Looking for a lightweight hub motor with torque sensor

[schwibsi]

Hello everyone,

as I'm playing the conversion, I am going to do for my girlfriend, through in my head, I realized how many wires there will be needed for the install and how complicated it might get for her.

Wouldn't it be easiest and cleanest to get a relatively small and light hub motor for the back of the bike, that already includes the controller and a torque sensor.

No need for a cut-off switch on the brakes, no separate controller, no hall sensors.
Just one wire to the battery (bottle style mounted inside the frame triangle) and one wire to the switch to choose the level of support. (This switch could actually be wireless in my book, but not necessary.

I'm I wishing for too much, or does this maybe exists.
Budget is tight though, so a Bionix System or similar is out of the question.
I can spend between 200 and 300 Euros on the system without battery

 

[dogman dan]

Though likely required legaly where you are, I skip the brake cutoffs myself. The controller works fine if you never install the cutoffs. The switches that operate brake cutoffs can be located in places other than the handle though. along the cable on the frame for instance. Or just turn the brake cutoff into a kill switch.

Just a throttle wire to the bars is not so bad, but learning to use a throttle is hard for many. However, it seems to be best. Cheapo pedelec that just senses crank motion seems to be much worse and harder to controll than any throttle.

Bionix is what she'd like the best, but your wallet won't enjoy it.

The golden motor magic pie can have the controller inside the hub. It's not small, nor in the featherweight category. A small planetary gearmotor kit for the rear wheel remains the best bet for a light and freewheeling motor for assist.

 

[d8veh]

BMSBattery do a torque sensor and controller. I don't know if it's any good.
http://www.bmsbattery.com/ebike-parts/306-ebike-torque-sensor.html

 

[schwibsi]

I've seen those cheap crank torque sensors.
There are even more expensive versions such as boosty that support a quad chainwheel crank. But the one sold by BMS and others is not an option.

The Bionix system is indeed to expensive.
I found a chinese motor with a crank sensor installed on alibaba, but I was wondering if anybody had experiences in that area or other sources that I could actually affort. Bionix is out of the question, I'm afraid. If I had that kind of money available, I'd buy her a Bosch bike with a NuVinci N360 with an automatic shifter in the back. That's my idea of a fire and forget solution.... But at over 2000€ not something I can afford.

 

[motomech]

You are complicating things in your mind's eye when you need not.
Go to the Photos and Vid.s section and look over some of the builds. No dangling wires or gizmos hanging off. The build is as neat as the installer wants to make it.
Just because the motor kit photos show a mess of connectors and wires doesn't mean they all have to be used. A minimal install will only have a few wires being routed and a front motor mount doesn't even need for the wires to run full frame. Besides, how is a few neatly routed wires going to confuse your girlfriend? She doesn't have to interact with those. Give her some credit.
As for the crank sensor, another problem that doesn't exist. A sm. geared motor on 36V and 14 Amps comes on very smoothly and in conjuction with a half-twist throttle[I prefer left side], the application of power becomes very natural. As one applies more to the pedals, one just leans a little more on the throttle/grip, very intuitive.
I think most of here, even with modest componates, wouldn't trade for a Bionx[except maybe to sell it and buy more DIY stuff}.
Get her a sm. motor kit from Cell_man or BMS Battery, she will love it.

 

[schwibsi]

Already contacted Cellman to see, what we can do.

The wires will only disturb her as far as the optics are concerned. It's not that she wouldn't understand it.
About the throttle, and the brakes. She has a very weird handlebar, were you attach things from the middle and the brake and gear levers are integrated.
So, if I change the brake levers, I will also have to get new gear levers.
She has Shimano 3x7 gears in the bike.
What's a sm motor?

I'll probably get one of those from Cellman. He's already told me what kinds of batteries he makes. Let's see, if it's possible, to get a removable one for her frame.

 

[dogman dan]

That seems to be an actual torque sensor, but you want the version for 36v, presumably on another page.


Usually cheap pedelec is just a crank rotating sensor. Half a turn and Woah, who asked for full throttle? No big deal when you are limited to 250w perhaps, but put it on a 15 amp controller and you might be looking at a sudden unasked for 500w. Many hate it.

But this seems to be able to vary the controller imput based on how hard the rider pedals, like bionx. Might be perfect for you.

 

[schwibsi]

Bad news.. They told me, they ended their cooperation with the japanes motor manufacturer and do not have that motor anymore.

So unless somebody can tell me another source for a motor with a torque sensor, I'm going with the system Cell Man recommends.

The dream would be 500W, 36V under 4kg and torque sensor. I think then I could die happy

 

[motomech]

Already contacted Cellman to see, what we can do.

The wires will only disturb her as far as the optics are concerned. It's not that she wouldn't understand it.
About the throttle, and the brakes. She has a very weird handlebar, were you attach things from the middle and the brake and gear levers are integrated.
So, if I change the brake levers, I will also have to get new gear levers.
She has Shimano 3x7 gears in the bike.
What's a sm motor?

I'll probably get one of those from Cellman. He's already told me what kinds of batteries he makes. Let's see, if it's possible, to get a removable one for her frame.

Cell_man is very well respected here, and so are his batteries. But they are not a budget packs. They offer a high "C" rate, the ability to discharge a lot of power quickly, something she really doesn't need. Still, better to have too much battery, than not enough. BMS Battery offers a "lesser" chemistry battery, at considerable savings, but once committed to a vendor, one needs to get everything from that vendor to consolidate shipping costs.

The motor you want is a small geared motor, we call mini-motors. The one Cell_man offers is a MXUS and it comes with a 17 Amp controller. It is the largest and most powerful of the Mini's.

With Cell_Man's 39V battery, this would be a great runner, easily hitting 21-22 mph.
But is this what she needs,...probably not.
I recently received a couple of mini-motor "Kits" from BMS Battery and although I haven't installed them, I impressed with the quality for the money.
One of them is this kit,
http://www.bmsbattery.com/ebike-kits/420-250w350w-q-85100sx-motor-e-bike-kit.html
The motor is even smaller than the MXUS, a good thing for an install with Hyd. brk.s. With the MXUS, I had to spend time "clearancing" so the brk. rotor wouldn't hit on the motor.
The tiny controller[a little larger than a pack of cig.s]is rated 14 Amps. There are two winds[motor speeds] for these kits. The "slow" wind, called a 201 wind, combined with a 36V Li-on battery would top out around 18 to 19 mph. The faster wind, the 328, would be a few mph faster.
At the risk of being condescending, I would do something I don't usually do and recommend the BMS Battery Kit over Cell_Man's, as I think it would be better suited to your "better half".
Details to simplify things,
Q100 36V "slow" wind kit. I would recommend the frt. mount kit if the fork allows it. At this power level, the handling will be fine and you won't have to change her cassette to a free wheel.
36V LI-on battery, either rack or pack, depending on mounting options
Don't order the torque arm from BMS Battery, they are a poor fit. You want one like this,
http://www.ebikes.ca/store/photos/TorqArmRev3.jpg
A half twist throttle like this should work with her existing controls,
http://www.ebikes.ca/store/photos/T-HTwist.jpg\
With the money you have saved, treat her to a Cycle Analyst,
http://www.ebikes.ca/drainbrain.shtml

These last three items are from the Ebike CA store, but I believe there is a supplier in Europe. Pedectic UK would be able to tell you.
Lastly, the Ebrk levers. You need not use them. D8veh has detailed the use of a simple reed switch than he adapted to the existing brk. system. You can search his posts with keywords "reed switch", or he will probably be back here and link you to it.

EDIT-I just noticed the kit I linked to now has a half twist throttle as an option, so you could give it a try. I suspect the throttle I linked to is of better quality. I prefer the left side model as I am shifting on the right[most here do not shift the front derailuer]. These are hard to find, the only one in stock right now that I know of is from Lyen[member here].
Here is my MTB with a MXUS on the frt. I am not all that fastidious, but I managed to hide everything fairly well. The controller is a larger, more powerful model and it is stashed in the mesh pocket of the frame bag. Not obvious, but still getting some air circulation.

 

[schwibsi]

Thanks for all that effort Momotech. I really appreciate it.

I just wrote to BMS for a quote for 2 of the sets you suggested, with 2 bottle style 8.8Ah batteries.
Shipping costs seem way off.
I feel that 8.8Ah is a little on the short side. I'd feel more comfortable if it were 10 or even 12.
But having a removable battery to me is key, as the bike will be stored in a room, where there is no power outled and I want her to be able to quickly take out the battery take it up to the appartment, and leave it in the charger until the next time she gets on the bike.

The CA is absolutely awesome and at some point I will definitely become a customer of Justin's but right now, increasing mobility at minimum cost is key, and "luxury upgrades" will follow latter.

Do you know the difference between "A twist grid throttle or a Half Twist Throttle or a Thumb Level Throttle"?
As she has one of those weird handlebars shaped like a circle, where you mount the brakes etc. from the middle, a grip throttle is out. I could mount a thumb throttle, but anything else would mean me having to cut into the foam.

I have 3 more questions.
Is the thumb throttle spring loaded and it goes back to zero, once it is released, or does it stay in the position it was?
Is there a way to implement a cruise control, some sort of a button to press and the bike stays at the set speed?
Does the throttle control the power output or the targeted rpm?

 

[schwibsi]

Oh, and one more question:
Should I try the torque sensor in the crank?
Does anyone have experience with that?
She has a 3x7 Shimano STX.
With the power of the motor she might not need the front derailleur. Then I'd get rid of one of the brake/shift levers and install a one of the BMS-ones instead.
Might be worth looking into.

 

[motomech]

QUOTE-"I just wrote to BMS for a quote for 2 of the sets you suggested, with 2 bottle style 8.8Ah batteries.
Shipping costs seem way off."END OF QUOTE

If one of those kits is for you, you might want to make it a "fast" wind.
In the final stage of placing your order, they will recalculate the shipping. If you still think it's out of line, contact them. It could have to do with shipping batteries.

QUOTE-"Do you know the difference between "A twist grid throttle or a Half Twist Throttle or a Thumb Level Throttle"?
As she has one of those weird handlebars shaped like a circle, where you mount the brakes etc. from the middle, a grip throttle is out. I could mount a thumb throttle, but anything else would mean me having to cut into the foam."-END OF QUOTE

I think the "Twist grid throttle is a full Motorcycle style throttle.
I have used 3 styles of thumb throttles and dis-liked all of them. The best of the three is the one Cell_man sells, as it goes horizonaly, but it has the stuoid LED meter on top that takes up space.
I'm not sure what you mean by "circle bars", but there has been one rider who adapted a half twist to a set of drop bars. What he did was add an extension[short stub]vertically near and in front of the grip so the throttle hand grasped it like a joy stick. It was very slick, but I don't how I could find the thread. Perhaps someone else here remembers who it was.

QUOTE-"Is the thumb throttle spring loaded and it goes back to zero, once it is released, or does it stay in the position it was?
Is there a way to implement a cruise control, some sort of a button to press and the bike stays at the set speed?
Does the throttle control the power output or the targeted rpm?"-END OF QUOTE

They are spring loaded, some of them fiercely so
There are several ways to have CC. In your case, the easiest is to upgrade to the 9-FET controller when you place your order. One holds the throttle steady for 6 to 8 seconds[adjustable]and it engages. This IS where the ebrk. switch is needed to dis-engage, although a "blip" of the throttle will do the same. But these are higher Amprege controllers and will make the systems more powerful and power hungery. D8veh really likes these controllers, so once again, don't do anything till he comes back, as I'm sure he will have some good ideas.

A note about ordering from BMS Battery. Once you place an order, the only contact you will receive is about payment. Then, about 10 days later when you are sure they have forgotten you, you will receive a trackin # and your goods soon thereafter. At least that is how it was for me.

 

[schwibsi]

Here are two pictures of the weird handlebar.

By schwibach at 2012-05-24

By schwibach at 2012-05-24

This should pretty much explain, why those grip levers are not too practical.

Can this switch not be used for the cruise control?
http://www.bmsbattery.com/ebike-parts/54-thumb-level-throttle-with-battery-meter-and-a-switch.html
I'm thinking in the lines of setting the throttle with the thumb throttle and locking it with the switch.

Will the brake levers play nice with the Shimano XT V-brakes I got her for Easter?

 

[d8veh]

The shipping cost from BMSBattery seems expensive compared to the cost of the goods, but when you add the two together, the overall cost is vey cheap.

The KU63 controller is set for about 14amps, but I always solder about 30% of the shunt to take it up to 18amps for better hill-climbing.

I wouldn't advise the high speed (393rpm) motor for a 26^ wheel because it would not be working in it's efficient range. It's for a 16" wheel.

You can use any switch as a cruise control. You can mount a 10k pot as a speed selector wherever convenient and then switch it on/off with the switch. I mount my pots in a little 25mm cube plastic box from Maplin that I zip-tie to the handlebars. Here's a photoo of mine on LH handlbar before I put a knob on it. My switch is mounted on the side of the box if you can't slide on that switch that you showed.

or you can use the thumb throttle that has a switch on it to switch between the pot cruise control and normal throttle. That's how it is on this bike. Here's a diagram of how I did it,

 

[schwibsi]

It doesn't say, which controller the kit comes with, do I have to order the KU63 separately?
I've seen that there is a nice little case, you can buy for it... might be nice to attach it just under that handle bar.

I'll get back to you on the switch and the cruise control once I've ordered the kit. I'll order a switch from BMS and the poti etc. I'll get from a DIY electronics store here. Good to know it can be done easily.
I'll also ask some more about "chiptuning" it to 18 Amps. I've soldered a few things, so with proper guidance I feel capable of doing it.

It's actually not 26" but even 28", so I guess I really should go for the slow wind.

Actually, you know what, if the new cycle analyst is already available, I might get one now, because she'll want a speedo anyway, and the CA will let me take a good look at what's going on exactly.

The rims on her bike aren't exactly round anymore, so I'm thinking of either getting the motor installed in the rear wheel with their 7-speed cassette and ordering a front wheel without a motor, or getting the motor in the front wheel and buying a new wheel with a 7-speed cassette for the rear.
Which brings me to the question of whether to get her the disc brakes they offer. It might be practical to get both wheels from BMS with disc brakes installed and using their brake levers.

The XT brakes would get passed on to our soon to be 7-year old, who could also use the upgrade. The V-brakes in the front of his 20" aren't helping much anyway.

I'm also thinking, it might be a good idea, to reduce the effective costs, by getting some extra batteries and selling them on ebay.

 

[d8veh]

The 250w motors come with the KU63 unless you get the kit with the little handlebar panel. The controllers are so cheap that you can get another one as a spare anyway because the shipping doesn't cost any more. You can also get one of each throttle type to try which is best.

Don't waste your time with that little case. It's virtually impossible to fit the controller in it without shortening the wires and removing the connectors. The frog battery is quite neat because it has a compartment for the controller underneath and makes a neat installation. Also two zippy 8000maH 6S lopo packs are a snug fit in one of those cases, which makes a cheap powerful battery, but you need extra stuff and a bit more hassle for charging.

I'd always advise to get the wheel fully built by them. It saves a lot of hassle, but they're not very good at tightening the spokes, so you need to check and tension when it arrives. Also. you often need to dish the wheel a little to get the rim central - more so for disk brake versions. Building the wheeel yourself is only for the more discerning people that need specially strong or expensive rims, or who simply like to do it their way. It adds a lot of expense if you get someone else to do it.

With 28" wheels, it has to be the 201rpm motor.

You need to check what your current gearing is. You'll spend a lot of time pedalling at about 15mph or more, so, as an example, 44T chainwheel with a 14T rear top gear will be a bit to low (too fast pedalling). If you have 48T chainwheel it might be OK, but you might be better getting the 11T free-wheel set from ebikes.ca rather than the 14T one from BMSBattery.

I think I'd go for a rear motor so that you don't have to replace both wheels. They're so light that the weight of the motor and battery doesn't make a lot of difference.

Don't get one of those bottle batteries if you want to run at 18amps. Several people have reported that the're a bit weak and only good for about 12 amps. You need a battery of at least 10aH unless you go for lipos or A123 cells.

If you need any help with installation, or any of the other points, post again when your stuff arrives or send me a PM.

 

[dogman dan]

Re the throttle, thumb or half twist throttle will work fine on those bars. Personally , I much prefer the half twist, but thumb is still ok for shorter rides. I just like the half twist for rides 15 miles or more. Some of the foam on the bars will have to be cut back for a throttle. If you remove it carefully, it could be replaced later if the bike will be restored to original.

Do beware of too small a battery with a too big controller. At a minimum, you want to have 1 ah for every two amps. Better, 1.5 ah per two amps of controller. An 8 ah bottle battery would be best with a 12 amp or less controller. 12 amps x 36v = 432 w. Enough to barely cruise at 20 mph no pedal. But pretty weak on a steep hill.

 

[schwibsi]

She also wants a twist throttle So, end of discussion there

BMS is a little difficult as it's quite hard to talk to them. They wouldn't really answer my questions or even quote me properly.

I asked for a rear wheel kit incl- disc brakes and an additional wheel for the front with the same disc brakes installed and they referred me to the online shop, where you cannot select that.
Also, other technical questions were left unanswered, which, if it already happens in pre-sales, usually is a bad sign.

I don't know why, but I have a good feeling about the Cute Q128.
If there were a kit with 2 of the smaller Cute motors with a controller for both, that might be an idea, but my mind is drifting off again.

I agree, the low C rating of the BMS 8Ah bottle style battery is a nogo for anything above 250W.

I have to be honest, a nice looking, quickly removable battery with a mount in the frame is a must. Anything attached to the rear rack or a fiddly solution on the frame will not make her happy.
I've seen some other manufacturers of bottle style batteries that have a holder that can be attached like the bottle holder. They go up to 12Ah.
If the discharge rating allows for it, I would rather get her 2 smalller batteries (8-10Ah) than one 12-15Ah battery as 90% of the time, she'll go on trips shorter than 20miles. For anything longer than that, she could bring the second battery.
I would prefer to keep the bike lighter for her. Also she would always have one fully charged battery in the garage, no matter what she's been up to. (Very important for a person, who's phone's empty at 10 in the morning because she forgets to charge it over night)

Dogman, I've seen the Frankenbike, you've built, with the frame mount you've made, and she will not ride the bike if it's anything like that. She's a real girl when it comes to those things and just wants it to be pretty.

BMS also sells these bottle type battery cases:
http://www.bmsbattery.com/aluminium-alloy/234-bottlle-battery-case-for-cylindrical-cell.html

Is there maybe a cheap way to get some Cells a BMS to put in there? Then I'd make us a few of these packs.

 

[motomech]

You are wandering off track

She also wants a twist throttle So, end of discussion there


BMS is a little difficult as it's quite hard to talk to them. They wouldn't really answer my questions or even quote me properly.

I asked for a rear wheel kit incl- disc brakes and an additional wheel for the front with the same disc brakes installed and they referred me to the online shop, where you cannot select that.



Also, other technical questions were left unanswered, which, if it already happens in pre-sales, usually is a bad sign.

I don't know why, but I have a good feeling about the Cute Q128.
If there were a kit with 2 of the smaller Cute motors with a controller for both, that might be an idea, but my mind is drifting off again.

I agree, the low C rating of the BMS 8Ah bottle style battery is a nogo for anything above 250W.

I have to be honest, a nice looking, quickly removable battery with a mount in the frame is a must. Anything attached to the rear rack or a fiddly solution on the frame will not make her happy.
I've seen some other manufacturers of bottle style batteries that have a holder that can be attached like the bottle holder. They go up to 12Ah.
If the discharge rating allows for it, I would rather get her 2 smalller batteries (8-10Ah) than one 12-15Ah battery as 90% of the time, she'll go on trips shorter than 20miles. For anything longer than that, she could bring the second battery.
I would prefer to keep the bike lighter for her. Also she would always have one fully charged battery in the garage, no matter what she's been up to. (Very important for a person, who's phone's empty at 10 in the morning because she forgets to charge it over night)

Dogman, I've seen the Frankenbike, you've built, with the frame mount you've made, and she will not ride the bike if it's anything like that. She's a real girl when it comes to those things and just wants it to be pretty.

BMS also sells these bottle type battery cases:
http://www.bmsbattery.com/aluminium-alloy/234-bottlle-battery-case-for-cylindrical-cell.html

Is there maybe a cheap way to get some Cells a BMS to put in there? Then I'd make us a few of these packs.

Yes, A nice half twist throttle is a key element. When I was using a thumb throttle, I longed for C.C. Now, I don't even think about it.
I will go against what D8veh recommended and stress a frt. mount. What we only touched on is the free wheel. With a chain ring of 44T or smaller, you will be required to go with a DNP free wheel if she wants to pedal at speed. I have one sitting next to me here on the desk for my next build and I am lothe to use it. It is a heavy. crude, pile of scrap metal. They are also known to be glitchy, noisey and prone to rusting. The only reason anyone here uses them is that it's the only free wheel available with an 11T sm. cog. I will be modifying mine before I use it.
Bms Battery wheel builds are adequate, nothing more. I think you would be better to repair hers or find a used one than to go with a rear mounted motor as a wheel solution. With a frt. mount, the entire back half of the bike remains untouched. Priceless.
You are aware that the BMS Battery Brake kit is mechanical, right? And that the discs are larger than her wonderful XT units? They are really for those mounting big motors and require larger discs to clear the motor housing. So you will need cables and adapters and in th end they will not work as well as her Hydro.s. Giving a good XT system to a 7 yr. old is a waste, I.M.O. :lol: The beauty of the Q100's is that they easily clear the rotors, so you would be throwing that perk[along with the ease of frt. mount away].
BMS Battery has always been incapable of answering techincal questions. That's why most just get the basic stuff from them and order the fancy parts from someone else.
The Q128???? Now you are really getting off track. The Q128 was the first of the Cute mini's and is wide. All bets are off concerning fittment and clearing the brk.s. Also, recent reports have come in the the Q128 has suffered some down grading of parts quality. If you are attracted to that motor because of it's[on paper]higher power handling, you should have stayed with the MXUS from Cell_Man.

Don't be mis-led into thinking that Alibaba bottle batteries have more capacity than the one BMS Battery offers, they are all the same. It does have enough capacity to easily handle 36V/14A. Go to the Amped Bikes site's forum and check out the scores of builds using the MXUS[mostly frt. mounts] and the bottle battery. There were early problems with that battery, but I believe they have been rectified.
I agree that she will be most happy with the "look" of the bottle battery, so buy two for her.
My bottom line recommendation,
Buy the basic kit[why do you need two?] and batteries from BMS Battery and everything else can be sourced from other vendors sooner or later.
Worry about cruise control latter, if she thinks she needs it. I use a thick rubber o-ring in the gap between the throttle and the grip[or in her case, the foam. Workss great. Remember, the CC's that we are talking about only maintain power, not speed[with the possible exception of the CA or the up-coming revised CA].
Use the stock controller. If she feels she needs more help for climbing latter, you can mod the shunt a few Amps[more power consumpsion, nothing for free]or buy another that you can have custom configured from someone like LYen.
If you take my advise and go with a frt. mount, show us a pic. of her forks. Still, you should get a nice Ebike CA torque arm for the initial install.

 

[d8veh]

Just to make it clear, I'm not saying that a rear motor is better than a front one. Personally, I have no preference. I have two of each: one of each low power and one of each moderate power. I reckon that they both have advantages and disadvantages for both installation and riding, which make them more or less equal. For a powerful motor and heavy battery, you don't want to mount them both at the rear because it upsets the handling of the bike. The point i was making is that for a small motor and lightweight battery, you can fit them on the rear without it upsetting the handling. As OP needs to replace the back wheel, and if you agree that all other things are equal, then it would make sense to fit a rear wheell motor. I use a 11T free-wheel set on one of my bikes and I don't see any problem with it. I got it from Cyclezee.com in the UK, but I'm guessing that it comes from the same source as Ebikes.ca because there seems to be links between the two suppliers.

@Shwibsi. When buying stuff from BMSBattery, don't order anything non-standard. They'll get confused and send the wrong stuff and you'll be stuck with it, plus it'll delay your order. Just order stuff from their on-line shop. If you want a matching front wheel, order the rim and spokes and learn how to build the wheel yourself - doesn't take long. You'll have to calculate the length of the spokes using one of the on-line calculators. Be aware that if you add larger items like rims or additional heavy items to your order, their shipping cost calculator doesn't allow for it so you'll get an e-mail from them when they're ready to ship demanding an extra $22 or so.

 

[schwibsi]

Here are a few pictures I just took.
On a German forum I offered the guys to organize a group order from BMS. The same goes for anyone here. If I can order for them, too and forward the items, just let me know.

Thanks for getting me back on track. I tend to get "distracted" by a seemingly optimal solution.
I wasn't aware of the freewheel being a worse solution than the cassette.
In that case, I agree in that it would be better to install a lightweight motor in the front rather than the rear.

She will have to pedal along at speed. In Germany you cannot build an ebike that drives without pedalling (It would be considered a motorcycle etc) so it should at least look like the motor is only there to assist.
I would like her to be able to ride at 30-35kph on the flat, but while pedalling at somewhere around 70 rpm.
From what I read on the internet the largest chainwheel the STX has, is a 42T and the cassette in the back ranges down to 12T. If my math skills don't betray me and I calculated, she'll do about 26 kph (with an estimated 2.1m circumference of the wheel), pedalling at 70 rpm would result in around 30 kph. Sounds perfect.

About the brakes. The XT- V-brakes I got her are also mechanical, but my feeling is that the cantilever levers installed don't really work for it, Too much play until the brakes grip. Also, due to the ancient wheels installed, I'd feel much better, if she had the disc brake at least in the front with the fitting lever. But I'm wondering if it is even possible to install disc brakes. Doesn'T the fork have to fulfill some sort of requirements for that?

I still have another 28" wheel with a 8-speed cassette and a rear 8-speed derailleur lying around. Also, an XT- gear lever for a 9-speed cassette. Hmm... If the other wheel is ok, I might get her a 8 speed gear lever and be done with the repairs.
But I'm going off on a tangent again.

So, what do we do? Get her a Q100, half grip twist throttle, 2x bottle style 36V 8.8 Ah batteries and be done with it? Or is there a way I can get/make a better battery with the same kind of mount but more power output.

By the way, the second kit would be for my bike to play around with and see, what it'd to for me. My frame is a lot larger than hers, so anything that fits in hers will go in mine aswell. And if I'm already paying the enormous shipping costs, I might aswell spring the additional 100€ for a motor for myself.
I'll have to buy a couple of extra batteries and sell them over ebay anyways to make the whole thing affordable.

 

[motomech]

Yes, I have both photos on file, I was considerating a BPM build and I was using them for comparision.
I guess the pluses and minuses could go on and on, both we might agree on this. Your BPM frt is at about the max[1100 Watts?]of what's safe to run up frt. and at 600 Watts or below, there is little difference in the handling. Which makes a low-powered mini an Ideal canidate.
I just think folks dis-miss them out of hand.
But in this case, if I understand the OP,
1]she loves her bike the way it is and
2]it has decent componates
All the more reason to leave as much alone as possible.

 

[motomech]

Here are a few pictures I just took.
On a German forum I offered the guys to organize a group order from BMS. The same goes for anyone here. If I can order for them, too and forward the items, just let me know.

Thanks for getting me back on track. I tend to get "distracted" by a seemingly optimal solution.
I wasn't aware of the freewheel being a worse solution than the cassette.
In that case, I agree in that it would be better to install a lightweight motor in the front rather than the rear.

She will have to pedal along at speed. In Germany you cannot build an ebike that drives without pedalling (It would be considered a motorcycle etc) so it should at least look like the motor is only there to assist.
I would like her to be able to ride at 30-35kph on the flat, but while pedalling at somewhere around 70 rpm.
From what I read on the internet the largest chainwheel the STX has, is a 42T and the cassette in the back ranges down to 12T. If my math skills don't betray me and I calculated, she'll do about 26 kph (with an estimated 2.1m circumference of the wheel), pedalling at 70 rpm would result in around 30 kph. Sounds perfect.

About the brakes. The XT- V-brakes I got her are also mechanical, but my feeling is that the cantilever levers installed don't really work for it, Too much play until the brakes grip. Also, due to the ancient wheels installed, I'd feel much better, if she had the disc brake at least in the front with the fitting lever. But I'm wondering if it is even possible to install disc brakes. Doesn'T the fork have to fulfill some sort of requirements for that?

I still have another 28" wheel with a 8-speed cassette and a rear 8-speed derailleur lying around. Also, an XT- gear lever for a 9-speed cassette. Hmm... If the other wheel is ok, I might get her a 8 speed gear lever and be done with the repairs.
But I'm going off on a tangent again.

So, what do we do? Get her a Q100, half grip twist throttle, 2x bottle style 36V 8.8 Ah batteries and be done with it? Or is there a way I can get/make a better battery with the same kind of mount but more power output.

By the way, the second kit would be for my bike to play around with and see, what it'd to for me. My frame is a lot larger than hers, so anything that fits in hers will go in mine aswell. And if I'm already paying the enormous shipping costs, I might aswell spring the additional 100€ for a motor for myself.
I'll have to buy a couple of extra batteries and sell them over ebay anyways to make the whole thing affordable.

I mis-understood, when you said XT brakes, I was thing XT Delore hydros. Why not look around for a frt. sm.rotor disc brk. for the frt. and leave the rear Vbrakes. I see caliper mounts on the frt. but not the rear. Most of the braking is with the frt. anyhow.
QUOTE-"I still have another 28" wheel with a 8-speed cassette and a rear 8-speed derailleur lying around. Also, an XT- gear lever for a 9-speed cassette. Hmm... If the other wheel is ok, I might get her a 8 speed gear lever and be done with the repairs.
But I'm going off on a tangent again."-END OF QUOTE
Yeah, but in a good way this time :wink: All that makes sense to me. You can play around with the ratios. If there is room around the chain stay, I believe you can fit up a 44/46/48T frt. They are available for 4 bolt patterns, both 106mm and 110mm.
http://www.jensonusa.com/Salsa-4-Bolt-Outer-Chainring

46/48 X 12\13 would all be decent to pedal @ 35 Kph. With a motor, even a sm one, most don't shift the frt. derailuer. Eventually, you might want to get a half hand twist throttle to free up the right hand for indexing the rear.
As for you, you need to do this of course :lol: [from Pedelecs Germany]

http://translate.googleusercontent.com/translate_c?hl=en&prev=/search%3Fq%3Dcute%2BOR%2Bananda%2Bq100%2B328%26hl%3Den%26client%3Dopera-portal%26hs%3D5lT%26channel%3Dportal%26prmd%3Dimvnsfd&rurl=translate.google.com&sl=de&u=http://www.pedelec-forum.de/forum/showthread.php%3F1309-S-Pedelec-mit-Dualantrieb/page12&usg=ALkJrhjNkgsdZiTkE9EiS_DCPi3vMFoD0w

He does some nice 2WD build with mini motor, one with dual Q100's

 

[schwibsi]

@d8veh

Ok, Gotcha, nothing fancy from BMS!
I have seen videos on youtube of guys building wheels but I didn't think it was a real possibility for regular people. But I am willing to give it a try. I take it, the lenght of the spokes will depend on the hub and the spoke pattern (and the wheel diameter of course)
Do you know any good tutorial, that I could use?
Would I need any special tools?

@motomech
The bike is my baby sister's old bike, which hadn't been in use anymore. It was a decent very light weight bike then, and I'm still surprised at how little it weighs. I exchanged the brakes and the tyres and some other minor components to make it road safe. It's not like they have a history together.
The only way I could get her to even try riding a bike was the promise of both ice cream and sex in one day.
The motor is meant as an additional incentive for her to really use it to go to work with it every day and go on little trips with me and the little one.

On the brakes: I agree, if a front disc brake is doable, I would opt for that.

On the crank: The way I see it, she's shifting very little as it is right now, it will be even less so with the motor. So I think she's not going to need the 3 gear crank anymore. So, the torque sensor BMS sells comes into play, but it only has a 42t chainwheel. 42t imho is not enough for comfortable pedalling at speeds of 30-35 kph. I agree, 46 or 48t should produce a better result. Is it possible to upgrade that crank to a larger chainwheel? The gear range of the rear derailleur should then be enough. Would that be a possibility?

You mean the dual build could be something for my bike or hers? Actually, I have a N360 in the rear of mine, which I absolutely love despite the trouble it gives me sometimes, and I wouldn't want to give it up. I could do without some of the extra weight, but it's just amazing, not being giving a set number of options for the gearing of the bike, but actually being able to set the bike to the exact ratio to want at any given moment. Priceless!

So, disc brake mount in the front of her bike is possible?
Do I need anything besides what they include in the BMS kit?

Are we agreed on a Q100 in the front and 2 sets of bottle style batteries for her?
Which controller does the Q100 come with? Should I get another one in addition to that to try?

 

[motomech]

@d8veh

Ok, Gotcha, nothing fancy from BMS!
I have seen videos on youtube of guys building wheels but I didn't think it was a real possibility for regular people. But I am willing to give it a try. I take it, the lenght of the spokes will depend on the hub and the spoke pattern (and the wheel diameter of course)
Do you know any good tutorial, that I could use?
Would I need any special tools?

@motomech
The bike is my baby sister's old bike, which hadn't been in use anymore. It was a decent very light weight bike then, and I'm still surprised at how little it weighs. I exchanged the brakes and the tyres and some other minor components to make it road safe. It's not like they have a history together.
The only way I could get her to even try riding a bike was the promise of both ice cream and sex in one day.
The motor is meant as an additional incentive for her to really use it to go to work with it every day and go on little trips with me and the little one.

On the brakes: I agree, if a front disc brake is doable, I would opt for that.

On the crank: The way I see it, she's shifting very little as it is right now, it will be even less so with the motor. So I think she's not going to need the 3 gear crank anymore. So, the torque sensor BMS sells comes into play, but it only has a 42t chainwheel. 42t imho is not enough for comfortable pedalling at speeds of 30-35 kph. I agree, 46 or 48t should produce a better result. Is it possible to upgrade that crank to a larger chainwheel? The gear range of the rear derailleur should then be enough. Would that be a possibility?

You mean the dual build could be something for my bike or hers? Actually, I have a N360 in the rear of mine, which I absolutely love despite the trouble it gives me sometimes, and I wouldn't want to give it up. I could do without some of the extra weight, but it's just amazing, not being giving a set number of options for the gearing of the bike, but actually being able to set the bike to the exact ratio to want at any given moment. Priceless!

So, disc brake mount in the front of her bike is possible?
Do I need anything besides what they include in the BMS kit?

Are we agreed on a Q100 in the front and 2 sets of bottle style batteries for her?
Which controller does the Q100 come with? Should I get another one in addition to that to try?

I have seen videos on youtube of guys building wheels but I didn't think it was a real possibility for regular people. But I am willing to give it a try. I take it, the lenght of the spokes will depend on the hub and the spoke pattern (and the wheel diameter of course)
Do you know any good tutorial, that I could use?
Would I need any special tools?

It just takes patience and a spoke wrench. Check out the Sheldon Brown website.

On the brakes: I agree, if a front disc brake is doable, I would opt for that.

I think I miss-spoke on that. Looking a the photo more closely, those nubs are not caliper mounts. I've seen those before, something plugs into them, but i forget what. I have zero experience with V-brk.s, but there have been posts here concerning V-brk. up-grades. Appearently, some higher end V-brk. systems can be made to work very well.

On the crank: The way I see it, she's shifting very little as it is right now, it will be even less so with the motor. So I think she's not going to need the 3 gear crank anymore. So, the torque sensor BMS sells comes into play, but it only has a 42t chainwheel. 42t imho is not enough for comfortable pedalling at speeds of 30-35 kph. I agree, 46 or 48t should produce a better result. Is it possible to upgrade that crank to a larger chainwheel? The gear range of the rear derailleur should then be enough. Would that be a possibility?

I'm no bicycle expert[and it's starting to show ], but there are ways to get a bigger chain ring on there. I took my bike to the local shop and asked the guy if I could fit a 48T. he said he had a spacer that goes on the bottom bracket[spindle?]that would move the chain rings out far enough to clear the chain stay.
Really, for the brk.s and gearing, I think it would be best for you to research and use local sources, local shops, clubs, etc.
I went for a ride today, mostly on back streets and even with suspension, things can get quite bumpy above 20 mph. I could well be, that in the end, you will find that 30 Kph is enough and the brk and gearing issues will not be issues at all.

You mean the dual build could be something for my bike or hers? Actually, I have a N360 in the rear of mine, which I absolutely love despite the trouble it gives me sometimes, and I wouldn't want to give it up. I could do without some of the extra weight, but it's just amazing, not being giving a set number of options for the gearing of the bike, but actually being able to set the bike to the exact ratio to want at any given moment. Priceless!

No, I was just kidding about the 2WD. But I really like that German Ebike forum and Nader's builds in particular, although much is lost in the translation. If you read German, it would be a wealth of info. At any rate, that link should give you ideas about controller placement. etc.

Are we agreed on a Q100 in the front and 2 sets of bottle style batteries for her?
Which controller does the Q100 come with? Should I get another one in addition to that to try?

Yes, I think so.
The kit comes with the Ku-63 controller. You might order the inexpensive KU-65 as an extra. It comes with the LED display, while not very accurate, would give some idea of how much battery is left. Or/and the half twist throttle w/ led for $5. Spare controller and thottle for only $27 extra, good idea. I would still recommend the CA when you can, but the latest version is not ready and it might be worth waiting[I haven't read the entire thread about that, but I think Justin is doing something along the lines of making a true PAS work with it. That would be the best PAS solution.
Another, less expensive option for a "fuel gauge" is a Watt meter[Watt's Up]. It would need to wired in series with the power wires, but if you placed the controller in a sm. mesh bag, hung from the H.bars, the wires would already be there.
Lastly, Although the BMS Battery torque arms won't work up frt. with disc brk.s, they should work well enough on her simple fork. Order those as well.
There is also the possibility of mounting both batteries, certainly it could be done on the larger framed bike. That way, when the first battery ran out, the second one could be plugged in and then it would be time to head home. Speaking of the batteries, the pic doesn't show what connector it comes with. One would think BMS Battery would match them up, but to be on the safe side, get two of these, for 20 cents
http://www.bmsbattery.com/connector/394-dj7021-63-11.html
To encapsulate, start simple, adjust bike componates as needed[don't buy a lot of stuff that you may not use]and save for the new C.A.
Actually, just save, these things are addicting :lol:

EDIT, FYI, Casainho is exploring the KU-63 controller every which way, inside and out. I'm not sure why, but there it is, "Everything you ever wanted to know about the KU-63, but were afRaid to ask."

http://endless-sphere.com/forums/viewtopic.php?f=3&t=38337