Help me pick some parts (please!)

[Arethosemyfeet]

I have a bakfiets.nl cargo trike and I'd like to fit it with an electric assist.

I'm looking for something that will be road legal in the UK (if at all possible), and a top speed of 15mph is fine.
My daily commute is around 6 miles each way and I'd like to be able to do that at around 12-15mph, so a range around the 20 mile mark under full load would be good. The route is mostly flat with a couple of hills that are steep but relatively short (if I'm in an energetic mood I can power up them without changing gear). The big issue is weather. I need something that is or can be protected against driving rain and 70mph winds and will still give me a boost (albeit not to 15mph!) even in those conditions. I'd like it to be able to help me to at least 6-8mph in those conditions rather than the 3-4mph I manage unassisted.
As I have a Shimano Nexus 8 hub gear on my rear wheel I want to fit a pair of front hub motors, preferably slaved to a single throttle, controller and/or battery. All my wheels currently have disc brakes.
I weigh in at around 180lbs/85kg, and the trike weighs around 40kg. I'm not against lead acid rather than lithium batteries, I'm already carrying a lot of weight so it won't make much difference. If I can get something that will give me a decent amount of low speed torque that would be nice, as I occasionally carry heavy loads.

I'd like to do all this under GBP900, but I'll stretch all the way up to GBP1200 and maybe beyond if needs be.

I realise I'm probably trying to get a unicorn here but I'd appreciate any advice you can offer.
EDIT: d'oh, forgot to mention that front wheels are 20" each, in 100mm drop outs.

 

[999zip999]

Li-ion, lifepo4 is all we advise.
Lead is an old Egyptian technology found in the tomb of king tut. A bad choice for ebike. Ok for a car starting battery. I don't have rain problems So. Cal. But a bafang middrive upgraded as the old ones had some bugs. Water proof ? 70 inches ?
Love those bikes saw one go 40mph the guy was from Oregon and took his kids to school. Check them out in the non hub motor section.

 

[Rassy]

I'd go for a Bafang 48V 500W BBS02 or something similar, a little over your "legal" limit but two hub motors would be also. This would make a great match to your Nexus and would allow you to adjust to your differing load and riding conditions without stressing your motor.

You could fix the "legal" problem with a sticker.

Good luck with whatever you decide to use.

 

[dogman dan]

We need to see your trike. It may or may not be possible to use front hub motors on it. It depends on if your front wheels fit in a fork, or if they have a solid axle that is part of the frame.

You might have to go rear hub, and then convert the bike to a derailleur gear, if front motors won't work well.



this pic of a bakefits is so small, I can't really tell if it's got a solid axle, or a fork with the axle part of the wheel.

 

[Arethosemyfeet]

The wheels are in (very short) forks and drop out independently.

Not a great pic I'm afraid but I hope it gives you the idea.

I'm hoping to get an upper limit on price from the manufacturers, as I've found out they will factory-fit a system like I want for around EU1300, and my importer is checking that with them.

Thanks for all the thoughts so far, really appreciated.

 

[d8veh]

That's not an easy bike to convert. You can't use a front hub-motor because you have two single-sided front wheels. You can't use a rear motor because you have hub gears and a coaster brake(?). There are modern middle motors that can work with the coaster brakes, but I haven't seen one yet. Give Wooshbikes in Southend a call as they have some new stuff. In the meantime, you need to check the width of your bottom bracket in case it's non-standard.

 

[dogman dan]

Looks to me like front motors could work, if the forks in front are 100 mm wide. Even just one front motor can work, odd as that sounds.

But I'm not certain about everything, how do the front brakes work? are those drum brakes? I'm pretty ignorant about bakefits, other than they are weird.

You might have to do something to add rim brakes, or disc brakes mounts to the frame.

Modifying the rear to rim or disc, and adding a derailleur gear could be easier. or not... a mid drive might be best, leaving only the rear brakes to sort out.

 

[Arethosemyfeet]

They are disc brakes, and I know front motors can be fitted because that's what the manufacturers offer, though I think I'll be giving their offering a miss at GBP1550! If anyone can point me to some sub-200W hub motors that would be a good start. It's looking like I might need to go a bit over the legal limit with regard to power unless I can find motors with less than 250W. If I have (say) a 250w 48 volt motor and run it at 36v, will it just scale down the wattage according to P=IV or will I just find the motor won't run?

 

[oobagooba]

wondering about your screen name...
https://www.youtube.com/watch?v=vh9mp_syc8c

 

[Asterix]

Crank drive is the simplest solution to convert this bike.
If you want a road legal crankk drive kit, your choice is limited at present to 8-Fun BBS01 15A 250W, widely available, or if you are in the EU, Woosh GSM 18A 250W kit, which has slightly stronger output. A few UK pedelecs forum members have fitted the GSM kit.

Reviews:
http://www.pedelecs.co.uk/forum/threads/fitting-the-gsm-kit.22477/
http://www.pedelecs.co.uk/forum/threads/gsm-crank-kit-from-woosh-and-charge-cooker-conversion.22479/

Woosh GSM:
http://wooshbikes.co.uk/?cdkit#gsmkit

 

[Arethosemyfeet]

My worry with a crank drive is ground clearance. They all seem to hang below the frame and I've grounded out a few too many times to be comfortable with that. I'm also a bit concerned about increased wear on sprockets and chains, as I already go through them fairly quickly (my mechanic, or rather my wife, starts to resent this after a while!). I shall have to give it some more thought. Thanks for the suggestions.

@oobagooba: well spotted!

 

[d8veh]

So you have disk brakes. That makes things easier. I thought they were hub brakes. You need to check the width between the front drop-outs to conform that they're the standard 100mm. If they are, you can fit a pair of Q100H motors. You'll need two controllers and a strong battery. As Dogman said, you can fit just one motor, but I think that one Q100H would be a bit weak and two would be better than a larger more powerful single motor. Have a look at all the threads on two wheel drive on this forum and on Pedelecs.co.uk.

You only need one throttle and one pedal sensor, but if you want to use the pedal sensor, the power control will be difficult. On a normal 2WD bike, you can use one controller for pedal sensor and both for throttle when you need extra power. The problem with pedal assist to both motors is that you need two control panels to set the power levels. It can easily be done, but you have to press two buttons each time you wanted to change the power, though, of course, you don't have to have the same power through each wheel.

You can get all the stuff from BMSBattery.com.

This battery:
https://bmsbattery.com/ebike-battery/445-36v-20ah-li-ion-shrink-tube-ebike-battery-pack-battery.html

These motors in 201 rpm and whatever wheel size you have:
https://bmsbattery.com/ebike-kit/632-q100h-36v350w-front-e-bike-motor-wheel-ebike-kit.html?search_query=q100h&results=5

The controller choice is tricky for the reasons stated above. For throttle and single level (full power) Pedal assist:
https://bmsbattery.com/ebike-kit/751-s-ku63-250w15a-6mosfets-controller-ebike-kit.html

For throttle and three level PAS with two control panels:
https://bmsbattery.com/ebike-kit/752-s-ku65-for-led810-250w15a-6mosfets-controller-ebike-kit.html

or with two LCD control panels. These make the motor much smoother and quieter, but you have to order the LCDs too, which makes them more expensive.
https://bmsbattery.com/ebike-kit/546-s06s-250w-torque-simulation-sine-wave-controller-ebike-kit.html?search_query=S06S&results=22

If you decide to go this route, make a shopping list and post it here because ther's a couple of other small items you have to buy, plus, we can check that everything is compatible.

 

[Arethosemyfeet]

I'm a complete novice at this, so forgive me if this is a dumb question. Am I right in thinking that the control panel and the pedal sensor send information to the controller which then directs the motor? If there any reason I couldn't just do a Y split on the cables carrying the signals to the controllers so that both controllers get the same signal? Or is there also feedback from the controller that the panel needs that would get confused by having two attached?

 

[Asterix]

you would need a lot of experience to make a two wheel front drive system. If for any reason, one of the two motors loses power, you will lose control of the bike's steering.
As a novice, your choice is therefore pretty limited, either a rear hub motor or crank drive. If you are not worried about a road legal kit, then you can consider a really powerful rear hub motor. Otherwise, only a crank drive makes sense.

 

[Arethosemyfeet]

If I were to consider some sort of mid-drive instead, are there any that won't have to sit below the chain ring and hence risk getting smashed when I ground the trike on someone's driveway? I'm a little concerned about shelling out £500-1000 only to smash the motor first time out. Or drown it in a puddle, which is also possible.

 

[Asterix]

I have not heard of an 8-Fun CDkit damaged because it hangs so low.
On my Specialized, the BBS01 is about as low as the bottom of my chainring.
The motor casing is also pretty solid.

 

[Arethosemyfeet]

The bakfiets frame goes forward horizontally from the bottom bracket. This forces any motor to sit below it, from what I've been told. As I've had to retouch paint on that bit of frame from grounding it (and seriously smashed up my pedals on other occasions), it's not something I'm keen to risk.

Right now I'm tempted to buy one of these: http://www.electricbikeconversions.co.uk/product/250w-front-wheel-including-downtube-lithium-ion-battery/
then figure out what I need to do to it to configure a second one. It doesn't look like I'm going to be able to get something road legal that does what I want, but this would at least keep me within the spirit of the law.

 

[Chalo]

So you have disk brakes. That makes things easier. I thought they were hub brakes. You need to check the width between the front drop-outs to conform that they're the standard 100mm. If they are, you can fit a pair of Q100H motors.

If both the front discs run inboard of the wheels (probably they do), then one of the hubs would have to run in reverse. That would preclude the use of a geared hub motor.

The dynamo hub would have to go, too. That's not too big a deal, because in this case we presume the availability of battery power to run lighting.

 

[Arethosemyfeet]

Thanks, chalo. I hadn't considered the direction of the motors. I take it that the gears in geared hub motors are one-way in some fashion?

 

[Chalo]

Thanks, chalo. I hadn't considered the direction of the motors. I take it that the gears in geared hub motors are one-way in some fashion?

Geared motors have a one-way clutch so they can coast freely. So for a front motor, that means the disc rotor must always be on the left.

 

[Ykick]

I believe we've had discussions that revealed some clutches can be reversed? Need to open the motor and I've never personally reversed the components but I'm fairly certain the Q128 clutch ramps I've seen can reverse the backing plate and flip around so that it can catch in the opposite direction?

 

[Chalo]

I believe we've had discussions that revealed some clutches can be reversed? Need to open the motor and I've never personally reversed the components but I'm fairly certain the Q128 clutch ramps I've seen can reverse the backing plate and flip around so that it can catch in the opposite direction?

Torrington type needle roller clutches can be pressed out (often destructively) and replaced in reverse orientation. I don't know if that is the prevailing type of one-way clutch used in hub motors, but the same should be true of CSK clutches and other discrete units.

 

[John in CR]

Do those types of 3 wheel bak fiets commonly have dual hubmotors up front? That would seem to cause some steering issues. You're looking for such low power assist at low speeds that a single tiny geared hubbie designed for higher speed use, but running outside the wheel and geared down could be a simple, durable, and quiet solution. There are also some very small direct drive hubmotors that would work too, and give you more freedom in how you add the electric assist to your pedal drive line. Motors like that are only about $100/ea and shipping is reasonable without being laced in a wheel. If you have multiple chain rings already, then the solution can be extremely economical, so you can invest in a nice big battery and still come in way under budget.

 

[Ykick]

Torrington type needle roller clutches can be pressed out (often destructively) and replaced in reverse orientation. I don't know if that is the prevailing type of one-way clutch used in hub motors, but the same should be true of CSK clutches and other discrete units.

I popped open one of my Q128 to have a look and the clutch is certainly reversible with a little rework. Here's a few pics...



Basically, flip the backing plate to the other side of the ramp assembly and it will engage the other direction. All the needed screw holes seem to be in the right location.

 

[Arethosemyfeet]

Do those types of 3 wheel bak fiets commonly have dual hubmotors up front? That would seem to cause some steering issues. You're looking for such low power assist at low speeds that a single tiny geared hubbie designed for higher speed use, but running outside the wheel and geared down could be a simple, durable, and quiet solution. There are also some very small direct drive hubmotors that would work too, and give you more freedom in how you add the electric assist to your pedal drive line. Motors like that are only about $100/ea and shipping is reasonable without being laced in a wheel. If you have multiple chain rings already, then the solution can be extremely economical, so you can invest in a nice big battery and still come in way under budget.

Dual hub motors is what they fit at the factory, I'm told it's a pair of 180Ws (giving total output of 250W). I can't speak to steering issues, but I would say that it's not a vehicle to corner with at high speed any way.