Conversion for Christiania-style trike?

[dwjp]

I have a Christiania-style trike that I'd like to put an electric assist on. It's good fun to ride in itself, but hills are brutal (it weighs ~40 kg), and going further than about 5km is tough work. The front wheels have drum brakes, and there is a 7 speed nexus hub on the back with coaster brakes.

There looks to be room to put a 3 chainwheel cyclone kit on, and that looks like perhaps the cheapest option. But having read through the forum, I can't work out whether the coaster brakes would still work in this arrangement? (i.e. would the crank freewheel prevent you from back-peddling?)

Here are some other options:-

1) A geared ezee hub motor. This would require me to ditch the nexus hub (quite a waste), and install a derailleur and 8 speed freewheel. Or, I could install a Schlumpf mountain drive, which might be sufficient in itself when combined with a motor (although quite pricey). I'd also have to install rear brakes (disk or caliper), which might be tricky given the frame doesn't seem setup for them.

2) As above, but using a non-geared motor, which can use regenerative braking. Combined with the twin drum brakes up the front, hopefully this will provide enough stopping power?

3) Replace the front wheels with dual hub motors, and install new disc brakes to replace the drum brakes. Calipers are also a possibility, but they tend to be more difficult to match between sides. And again, they will be fiddly to install. Is it possible to keep the RPM of the two hub motors sufficiently synchronised so that it won't make violent unexpected turns?

I'd be very grateful for any other ideas!

I should emphasise that I'm not after tremendous speed here, a top speed of 15-20km/h will be plenty for trips to the market and hardware store.

 

[StudEbiker]

I googled the trike. It looks like there are a few different models. I think a Cyclone could be good, but you are correct about losing the coaster brake. At least I think so, someone else may correct me. I see that some of those Christiania trikes have dual discs in the front. Anyway to retro-fit yours with that set up? If you can, then I would probably be looking at a rear hub motor. Does the trike have a derailleur hanger on it or is that going to be an issue as well? It looks to me like it is not going to be easy to do what you want to do. I may be wrong, but I don't think that there would be any major problems with running one front hub motor. The motor is going to pull in the direction it is pointing in, so as long as you are steering, I don't think it will be a problem. Most rear wheel cars only drive through one wheel at a time, I don't see why you couldn't have only one motor up front.

 

[dwjp]

The front frame is steel, so whilst it might take some machining to make a mount, I think it's possible to install disc brakes there. And I'm certainly more comfortable with welding/drilling holes in steel than in the alloy of the rear frame. There is no derailleur hanger, but an adaptor claw ought to work. Thanks for the advice -- the cyclone sounds like it will be much work, and since there's no good place to put the motor, it's going to be a bit of a kludge.

I might give dual front hub motors a try....

 

[aronde]

I too thought long and hard on how best to convert my Christiania. I went for the rear hub motor and have not looked back since! Check out my blog in the signature block for all the details - the electric stuff starts from November 2009. Happy to answer any questions you may have!

 

[infviza]

I have just completed conversion of my Christiania bike (Shimano Nexus Inter 8 IGH) with Cyclone 250W single chainwheel kit. Will share some more details soon.

 

[aronde]

Hey infviza am looking forward to seeing how you went with the Cyclone on the Christiania! I also looked at that method but it seemed to be a bit of mucking around to mount it properly and it would have meant losing my Schlumpf Mountain Drive.

 

[Lessss]

Don't need to worry about a place to mount the batteries, THAT's FOR SURE!

 

[yuhr]

dwjp, how are you going to solve the wiring problem: standard kits are made for standard bikes, including standard length cables, e. g. battery to controller to motor cables. Your Christiania is much longer than standard 26" bike. Any ideas?

 

[dwjp]

Yep, these bikes are rated for around 100kg of cargo - that's alotta battery! That said, they aren't terribly aerodynamic, so I don't expect the w/km to be stellar.

Regarding wiring, it's no big deal either extending cables or making new ones, though I'll have to take some care that the voltage drop isn't excessive.

At the moment, I'm tending towards dual front 9C motors, and retrofitted disc brakes. That gives me regenerative braking, which might have some utility on a bike this massive, and means that all the wiring will be within the front box, and it won't be subject to any flex or wear.

I'm using this particular model, which is actually a Chinese knock-off of a Christiania...

It supports the front 20" wheels on both sides, while a real Christiania has the wheels attached on one side only - that limits your choice of hub motor considerably.

 

[zenon]

Hi dwjp

2) As above, but using a non-geared motor, which can use regenerative braking. Combined with the twin drum brakes up the front, hopefully this will provide enough stopping power?


No matter what you have to mod something in the trike to add electric assist anyway. I my experience modding the derailleur is the easy solution above all with 7 turn nine continent direct hub motor will allow 5 speed sprocket in a 134mm drop out. This will give you a good torque at 48v 35amp controller combo it might be overkill for your 15 -20km/hour goal but it will flattened the big hills for you if you have them in your area.

Two drums on the front is plenty of stopping power, most tadpole trikes comes with no rear brakes. But if you feel safer get a regen controller for the rear brake.

Zenon

 

[dwjp]

An update:

I went with two 20" NC motors up front, dual controllers off a single throttle, driven by a standalone cycle analyst (thanks Justin!) and 36V 15Ah Ping LiFePO4 Battery.

And wow, is it fun!

Having two motors doesn't seem to create any problems with steering. Indeed, if I disconnect one motor, I can travel quite happily with just the left or right motor operating, provided I keep a good grip on the handlebars. That's very reassuring to me -- if one motor fails, it isn't catastrophic. It meanders along, and flattens hill, at about 15-20km per hour -- perfect (I limit the current to ~15A). The regenerative brakes work fantastically, and I suspect will give me ~10% back. It still needs some disc brakes retrofitted to the front, but at moderate speeds the coaster brakes and regen suffice.

Tonight I'll test it properly with a box full of groceries from Costco. The whole conversion probably added ~15kg, which leaves me with 85kg of cargo carrying capacity!

Photos forthcoming once I give the thing a bit more polish (many loose wires at the moment).

 

[zenon]

Nice, Justin has almost exact same setup on his cargo trike, that thing can almost haul anything that will fit in the cargo area. The best cargo I've seen him haul were two ladies serving soft drinks at the Vancouver critical mass ride. :wink:
I taught that your trike is a single axle mount. Want to see some pic

Zenon