Converting a tandem trike

[David Stanbridge]

130kg people + 36kg tandem trike + 8kg electrification = 174kg

Would a 250w 36v rear hub motor make a significant difference on a hill?

 

[Alan Quay]

130kg people + 36kg tandem trike + 8kg electrification = 174kg

Would a 250w 36v rear hub motor make a significant difference on a hill?

Having ridden similarly laden bikes (two wheels) I can tell you that a good motor will make a huge difference.

Not all 250w motors are born equal. The Bafang BPM/CST 250w motors are far more powerful than the SWX type.

 

[David Stanbridge]

Thanks Alan, I think general consensus is pointing me towards a Bafang motor.

 

[Deleted member 4366]

You can't fit a hub-motor and keep your hub-gears!

 

[David Stanbridge]

Yep, I'm exploring dérailleur options

 

[trex]

you could keep things simple by using just one gear. The BPM is powerful enough.

 

[David Stanbridge]

you could keep things simple by using just one gear. The BPM is powerful enough.

Yes, it might be a good idea to explore that option before going to extra trouble of gears.

 

[David Stanbridge]

I'm thinking about a cyclotricity rear hub, from ebikesdirect.

Probably not my first choice of motor, but they are very local to me and I'll be able to take my trike over there for them to have a look at, before I hand over money for a kit that may not fit.
Plus it's not far to go when/if something stops working.

 

[trex]

AFAIK, Cyclotricity do not do BPM rear hub kits.
You need a lot of torque to move 200kgs up hills.

 

[jonathan75]

I found it very hard to source BPM motors with sufficiently low rpm (and the requisite 250w markings) to have good uphill torque. Paying considerably more for a CST may be an option. However what I think looks interesting are these Puma (Mac?) motors which have 150 and 175rpm versions - better torque than even a CST. They also take 48v (as do the others, but I mention because it made a world of difference for me with hills -albeit that my 270rpm CST was naff on hills at 36v, and a 200 rpm motor might not have been).

http://www.ebike-solutions.com/en/shop/motors/motors-up-to-250w/puma-rear-wheel-motor-250w.html

 

[jonathan75]

There is also a 48v 500w BPM available at 200rpm from Chinese suppliers although it would legally require single vehicle approval.

 

[shemozzle999]

The current chain wheel has 38 teeth.

Your trikes standard chainwheel is 48 teeth so the BBS standard 46 tooth chainwheel should fit.
The BBS chainwheel also freewheels so you can retain the use of your back pedal brakes or you could fit these:

http://bikemarkt.mtb-news.de/en/article/592408-hygia-ea12-mit-hall-sensor-u-feststellhebel

As the pilot you will have total control over the motor if you program the control panel to have throttle only on the lowest level, if you want the passenger to control the motor by using PAS i.e. by turning the pedals you will still be able as the pilot to cut the power using the brakes.

 

[David Stanbridge]

I think I've decided to go for this.

http://www.oxydrive.co.uk/electric-bike-kit/oxydrive-cst-11ah.html

 

[David Stanbridge]

So.... after all the research and head scratching, I've finally got the money together to buy
OXYDrive CST HT 350W 36V 13Ah electric bike conversion kit
for my tandem trike, but they are now out of stock!

Can anybody suggest any other options?

Thanks

 

[anotherkiwi]

I missed this earlier:

130kg people + 36kg tandem trike + 8kg electrification = 174kg

Would a 250w 36v rear hub motor make a significant difference on a hill?

It will be like 4 people pedalling instead of 2...

 

[David Stanbridge]

That's good, because the boy at the front doesn't pedal very much.

The problem I have at the moment is trying to find a supplier for an equivalent to the oxydrive cst kit for a 26' wheel, for around £600

 

[David Stanbridge]

These look very good value, anybody used them?
http://www.ciclotekstore.eu/b2c/productos/1/2/13/kit-bpm-lcd5/1

 

[Nealh]

AFAIK AK is the only one on the forum who has built and used one, Cyclo tek is just a brand name the kits are supplied or use to be by MXUS a Chinese manufacturer. If you are looking at BPM/CST then Woosh sell them for £500 but are 350w.

 

[anotherkiwi]

I think the ciclotek BPM may be a Bafang, I have their Mxus 250 W (Platinum) which I used up till a couple of days ago.

Good service, in Europe but prices are not very competitive with the UK these days. Or are you having a currency moment again?

 

[David Stanbridge]

I thought the prices seemed quite competitive, and they also have stock!