Building a Kona Ute cargo/commuter bike

[miuan]

Hi folks,
thanks for lots of useful resource over here.
This is my first post so plese be patient with me for some time.
I have done road, mountain XC and DH races before, so I have been using pretty much all kinds of bicycles over the past 25 years.
Recently I picked a Kona Ute 700c wheeled cargo bike which I love so much for its shopping and commuting ability, and still being a piece of art itself, turning a lot of heads (including mine). I can easily get it to 30kph on windless straights and climbing is also no big issue, you just feel the extra weight. The frame gets some flex from strong pedaling under high rear load (more than 20kg), but I can cope, being 75kg myself.
PIC: MY CUTE KONA UTE (note I added chrome mudguards, lighting, bell, horn etc...)
As you see the bike has a lot of space for battery / controller and still carries a lot of goods.
To be able to do longer shopping and commuting routes (40-50km), I decided to get a LiFePo4 battery and a decent hub motor, preferrably between 250 and 500W. I want to stay away from chain drive for the extra noise it produces and the aesthetics, of course. I want to keep the build as classic as possible, no nerdy visible parts if possible.
My aim is to keep pedaling as much % of saddle time as possible. The terrain is not very hilly over here, but there are some sustained 1-2km climbs, if not too steep (max. 8%). There are also some short 12%+ climbs, but I am ready to help extensively during these. My idea is, if I can master these steep climbs at 9kph, so adding a motor should help me get to 15-18kph, which is the minimum speed that I require the motor to run at. However, being able to run 30kph with my human power means that I'd like the hub to be able to get to 40kph comfortably with my pedal assistance = 48-50kph with no load w/ 700c wheels.
After some forum and market research, I decided to buy either a Bafang or Cute 350W/36V motor from BMSBattery.com (good seller?) and run it at 48V. Thus I don't have to use full throttle/amps at high 30kph's w/ easy pedaling, and power will be high enough with a 25A controller on those steep climbs at 15-18kph with moderate pedaling + WOT.
I'm probably going to order 2 hubs plus some replacement nylon gears, in case anything goes bad and China happens to be too far from by bike that particular day.
First question: Are my maths OK? I assume the hubs will do 50kph with no load and 700c wheel, and a 25A controller (delivered with the hub from BMSBattery)
Second: Are the hubs durable enough to withstand such V/A loads and last thousands of kms? I believe so, though the Cute's don't have any track record yet.
Third: Front fork is a Kona P2 steel. It could bear a lot of abuse and run these motors safely, keeping my bike better balanced (much load in the rear already), but still I prefer the rear motor for traction and safety reasons. Is the rear Alumimium dropout OK for the 350W motor?
Fourth: As already mentioned, I carry 30-40kg load in the back from time to time. Is the Bafang / Cute axle going to be fine under this load?
Fifth: There is a known issue with rear Bafangs where the threaded cassette flange would separate from the hub under high pedaling loads. Is there anything I can do to avoid this failure? I guess it is vital to keep the chain as close to the hub as possible, thus lowering the lateral torque.
Many thanks to all replies!

 

[dogman dan]

I think you have the right track there, except for the wattage. 48v(56v hot off the charger) x 25 amps gives you 1400 watts of peak output. Don't worry about it though, the Bafangs at least are proven to be ok at 48v x 20 amps. And that will be enough power to get you moving at the speeds you want, and get some heavy weight up hills ok. The gearmotor will keep it light, and allow freewheeling when you don't want to use the motor. I have a similar motor from Fusin that has amazed me with it's ability to take abuse. For a 20-25 amp controller you will want a decent battery, for example a pingbattery in the 15 ah size. Other types of lifepo4 with higher c rates could use a smaller size. A 48v 15 ah would give you range in exess of 20 miles at full speed which can be really nice. Being too range limited is a drag so spend enough on the battery to have a really usefull ebike.

I think front hub would be the way to go, actually giving you better traction. You aren't going to run into bad traction effects on a front hub till you get a lot more power or a lot steeper hills. But cornering with pedals grabbing on the rear tire, and motor grabbing on the front is sweet! Don't knock having the front wheel pulling you trhough a corner till you try it. For maximum stealth, hiding it all behind the bags on a rear wheel is best though. But even on my most obvious front hubs, 90% of people that I talk to think it's some kind of drum brake.

If you plan on some real long haul riding, then you need a much bigger motor to take the heat. The same may be true if your climate is really hot. Small gearmotors have the tourqe to pull a big cargo bike, but push em too hard and they will get very hot. I'm allways beating that drum since I live in a hot climate. Under 70F, motors shed heat fast enough under even tough use. But over 90F you need to consider motor heating to ride longer than 10 miles, or climb a lot.

See the reviews and testing section for more info on the motor's I've tested such as the Fusin, and a thread on comparing motors on hills.

 

[miuan]

That was exactly the kind of answer I was looking for. Thanks for the thumbs up Dogman!
Note that the weather isn't overly hot here, and in favour of motor longevity, I can give up some wattage - could a 15-20A China controller be enough? I believe it only affects the steep climbing ability, and I am OK with this - moderate pedaling in the steepest of climbs goes a long way for the battery / overall heat too.
At the price I may as well buy two different controllers, just in case.
As for battery, I was sure planning a 15-20Ah battery. A Good range is what I want.
I will reconsider the front motor. No problem with the aesthetics, I only wish I can fit a 160mm disc, because the P2 fork has no rim brake mounts!

 

[dogman dan]

Amps and wattages are hard to give advice on. I like to pedal, expect to work on the bike, and just want help so I can climb easier and travel faster. So to me a 48v 20 amp controller seems to have plenty of power.

Others get disgusted that the motor slows to 10 mph on a steep hill, or when hauling 100 pounds of extra weight. I think it sounds like a 48v 20-25 amp controller will give you enough help. Upping the ante to 35 or more amps is nice but may cause you to nearly double the cost of the battery to have one that is big enough, or high c rate enough to handle that 35 amp discharge rate.

On the other hand, below 20 amps, things get pretty weak. My Fusin gearmotor is 36v 15 amp, and up very steep hills or into a lot of wind it just chokes. The same bafang like motor running on 48v 20 amps performs a lot better I'm told. But the guy with that bike is about to switch to a much bigger stronger motor. Why? Because he hauls a heavy trailer, and climbs steep hills. So my best advice is to try a decent gearmotor at 48v 20 amps. If that is too weak, then most other motors at 48v 20 amps will be also, and you will need to go to a huge motor that will be too heavy for riding around unpowered at all. The cost of a good battery with lots of range for such a motor can be $1500 and up. So trying out a much cheaper system, say $1200 for everything including the battery makes sense. Much depends on how far you plan to ride. Much more than 10 miles in warm(95f) weather gets most motors real hot, and heavy loads will make that worse. If you plan on riding far, using the motor continuously then a big heat sinking heavy 5304 is what you want. But even 5 miniuites of pedaling without power can cool a gearmotor quite a bit. Wierdly, pedaling or coasting on a direct drive hubmotor makes just as much heat as running the motor.

For disk brakes, Ebikes ca sells an Ezee kit that is disc compatible. Ezee is a gearmotor so it has the freewheeling quality you want. I think the BMC gearmotors are disk ready too.

 

[jag]

However, being able to run 30kph with my human power means that I'd like the hub to be able to get to 40kph comfortably with my pedal assistance = 48-50kph with no load w/ 700c wheels.
After some forum and market research, I decided to buy either a Bafang or Cute 350W/36V motor from BMSBattery.com (good seller?) and run it at 48V. Thus I don't have to use full throttle/amps at high 30kph's w/ easy pedaling, and power will be high enough with a 25A controller on those steep climbs at 15-18kph with moderate pedaling + WOT.
I'm probably going to order 2 hubs plus some replacement nylon gears, in case anything goes bad and China happens to be too far from by bike that particular day.
First question: Are my maths OK? I assume the hubs will do 50kph with no load and 700c wheel, and a 25A controller (delivered with the hub from BMSBattery)
Second: Are the hubs durable enough to withstand such V/A loads and last thousands of kms?

As an alternative, how about one 9C? Unlikely you need a backup, since there is little to break on the DD motor. I think it will be better able to handle the sustained power at your desired 40km/h. FYI: At 50km/h I'm putting 800-900W into my 9C. This is fine with the 9C but would likely shorten the life of a Bafang or Cute. I don;t remember a precise figure for 40km/h, but I suspect it is in the 500W range. Now form me pedalling or not does not make a huge difference at these speeds to the Watt readings on the CA. The power to overcome drag is simply so much higher than my pedalling input (guess 100-200W?).

 

[miuan]

ould likely shorten the life of a Bafang or Cute. I don;t remember a precise figure for 40km/h, but I suspect it is in the 500W range. Now form me pedalling or not does not make a huge difference at these speeds to the Watt readings on the CA. The power to overcome drag is sim

Hi, no I don't need to travel at more than 40kph unless I go downhill. Above this speed, the aerodynamic drag is too high to ride effectively and yes, any pedalling would not contribute enough anymore. This and also in my area, there is no need to travel at more than 40kph fast due to the roads. My aim is what Dogman proposed - have a motor that helps me when I can't pedal well enough, make me faster on the straights and provide me with a big range. If ~500W is all I need to go 40kph without pedalling, I'm sure I don't need anything more, at least at this point of time. I also plan to pedal a lot without any assistance at all, actually leaving the battery at home. That's why a DD motor would not suit me well. As for the gears, I'm sure that 500W at 40kph minus 100W (my input), or even without it, will be okay for a 350/500W bafang/cute and I will keep them running for a long time.

 

[dogman dan]

Yeah but if you run 48v, then you have a 10 amp controller to stay in that 500 watt range. My fusin gearmotor with the 36v 15 amp controller is pretty lame on a hill. So your reallly are talikng about 750-1000 watts, hitting 1000 when you use a 48v 20 amp controller. You'll need the higher wattage to get up any steep hills. In cruising mode, on flatter ground, the motor will draw less, perhaps 600 watts. What will save the motor is the intermittent nature of the use you plan on. Even short rests of 5 min or so will allow the motor to cool a lot. This doesn't work with direct drive motors like a 9c, because a dd motor will continue to make heat when coasting with the power off. On a dd, you have to actually stop for the motor to cool. Slowing down can help, but only makes the motor make less heat, or heat slower. So if riding without the power on is the plan, a gearmotor is definitely the thing.

But if I was building the bike, I'd use a front 9 continent motor and 48v, and run the motor all the time. A 48v 20 ah lifepo4 would give you lots of range. I get plenty of pedaling and extend the range by setting the throttle to a certain speed, and then pedaling to go 1-2 mph faster. This puts the motor into it's most efficient power band. The 9c has lots of power to haul up a hill, and great heat shedding surface area, and can use a disk brake.

One thing though, bear in mind that even with the batttery off, you will be packing an extra 20 pounds or so on the bike with the motor on, so ride around with 20 pounds on the bike first to see if you really will be doing ANY pedaling without the motor. With the battery, add another 20 pounds. You may very well be better off to go with an Ebikekit 9 continent and a 48v 20 ah pingbattery. You may want to ride motoring 100% of the time on the cargo bike, and then have a light road bike for pedal only, non cargo trips.

 

[miuan]

Most of my trips are non-cargo. When I pedal with cargo it is doable, however some help from the motor is definitely desired.
If I decide to go human powered, I will leave the battery at home and only carry those extra max. 6-7kg for motor and accessories, which is not so bad. Is it really 20 pounds for a 3-4kg motor plus controller, wiring and throttle/switches?
I now think about getting the Cute 350-500W motor from BMSBattery, and also a 48V20Ah battery which uses thin high capacity 20Ah single pouch cells. Dimensions are 0.7 x 17 x 25cm and weight ~500g each. BMS integrated or external, battery form customized, duct tape or raw in my option. Anyone familiar with the quality?
9c motors can be found cheap too, but they are direct drive, aren't they?
PS: I have 3 other bikes, so enough time left to pedal, no need for a road bike

 

[miuan]

OK, did some research and found the 9c rh205 kits pretty cheap on http://www.wheelkits.it
I am starting to lean towards 100% motor use and some pedalling as a bonus, it is a cargo bike anyway and a DD motor pretty much kills any pure pedalling.
However, while I know I would choose the medium gear option (I believe it is NineCont2806 on ebike.ca), now I am stuck at whether to buy front or rear motor - though the site only offers this hub for rear, but maybe I'll find a front hub elswhere.
Running a front wheel with a big motor like this will draw too much attention. Anyway I doubt the cops would mind, as the very same hub has also been certified in EU at 250W.
Running a rear wheel motor will be stealth enough, but with a big motor like this, and a big battery plus cargo, the rear end will be super heavy, plus I will only have limited cogset choice. And I need the 11 teeth lowest cog I have now!!!
Finally, which end of my bike will tolerate the 1000W peak output of this hub better: The kinda flexy aluminium rear triangle, on a steel P2 fork upfront?
I kinda wish I'd run it up front, because I could pop the front wheel out anyday and go for a human powered ride with my current front wheel and w/o battery. And the bike would be better balanced too. But horror stories about forks keep my fingers crossed.

 

[mrzed]

Have you ridden on a DD hub motor? My 9c does not "kill" pure pedaling. I can easily maintain 28kph on level ground with moderate effort. Basically knocks 2-4 kph from my speed on the same bike without the hub. Similar in additional drag to going from slicks to knobbies on the road.

I'm running the same motor at 650watts on the front. Installed properly, I think you are better off with a front kit at 1000w. Going much beyond that, I would defer to the extreme types here who tend to favour the rear install.

I think throwing everything on the back would be a safety hazard from a handling perspective alone.

Absolute key is proper install, and that goes no matter what end of the bike it is on. The reason the front install is more critical is what happens if the motor does get loose (very bad things). Then again, this is no different than losing a front wheel on any bike, which is ironically why we have these stupid lawyer lips that make it harder to safely install a front hub motor.

 

[miuan]

Yeah I pretty much agree. The only problem with front install on a Kona Ute is that my fork has no rim brake studs, and at the same time, the 9c motor has no disc mount. However, I may try to use screw-on studs from another fork, and drill them into the P2 fork.

 

[dogman dan]

Mabye I'm confused, and maybe it's the rear ones only that have it, but I thought you could get screw on disk mounts for the 9c.
None of my bikes are disk, so I've not paid much attention to this.
edit, Yup, the 9c is disc compatible only in the rear hub. Fitting a new fork with rim brakes is an option, but then you end up with a bike of many colors.

I find my 2807 9c pretty tourqey at 36v. It goes about 20 mph top speed so maybe you can find what you want easier in that winding.

With direct drive there is some cogging resistance, sorta like a brake dragging. My 9c and my aotema don't cog too noticeably, till you get on the fusin bike with no cogging a feel the difference. My big 5304 cogs like hell, and would never be ridden unpowered for very far.

It's hard for us to give good advice, since we don't know how strong you really are, but 90% of ebike riders use the motor 100% of the time that is not downhill. It's just nicer to go fast, and todays lithium cells make carrying a huge battery easy. So we just motor all the way and get there faster. So direct drive works great for lots of us. If you like pedaling, as I do, you just pedal faster till the effort level is to your liking. You will still need your highest gears, believe me! I have a 58 tooth front sprocket on my commuter.

 

[miuan]

These are the kits from http://www.wheelkits.it that I'm considering at the moment:
Medium power RH205 high speed 2806 rear hub which equals to [http://www.cnjzdj.com/e_ProductShow.asp?FItemID=181]this[/url]
The same as previous but stronger controller and 'only' medium speed wound 2807 hub - more than enough speed for me - ideal if it was the front one.
Weaker and smaller FH154 front hub which equals to this - I'm afraid this will be too weak/slow in comparison with above mentioned.

Unfortunately, it seems 9c front hubs don't accept discs and this seller offers no 2806-2807 front hub kits at the moment, which is a shame. Importing a set from ebike.ca is tempting for the added CA, but assuming $150 shipping to Slovakia and 22% import taxes on top of it, that's 475€ in comparison to less than 250€ for any of the above mentioned kits incl. shipping.

As for my stamina, being a hobby MTB racer and a young lad still, I think I can pull quite a lot. I also have a 48T chainring which should be OK until 50kph, provided I manage to fit a 11T rear sprocket. However my intention is to use throttle 100% time as you suggest, and pedal hard only once the massive 48/20 battery cuts off, or during a traffic light takeoff, to be the pack leader 8). This will be my commuter and shopper primarily, moving on roads a lot, and most of the time I will prefer to stay away from sweating. So I fear that the smaller front motor may really slow me down. I don't really care about high mileage, but if I do, I can still pedal / ride slower and farther, no matter the controller or motor power rating.

So what do you think? Will the bigger rear motor with 27A controller cause me much trouble during the ride? I don't really look forward to getting around the front brake/hub/fork incompatibility, even if I manage to find the bigger front motor somewhere else. Finding a 5-6 sprocket cassette with a 11T ring will also be difficult though.

As for the 9c downsides, is noise the only thing I should fear? How about durability...

 

[mrzed]

9c noise is nothing to fear - unless you are worried about your ability to sneak up on cats.

It ranges from a light growly sound with low speed/high torque, to a light tinny ringing at higher speeds, in all cases not very noisy - you would be hard pressed to notice it in city traffic. Other cyclists on the trail rarely notice mine by the sound.

Durability - better than any geared motor on principle, but that is something that only time can tell, and they have only been produced for what - 2 years? Ebikes.ca has a high opinion of the QC on them, and that was good enough for me to order.

 

[jag]

Running a rear wheel motor will be stealth enough, but with a big motor like this, and a big battery plus cargo, the rear end will be super heavy, plus I will only have limited cogset choice. And I need the 11 teeth lowest cog I have now!!!

You can put batteries in the triangle up front to get better balance with a rear motor. See:
http://endless-sphere.com/forums/viewtopic.php?f=4&t=9549

You can also fit a regular 7sp freewheel. 11tooth ones are available. My 9C came with 2x3mm thick inner torque washers, and I spread the frame 10mm to accomodate these + an additional 4mm washer. However, I don't think you need the washers. If you forego (or use thin) inner washers you only need to spread the frame a mm or two. (And some people have found and fit 7sp freewheels for which no spreading is needed. I would get the kit from Italy. There might be more resellers of 9C kits in Europe as well. I think someone posted one in Germany not so long ago.

 

[dogman dan]

Yeah, get the 9c wheel, and go ahead with a rear one. As said above, you can balance the bike some by carrying the battery up front, but really, cargo bikes are built for packing a lot of weight in the back, so it won't be as unbalanced as a MTB carrying the same load. Buy it where it's cheaper, but be ready for it if the wheel has an alignment issue. Some vendors here in NA have had some problems with 9c rear hubs having a funny dishing. So you might need to get creative with spreading the dropuouts and using some spacers to get the alignment right. We have no idea if your supplier is using the same dishing we had problems with or not. Apparently they (9c) were supplying rear hubs dished for some chinese ebike frame that was different from regular bikes. All that was last year anyway, so it may not be a problem with your supplier at all, but you might want to ask about it.

Forget about the fast winding motor too for a cargo bike. Speed is great, but on a cargo bike you need tourqe, and when pulling hard, efficiency. A faster wind will make more heat than motion when really loaded down getting weight moving. So the fast motor is going to waste your batterys energy, and in the process heat the motor more than you want as it struggles to get started. Think in terms of the speed a 2807 9 contininent goes at 36v. So 35 kph at 36v or 40 at 48v. That is right in the sweet spot for 48 tooth front and 14 rear gearing. So a common 7 speed cluster with a 14 tooth on the small one will work fine on the cargo bike. The 2807 is what I'd want, and in fact the next motor I want to buy is a rear 2807.

As for the controller, the issue is whether the battery can take what the controller dishes out. Hill performance and start ups will be improved a lot by a 35 amp controller, vs a 20-25 amp. But if you climb a long hill, or ride into a lot of wind, or just have a lot of weight on the bike, the 35 amp controller will put a lot more strain on the battery. So for the big controller you will need a lot of amp hours of battery to keep the discharge rate on each cell low. So for most lifeop4, nicad, sla's ect, you will need 20-30 amp hours. Better cells, like the headways, could do the same work with 10 ah size.

With a 20 amp controller, you could use a nice light, and cheaper 48v-15 amp lifepo4 or nicad battery.

It's a lot to consider, since you want a setup that does more. We may seem to have a lot of changing ideas, but as a newbie, It's hard for you to really understand what the ebike is like. As your understanding increases, you start to change your end goal. Lots read about somebodies hot rod bike that cost $3500 and then get real dissapointed with what the one they paid $700 for can do. But actually the cheapie does a lot, it just doesn't accelerate very fast, or climb a really steep hill very fast.



The fast wind motors are best used on a faster lighter bike, that doesn't have to stop often. Then they can really fly, and stay in the efficient speed zone for the faster motor. So thats riding in the open country with no cargo. Maybe later you can get a second motor to put on another bike and use the same battery for both.

 

[dogman dan]

Browsing on the wheel kits website, the all around 800 watt, 27 amp kit is what I'd buy. The other option in 26" rear wheel is only a 17 amp controller. I like my 9c a lot, with a 22 amp controller, but I doubt I'd be impressed with the 17 amp.

The batteries on the site are a really poor match for the 27 amp controller though, unless you buy two of them to have 20 ah of size. The 10 ah lifepo4 is usualy best for 15-20 amp controllers, not 27. 3c discharge rate, or 30 amps will kill a 10 amp fast. Two batteries paralell connected would be a 20 ah pack, and have 30 amps at 1.5 c.

 

[Drunkskunk]

I love a good Kona! Thats a nice looking bike.

I believe Dogman and I run the same speed 9C, the 9X7, which is sometimes refered to as the 2807. He runs the front while I run a rear motor. In reality, its a 500 watt motor, but I think that site has it listed as an 800 watt motor. 36volts, 22 amp controller has a max of 800 watts.

Rear mounting makes sense for a cargo bike for the same reason rear wheel drive makes sense for a cargo hauling truck: you want the power delivered under the weight. The bike is already unballanced when you seat your 75kg self on the seat, at the rear of the bike. Adding the motors weight to the front won't dramaticly change that balance. Mostly, though, its a matter of taste.

Aluminum dropouts on a Kona rear axle are fine. You'll need a torque arm to keep from spinning the axle, but they are strong enough to support the thrust. I'm running 3000 watts through my Kona Stinky (diffrent motor), it holds up fine.

36 volts gives me 36kmh on flat, smooth ground and no headwind. It reliably gives me 32kph over average road surfaces, a little wind, and low hills. I weigh 80kg. Pedaling with the motor is no problem.

 

[miuan]

Yeah I love the looks and ride of my Kona. A Mundo may be stronger, but it's uglier, more expensive (paid 500€ for my new Ute) and all in all not exactly what I'm after. I never load more than 40kg, and barely ride off road. The rear end is definitely flexy under heavy pedaling, but I can cope. Also when I install the motor, no heavy pedaling will be needed, ig any. Big wheels with big tires are nice too - I never feel my bike is too tall, and dig the off road performance of a rigid bike like this. The only downside is the bar shape. While it looks classic and works fine for the daily commute, it's been a couple of times in 300km when I found myself losing control over unexpected bumps because of the crazy backsweep and my hands falling forward through the grips. I changed the stem for a 120mm Kore which helped position my hands better. A suspension fork would be nice too since I will buy a rear motor, but I feel a flatter bar would be an easier fix for me, having ridden them on my other MTBs for yers.

After some playing with ebike.ca simulator, I too decided to choose the high torque 2807 motor - the slowest of the three listed 9C motors: 2805, 2806 and 2807. I entered the following values: 700c wheels, 16S Ping battery (plan to buy a 20Ah one from Ping or BMSBattery) and a 25A controller (27A included in the 800W kit, or 22A in the 500W kit). With various throttle settings, the motor provides almost any desirable speed with appropriate power rating. 80% throttle should serve me well at 38kph and 90% gives me 45kph. A 65% throttle will be enough for 32kph and a 70km+ range I believe. All of these within 80%+ motor efficiency, no wind, no hills and no pedaling, though on paper only.

Anyway I am still confused. Drunkskunk says he has a 9*7 motor, but the 9*7 motor is said to be "High speed" on the italian site, while they say the 7*9 motor is "Allround" and the 6*10 motor is called "High Torque", which should be the one I'm after. I will contact the seller to clear this up, but I need to be sure about what X*Y config to ask for at first.

Last but not least, I'd probably want to stick a capacitor onto the controller to save the battery at peak loads, but even 2C peak load should be no problem for a cheap but good LiFePO4, hopefully. Correct?

 

[dogman dan]

Now I'm confused, but anything I said pertains to the 9x7 or 2807 motor which is the one I am testing now. My kit has the 22 amp controller.

36v with a pingbattery is acually 40-44v. Some voltage sag when pulling max amps too, but not a ton of it, so 40v is a good number to work with. On a startup, pulling 22 amps, thats about 880 watts. Cruising, pulling 12-15 amps depending on how hard I pedal, 480-600 watts. So calling that setup a 500 or 600 watt motor is fair enough. Run it on 48v, actually about say 56v on a ping. Then you have 840 watts in cruising mode, pulling 15 amps. Even that wattage is a bit weak for a really heavy cargo bike going up a steep hill, but normal shopping type cargo will be no problem with 22 amps 48v.

Wouldn't 2805 be the fast winding? 5 turns? and the 2807 be the tourqe one? 7 turns of wire? In any case, I would choose the 9x7 for a cargo bike unless I was going to deal with some really steep hills. Not carrying cargo, my 9x7 climbs up a 7% grade pretty nice with no pedaling at all compared to my other two motors. At 36v too. I guess I should put on a 50# pack and repeat the hill testing, but for now, no thanks. Maybe I could have a fattie ride up the hill for me. see the review section for the hill test thread.

Edit, duhh, now I get it. In Eruope you have the 20kph speed limit in most places. So a 9x7 would be considered a fast motor under that law. To stay legal, and still have enough amps to even get up any hills, you would have to use much slower winding motors to use a 20 amp controller and stay legal. The 9x7 at 36v is going to go about 30-35 kph. The 9x7 has good tourqe, enough to have to be carefull not to spin the tire all the time starting with a front hub. The other motors won't really have that much more tourqe, but will hit that efficient fast cruise part of the curve on the simulator at a lower speed. For increased tourqe increase amps if the battery can handle the increase.

That may have been a confusing paragraph. To stay legal, under 20 kph, you could either use a weak controller or a slower motor. With a weak controller, hill performance would suffer, say a 10 amp controller vs a stronger performing 22 amp controller. So to use the 22 amp, and remain legal, they use a slower winding like a 9x10 instead of a 9x7. Here in the US, we have a speed limit around 32 kph so we consider the 9x7 the slow, high tourqe, legal motor. Again, the tourqe of all the motors is really pretty similar, but the efficeint cruising speed at full throttle is different.

 

[Drunkskunk]

Edit, duhh, now I get it. In Eruope you have the 20kph speed limit in most places. So a 9x7 would be considered a fast motor under that law. To stay legal, and still have enough amps to even get up any hills, you would have to use much slower winding motors to use a 20 amp controller and stay legal. The 9x7 at 36v is going to go about 30-35 kph. The 9x7 has good tourqe, enough to have to be carefull not to spin the tire all the time starting with a front hub. The other motors won't really have that much more tourqe, but will hit that efficient fast cruise part of the curve on the simulator at a lower speed. For increased tourqe increase amps if the battery can handle the increase.

Yeah, that makes sense. Over here, the 9X7 is our slow hill climbing motor, but for the Europeans, it would be the Hot Rod under there laws. the 6X10 would be 30% slower, but have a little more torque and better efficancy while climbing.

The way those numbers work is confusing. the 9 in a 9X7 means the number of strands used in each winding, essentualy, a useless number for comparing motors. Interesting, but useless. The 7 Is important though. Its the number of turns of copper around the coil. A Higher number will be slower, a lower number is faster. And its almost linear. a motor with 5 turns is almost exactly as fast as a motor with 10 turns, like the 6X10.

what that means is a 6X10 is 30% slower than a 9X7, but would have a little better efficancy while climbing. However, were this gets interesting is when you increase the voltage. with 30% more voltage, the 6X10 will be as fast as the 9X7, BUT will have 30+% more torque.
So if you run a 6X10 at 48 volts instead of 36v, you'll still go 30kph or more, but with 30% more climbing power.

 

[miuan]

So the 2nd number is important for speed, gotcha. I'm going for the 9*7, a 6*10 or 7*9 would be too slow. I definitely want to reach 40kph and more unassisted on straights.

So in your opinion, this motor:
http://www.wheelkits.it//index.php?mypage=12&ID=30&lbSelect=
which the seller designates as "High speed" and is the fastest of the 3 option he offers,
is the very same motor that ebike.ca lists under 2807 in their simulator, and is actually the slowest of the 3 motors offered by the simulator? Seems strange to me.

raf242, am I assuming correct? What is the no load RPM of the 6*10 motor you offer?

PS: today I went out with 15kg extra load and did some climbs. No problems. I think if I can pull 9kph at steep hills, the motor will take me to 15 and more with enough torque. At this speed, I'm hitting 50% efficiency. May seem little to most, but I haven't got a lot of such climbs near my home, and the ones I have and not longer than 1/2 mile. So I can get away with higher battery drain, especially considering I plan to buy a 20Ah LiFoPO4 pack.

edit: Hey Dogman, obeying limits is not my aim at all!

 

[miuan]

OK, I studied this and this thread, and it is now clear to me that 9*7 is 2807 as Dogman said.
2807 is the slowest 9C motor in ebike.ca simulator, and oddly enough, the "High Speed" motor on your site at the same time. So I basically have 2 options:
"High Speed" - 2807 - 9*7
or
"Allround" - 2809 - 7*9

The "High Torque" 6*10 is really not an option for me. I know I have a cargo bike, but both me and the 48V LiFe are fit enough to pull it in the steeps, and I'm sure I would miss the top speed (6*10 would only give 35-40kph).

Having toyed with the calculator a lot, I again decided to take the 2807 over others. With the 27A controller kit I can reach speeds of 45-50kph on level ground, which is just enough for my bike anyway, and the steep climbs will be fine too with ample 570 Watt max. power available at 15kph. Hope the motor can take loads of 1200-1300W. It's sold with the 27A controller anyway so warranty should fix any problems. 22A option could be OK too and is cheaper, but why settle for less when I invest hundreds in a big battery...
Maybe it's narrower as it hasn't got disc mount, so I don't need to stretch my frame... Raffaele could you please verify this?
Or, maybe you can also combine the non-disc wheel with a 27A controller.

 

[dogman dan]

Drunkskunk rarely posts anything wrong, but my impression is that you won't be needing more tourqe than a 9x7 at 48v can provide, especially if you opt for 27 amps on the controller. Hills less than 1/2 mile long are quickly over even if steep enough to need some brisk pedaling. You will be able to go op 7% grades at 20 kph without pedaling on the 9x7, as long as the load in the panniers isn't too heavy. With 48v you should have top speeds around 40-45 kph. But your motor can be ridden efficeintly at any speed. Simply set a speed on the throttle, and pedal till the bike goes a few kph faster. This puts the motor into the lower power use zone that is very efficient extending range. It only takes a moderate effort to do this, and even the steepest hills can be climbed in this manner. Oddly, a really steep hill can be climbed very efficiently by slowing way down, pedaling briskly, and using only a tiny bit of throttle.

Whether you have a need to bend the dropouts may depend on the alignment of the wheel, how it's dished. This was a problem here for awhile, but has been resolved with the US vendors. raf242 should be able to answer that question. Does your rear wheel align ok with a normal bike? With 135mm spacing?

If you get the 27 amp controller, make sure you get a battery that is up to 30 amp continuos discharge. For most of the lifepo4 battery types, that's a 20 ah size battery. You want the bigger battery anyway so you can have long range. You should get around 50 k range at 35kph with a 9x7 and 48v 20 ah battery. Double that if you slow down to half the speed.

 

[miuan]

Taking the 9*7 27A kit and hopefully a 48V/20Ah battery, once Mr.Ping answers my e-mail
I will keep you posted as my build evolves.
Thanks to all!