjpt]

Thanks for the help everyone. I think the XF07 sounds best despite the reservations. If it doesn't seem powerful enough after a bit we can put it on my bike or my wife's, and choose a more powerful one for the tandem.

1. Is it in stock with 700C rim? I'll probably order tomorrow (busy for rest of today)
2. Can it come with brake sensors instead of brake levers, to fit integrated shift/brake levers?
3. Would it be fine with just pedal sensor, no throttle of brake sensors?
4. Are all the batteries the same physical size?
   (361 x 80 x 92 (in mm, L x W x H)?
5. It looks as if the battery will have to go on the central tube in front of the stoker. Will the cables be long enough? (image)
6. An what will be best with the pedal sensor, given the chainring on the front left bottom bracket?

 

[Woosh]

Is it in stock with 700C rim? I'll probably order tomorrow (busy for rest of today)

yes. It can be done on Monday for Tuesday, arriving Wednesday.
http://wooshbikes.co.uk/cart/#/product/uid-192-xf07kit-13ah/xf07-front-hub-kit-with-13ah-battery

Can it come with brake sensors instead of brake levers, to fit integrated shift/brake levers?

Yes. You need to add hydraulic brake sensors:
http://wooshbikes.co.uk/cart/#/product/uid-196-hdbs-red/pair-of-hydraulic-brake-sensors-for-hub-kits

Would it be fine with just pedal sensor, no throttle of brake sensors?

Yes, no throttle is OK but I would recommend you fit brake sensors fairly soon because if you keep pedaling round corners and brake, the motor may not stop.

Are all the batteries the same physical size?
(361 x 80 x 92 (in mm, L x W x H)?

Yes, same size, practically same weight. Only the cells are different. 17AH battery are made with Panasonic 18650B cells. 13AH with Samsung INR18650 cells.

It looks as if the battery will have to go on the central tube in front of the stoker. Will the cables be long enough? (image)

Yes, that's where we would recommend. We have to lengthen the cables to fit. You will need to fit one or two M5 rivnuts (supplied) to the central tube.

An what will be best with the pedal sensor, given the chainring on the front left bottom bracket?

I think split magnet disc + seat post mount pedal sensor. There is plenty of space and you can probably do that without tools.

Tony

 

[sjpt]

Thanks for your patience, Tony ... Still thinking probably XF07, but ...

• Is this dropout (see attached image) suitable?
• Is there any chance you will be getting SWX02 on 700C rims?
  You mentioned 20 July in an email, is this still likely?
• How practicable would it be to rebuild the SWX02 into a 700C rim?

Also

• Are there any practical differences between the 13AH and 17AH batteries other than range? Performance? reliability? number of recharges? etc etc
• You didn't mention the 15AH ones. Any special reason?

 

[Woosh]

Is this dropout (see attached image) suitable?

if that image is taken as of the outside of the fork then yes.

Is there any chance you will be getting SWX02 on 700C rims?

48V SWX02 in 700C will arrive in August.
36V SWX02 in 700C will arrive in September

How practicable would it be to rebuild the SWX02 into a 700C rim?

Not very. I don't have spare rims and it will take about 1.5 hours do do without the spoke machine. The spoke machine does the same job in 1 minute.

Are there any practical differences between the 13AH and 17AH batteries other than range? Performance? reliability? number of recharges? etc etc

Not much difference in performance, mainly in range. As you recharge less often a larger capacity, 17AH is still better on every aspect.

You didn't mention the 15AH ones. Any special reason?

we try to phase them out from inventory. We still have a small stock of 15AH HL batteries for support.

 

[sjpt]

OK, I think I'm ready to go with XF07. If I order online I guess I should include the hydraulic brake sensors you mentioned. You also mentioned split magnet disc + seat post mount pedal sensor and appropriate cable lengths for the tandem install; will those come with it? Anything else I should mention on the order?

 

[Woosh]

we usually check the pictures that the customers email us for the following:

1. which pedal sensor is easiest to fit. The left pedal sensor needs the left BB cup made in metal, it won't mesh with a plastic left cup. The BB axle needs to be 122mm-125mm, short spindle will not leave enough gap between the BB cup and the inside face of the crank. If the customer still wants to have the left side pedal sensor because it's better and easier in the long run, then we would supply a replacement bottom bracket if necessary. The other type of pedal sensor is to go on the right hand side (drive side). For this, we supply a split magnet disc comprising two half circles and a metal circlip to keep them together. It's easier to fit but because the magnet disc is exposed, it may get disturbed in the long run. The sensor head is mounted on an adapter, cabletied to the seat post. It's easier to fit.

2. where to put the battery. Does it need additional rivnuts?

3. where to put the LCD and the thumb throttle

4. Can the bike have sensored brake levers? if not, then we'll ask the customers to order stick on hydraulic brake sensors.

That's why kit enquiries are dealt with by emails.

 

[Woosh]

You also mentioned split magnet disc + seat post mount pedal sensor and appropriate cable lengths for the tandem install; will those come with it?

Yes.

Anything else I should mention on the order?

We'll email you if we need any pictures.

 

[sjpt]

Thank you, I have just placed the order and sent an email with various pictures. I'll be out for a bit (actually riding a bike rather than sitting at a computer looking at them). I assume we'll continue now by email.

 

[sjpt]

Ordered Tuesday, arrived today Thursday.

We have it mainly fitted and have done a first very short ride. Looks promising; it got us up a hill (with help from us) that we would not usually try. A bit noisier than I expected but perfectly acceptable.

We still have the brake sensors to fit; we knew we couldn't use the standard brake levers as the tandem has integrated brake levers/gear shifters.

Fitting was all fairly easy; a couple of problems (really uncertainties rather than problems) quickly sorted out by experimentation and emailing Tony. I guess it could have taken a couple of hours. Extra time with silly things like finding where I had put our tyre levers, and making other unrelated adjustments while we were working on it. Also a spot of bother with the tyre (Schwalbe Marathon Plus) off the old wheel blowing off the new rim despite being carefully removed/fitted. I think that must have been an unusual issue with the tyre and not to do with the new kit.

It would be good to have better instructions. For example, once I had removed the crank arm I fitted the sensor just by firmly pressing it onto the axle, but that doesn't seem to be documented anywhere.

Supplied with lots of cable ties, but by the time I am sure I have the cables as I want and have tidied them up I think I will have used even more.