Author Topic: Installing an electric mid-motor  (Read 18166 times)

Andre Jute

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Re: Installing an electric mid-motor
« Reply #15 on: June 21, 2015, 02:58:49 PM »
wow - thanks for all this Andre.

It turns out I was wrong about Bafang being Sunstar's supplier. Quite the contrary: Sunstar has sued Bafang in Germany for copyright infringement! So it looks like (allegedly -- heh-heh!) the Bafang could be the Sunstar design, with improvements; no wonder the first thing I notice is visual and constructional and specification similarities statistically quite some way beyond coincidence. What this also very likely tells us is that Sunstar doesn't have a real torque sensor (as on the Bosch-Panasonic bikes) because if they did, Bafang would have copied it with the rest of the design. I think it is safe to conclude the Sunstar "MMC solid torque sensor" is a virtual, chip-based, generated-in-software approximation rather than a direct torque measurement, exactly as in the Bafang.

Some of the Bafang improvements (Sunstar may not call them that...) are very small but to my mind very important. For instance, Bafang has found a way of doing away of locating the motor so that it can't rotate without the crude bent tab, and the paintwork-wearing stay to the frame of the Sunstar.

It turns out (not clear from the ETS site) that the Sunstar is a new model - 36V motor, new battery system and a new LCD display - which may explain the higher price.  

There's more about the upgraded Sunstar SO3, called the Vertus, at http://www.sunstaribike.com/en/new-36-volt-sunstar-s03-and-lcd-display/.

I'm about 40 miles from Cambridge and Whoosh bikes have a store there so I can check out the BBS as well as the Sunstar.  

They have good photographs of the Bafang BBS at http://www.wooshbikes.co.uk/?cdkit but from the description it appears their kits are the limited ones. Ask them about reprogramming the Bafang kit for you before delivery. I couldn't find the new Sunstar Vertus type on their site. Ask them if the Sunstar has throttle operation independent of the pedals.

Can you reprogramme the top speed of the Sunstar? (On my Bafang kit it's as easy as pressing two buttons together to get into the programming.)

Dan - (hi there) - I don't want to hijack this thread with my own interests which are off topic, as I have a Sherpa and not a Rohloff (sob).  Perhaps a separate thread?  This is an exciting time in the e-bike world - lots of innovation (bit like mirror-less cameras - which is my other big passion) and may become of interest to Thorn owners as we get older.

"Transmission" seems a good place. Dan, I've been waiting till you returned to civilization to ask you to move the entire thread out of the "Rohloff" section before some lurker too hurried to read the whole thread rushes out to buy a motor that may or may not fit his Rohloff-equipped Thorn. Once it has been moved, I'll edit the posts to remove confusion.
« Last Edit: June 21, 2015, 03:01:10 PM by Andre Jute »

Danneaux

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Re: Installing an electric mid-motor
« Reply #16 on: June 21, 2015, 03:40:52 PM »
Quote
Dan - (hi there) - I don't want to hijack this thread with my own interests which are off topic, as I have a Sherpa and not a Rohloff (sob).  Perhaps a separate thread?
Will do soonest possible, fellows.

All the best,

Dan.

ians

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Re: Installing an electric mid-motor
« Reply #17 on: June 23, 2015, 02:31:14 PM »
Andre

I've decided to go with Bafang.  Just need to choose the right kit now - 250V or 350V. 

Thanks so much for your time and help.

ian

Andre Jute

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Re: Installing an electric mid-motor
« Reply #18 on: June 23, 2015, 04:42:17 PM »
Thanks for moving the thread, Dan.

Ian, what was the key consideration that made you decide on the Bafang BBS over the Sunstar? (Next to the price, of course.)

ians

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Re: Installing an electric mid-motor
« Reply #19 on: June 23, 2015, 08:54:56 PM »
(ditto Dan).

A number of things, Andre, including your take on it (not insignificant).

The Sunstar may be better (?) - but at twice the price, I can't imagine it twice as good. 

I also realise this is a fast moving field.  When I bought my first Thorn, I saw it as an investment - a bike for life. I never imagined changing it.  But stuff happens and plans change.  I also saw the Sunstar in that light to begin with - but that's just plain daft.  There is so much innovation going on and a lot of it seems to attach itself to the Bafang.  All over the world people in sheds are tweaking this thing.

So the ability to customise the Bafang was a major consideration.  For a start - I like the ability to be able to choose/change the chainwheel myself - either through a third party specially-made chainring (like the Lekkie - love the blue) or through an adaptor (110BCD for example).

It looks easier to fit (myself) than the Sunstar.

I also thought very carefully what I wanted it for.  Or rather, not for.  I don't want speed.  I'll be happy at 15mph. I'm not going off road or climbing the Alps.  And if I could manage a 30-40 mile ride I'd be more than satisfied.

I guess overall, it was the realisation that these kits are more like consumables rather than investments. My needs will no doubt change again in the next few years and so flexibility becomes more important than long term performance.

I've decided on the 350V motor and will probably go for the 15AH battery (I want a bottle cage design).

Thanks again for your help.

Ian

Andre Jute

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Re: Installing an electric mid-motor
« Reply #20 on: June 23, 2015, 10:30:42 PM »
I guess overall, it was the realisation that these kits are more like consumables rather than investments. My needs will no doubt change again in the next few years and so flexibility becomes more important than long term performance.

[NODS EMPHATICALLY] This is the key to understanding of the function and application of these electric motors.

I was not at all surprised or disappointed when after several years my Bafang QSWXK clocked out. Over its life it cost about Euro 0.16 per kilometer; 16 cents a klick elicits the response "so what?"  Especially when the alternative is stopping cycling altogether because I live among hills, zero flat roads except the lethal main drag. I was perfectly happy to buy another Bafang.

***

I should be very interested to hear which batteries are advised for you by the dealer, as my current battery is the one I used with the 250W QSWXK and it is either old (it must be approaching or perhaps already past its recharge limiting count of about 700 uses) or wrongly scaled for the 350W motor, because the rate at which it delivers its current isn't quite up to the last, steepest, section of several steep hills I ride almost daily.

ians

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Re: Installing an electric mid-motor
« Reply #21 on: June 24, 2015, 12:38:11 PM »
Andre

Woosh cycles recommend a 36V 15AH battery.  http://www.wooshbikes.co.uk/?batteries  Scroll down about halfway.

They've been very helpful both on the phone and by email (kits@wooshcycles.co.uk).

No stock until next month though ....

ian


Danneaux

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Re: Installing an electric mid-motor
« Reply #22 on: August 13, 2015, 10:44:01 PM »
A small side note, posted here as well as any, I suppose...

Talented trials and trick rider Martyn Ashton (of "Road Bike Party" fame and many other remarkable videos), broke his back and has remaqined paralyzed from the waist down After. He has completed his basic rehabilitation and is now back on a bike again.

His initial efforts were limited to coasting downhill on a full-suspension MTB, sitting in a bucket seat and dis/mounting with the aid of friends. Now, he is able to go solo, thanks to a mid-mounted electric motor, regaining much if his former mobility and already planning to make some new videos of his trick riding.  See:
https://video.fsnc1-1.fna.fbcdn.net/hvideo-xft1/v/t43.1792-2/11729744_894123124001872_451867652_n.mp4?efg=eyJybHIiOjE1MDAsInJsYSI6MTAyNH0%3D&rl=1500&vabr=706&oh=a31fc05087c95803e2c0d7f679d59cfc&oe=55CD3894

He must surely be driving on a throttle, as a true demand-type pedalec circuitry would be unsuitable to his needs.

Very nice to see Martyn back on a bike again, and a shining example of how motorizing a bicycle can make the experience possible when health issues might dictate otherwise.

Best,

Dan.

macspud

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Re: Installing an electric mid-motor
« Reply #23 on: August 14, 2015, 04:10:40 AM »
Dan,
Unfortunately that link isn't working for me, do you have another.
« Last Edit: August 14, 2015, 07:03:18 AM by macspud »

Danneaux

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« Last Edit: August 14, 2015, 05:22:50 AM by Danneaux »

macspud

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Re: Installing an electric mid-motor
« Reply #25 on: August 14, 2015, 07:17:00 AM »
Thanks Dan,
Great to see him back on a bike. I'm sure it will make a positive difference to his mental outlook getting back on two wheels and feeling the joy of the balance and movement.
When my father had lost his legs after having them amputated because of diabetic complications, getting back on a motorcycle give him such a mental boost.
Cheers,
Iain.
« Last Edit: August 14, 2015, 01:25:05 PM by macspud »

Andre Jute

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Re: Installing an electric mid-motor
« Reply #26 on: August 14, 2015, 11:33:04 AM »
I imagine he's driving on the throttle, as you say, Dan. The alternative controls, the so-called pedelec, depend on the cyclists somehow turning pedals. In the case of the mid-motor a couple of us have fitted, the pedelec controller is built into the motor case, getting its signal from inside the "bottom bracket" that is part of the motor, and would be slightly difficult to adapt as a DIY job (special tools, soldering skills, electronic knowledge). However, selfstanding pedelec control boxes, or those built into the battery bottle instead, are widely available and are sent their signal by a ring of magnets attached inside the chainring around the bottom bracket axle. They work on precisely the same principle as the slightly more refined pedelec signals built into the Bafang mid-motor.



Which leads us to this: A machine that's common in therapy rooms, and very likely known to him, looks like a table-mounted set of pedals. You pedal it by hand against electromagnetic friction. There would be no problem operating a pedelec control box from such a set of hand pedals, as also found on bikes for paraplegics.

Long story short: an integrated mid-motor might need dedicated tools and skills to make it usable, but a front or rear motor added to a standard paraplegic bike setup only needs some light fittings tiewrapped to standard parts around the transmission, no big deal.

Also, I think it very possible that, given his aerobatic skills, he would prefer the motor in the rear wheel if only to protect it better than it could be hanging low under the bottom bracket, but possibly for dumbbell balance as well (the speed with which you can break the bike from a steady state motion into a skilled manoeuvre), with the heavy battery in the central triangle for optimum weight distribution.

Exciting possibilities!
« Last Edit: August 14, 2015, 11:36:06 AM by Andre Jute »

jdeleener

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Re: Installing an electric mid-motor
« Reply #27 on: December 16, 2015, 02:00:02 PM »
Hello Andre,

I'm new to this forum, but found this topic since I want to build a new bike for commuting.
I was thinking of a combination of Rohloff hub and Bafang BBS02 mid drive kit.
Since you seem to have a similar combination: could you share your experiences? My local bike shop advised me against it. He said that shifting under load will be difficult. Even if I would stop to pedal for an instance, the BBS controller has some delay before the load is small enough to switch gear.
According to him, the commercial available ebikes with rohloff hub (with Bosh mid drives), have controllers which switch automatically the motor off when you switch gear, which should lead to a much smoother experience.

So I'm curious what your experience it :)

Cheers,
jan

Andre Jute

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Re: Installing an electric mid-motor
« Reply #28 on: December 16, 2015, 08:02:44 PM »
Hello Andre,

I'm new to this forum, but found this topic since I want to build a new bike for commuting.
I was thinking of a combination of Rohloff hub and Bafang BBS02 mid drive kit.
Since you seem to have a similar combination: could you share your experiences? My local bike shop advised me against it. He said that shifting under load will be difficult. Even if I would stop to pedal for an instance, the BBS controller has some delay before the load is small enough to switch gear.
According to him, the commercial available ebikes with rohloff hub (with Bosh mid drives), have controllers which switch automatically the motor off when you switch gear, which should lead to a much smoother experience.

So I'm curious what your experience it :)

Unless you're riding on hills, Jan, you don't need a Rohloff. See http://thorncyclesforum.co.uk/index.php?topic=7833.0

If you need or want a Rohloff and a midmounted motor (which is the best choice on all sorts of theoretical parameters), basically you can't choose a Thorn bike with a Rohloff because those adjust chain tension with an eccentric bottom bracket. My bike with the BBS motor is not a Thorn; another member with a BBS fitted it to derailleur Thorn, with a normal derailleur chain tension arm.

Your dealer is correct, a Bosch ebike with the Rolloff will be a smoother experience, and if you're merely buying/building a commuter for not overly demanding duty, it would be smart to go with the Bosch because it is likely to be the cheapest and least bothersome option. The good reasons for doing it the way we have is that you're already an expert bike builder, that you have a suitable frame already, that you intend to put the bike to heavier duty (speed, touring, load, really fat balloon tyres, rough roads) than the Bosch is designed for, and perhaps a few other reasons particular to individual cyclists; just to be different is not a good reason, and you won't save a huge amount of money.

If you're still determined to go ahead, my experience is that you can easily build a superior bike to the Bosch for any purpose but sheeplike commuting. It'll take a little more skill to ride, but it will be much more rewarding. My bike, compared to a Bosch, is the difference between a Bentley Continental with the biggest engine and a VW Beetle with the smallest engine they sell; my key interest is security of roadholding and handling at elevated speeds on very rough roads. See http://thorncyclesforum.co.uk/index.php?topic=3798

To deal with the dealer's specific complaint about the Bafang BBS midmotors overrunning when you let the throttle go or stop pedaling while the pedelec facility is switched in, it's a genuine complaint on the first day or two that you have the motor fitted, and then you hardly notice it. That is because the Bafang mid motor has such good torque that you only use a few gears of the Rohloff in most circumstance and you easily "ride through" by giving more throttle or switching up a level of assistance (explained in a moment), so that the need for a gearchange is less. It's perhaps not scientific riding, but I was never a roadie, and so couldn't care less; power-riding does me fine. Also, I find that if I want to change gears upwards, I just do it with a very slight or no lift, and if I want to change gears downwards, there is usually enough momentum to lift off the throttle for enough time to do it. The Rohloff's rotary, sequential gear control is a big help, because you don't have to change one gear at a time, you can change as many as the rotation of your wrist allows, so that I often change five or six gears at once, brrrt. Sure, you can get caught out near the top of a very steep hill, but that is a sign that either your gears or your battery are badly matched to your motor; you wouldn't even have got that far that fast without the motor.

These midmotors have torque coming out of their ears; even the 250W has a better torque spread in use than the highly illegal BPM front motors of fond memory, the previous champions. There is a throttle which, if you buy your motor from the right dealer, is set to give maximum assistance at all levels and speed (i.e. you can go as fast as your gears and battery will permit and you wish to set the speed for in the settings of the controller -- note what it says about buying from the right dealer, because some limp wimps and self-declared community policemen sell crippled motors at whose electronic settings you can't get to undo their selfrighteous stupidity). There is also pedelec assistance, which depends on how fast you pedal and what gear you're in -- and again, if you buy from the right dealer, is set or can be set to the max your motor and battery combination is capable of.

This pedelec assistance is 9 levels, or you can set the switch to skip two at a time or three at a time to give you a more convenient 5 or three levels.  I put the switches for all this right under my thumb and use it like the paddles under the wheel of my last Porsche to adjust my speed on the road, much more than I use the Rohloff gears. (In fact, I'm considering buying a battery so big that my Rohloff will be permanently in gear 11, the most efficient, direct gear, except for the very steepest hills, and except when used as an overdrive gearbox on some pieces of flat after a shallow hill where the motor will allow me to pedal up to full speed just at the top.) Below you can see the switch cluster peeking out from under my thumb at the bottom left of the photo. The reason you can't see the throttle is that my thumb is on it.


I have the 9 settings reduced to 5, of which no 3 is already far, far more powerful than my previous QSWXK front motor, itself no slouch, and four and five are like overdrives on a very powerful car, best saved for the open road. In town, on errands, I either have pedelec assistance switched off, and just use the throttle to break the bike loose, after that pedalling manually, or I use assistance level 1, which is plenty to let even a cardiac patient keep up with automobile traffic.

It could be said that the capabilities of the Bafang's built-in controller (again, if you buy from a dealer who sells a version that lets you get at the settings), used in the way I use them as a faux-tiptronic gearbox, makes the Rohloff an expensive indulgence. Of course, I could just be wearing the gears inside the Bafang midmotor faster; my QSWXK possibly (I haven't opened it yet) failed by melting the nylon gears.

There is no doubt in my mind that the Rohloff is sturdy enough to handle all the smaller Bafang motors (nominally 250 and 350W); I have no experience of the larger motors (500 and 750W).

I don't mean to be offensive, but just to ensure that we're on the same song sheet here, all of this is with hefty pedalling input from me; my bike is a key component in my exercise program so I use the motor to add a few watts when my heart is in danger of exceeding the permitted rate; in short, I control the motor's input by my heart rate as reported by my iPhone in the drybag on the photograph above (iPhone not in bag when photograph was taken because it was taking the photo, capice?). One could theoretically turn a pedal bike into an electric motorbike with one of the bigger Bafang motors and a big enough battery, but if that is what you want, it would be smarter and cheaper to buy an electric scooter.

***

I didn't actually look at the Bosch -- I was looking at a class of bike a few steps up and wouldn't ever consider a bike with frame dedicated to particular motor -- but my understanding is that it is the best middle-of-the-road readymade ebike out there, perfectly satisfactory to the majority of commuters. Building your own isn't difficult if you can read plain instructions and have ever swapped a bottom bracket, but in DIY there is always the risk of stuff not working, and you having no recourse to exchange or warranty, and consequent waste of money.

Finally, you should consider Ian's point, that an electric motor setup is not a permanent capital asset but a consumable that you will write off totally in x number of years. I was happy when my QSWXK clocked out after three years; it cost me 16.5 eurocents per kilometer, which is exceedingly reasonable, so I bought another Bafang.
« Last Edit: August 25, 2019, 03:57:45 PM by Andre Jute »

Andre Jute

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Re: Installing an electric mid-motor
« Reply #29 on: December 17, 2015, 10:36:46 PM »
Still answering Jan's question:

Above I've said that a Rohloff is a pricey luxury if you're buying a torquey electric motor and don't skimp on the battery (it must have a continuous current rating to match the needs of the motor or it will cut out on hills). What you really need is a superstrong widely spaced 2- or 3-speed gearbox. But there isn't one.

The choice of hub gearboxes you can use with an electric midmotor is limited. With the smaller, less torque-rich motors, you might get away with a Shimano or equivalent eight- or eleven-speed box. You'd have to be careful how you change gear and accelerate, especially from a standstill, and rely on the throttle more than on the pedelec, or you will rip it apart.

Remember, 15 or 18W from the motor -- or more in the bigger motors -- is multiplied by the gearbox through its gear ratios, just over 3 times in the Shimano 8-speed boxes, well over 5 times in the stronger Rohloff box.

With the Bafang BBS midmotors, even the 250W base model, some of us think the minimum hub gearbox is the CVT NuVinci which, being gearless, is fundamentally more capable than the geared hub boxes of the Shimano class. It is likely that the NuVinci would be suitable up to about 350W of Bafang BBS power with relatively spirited use. By 500W you might have to be more careful with your inputs from throttle and pedelec.

Effectively, that leaves the Rohloff, a superstrong gearbox with a superfluity of gears for this purpose.

The Rohloff is essential for the 750W version of the BBS motor even if you will basically use only gears 10 and 11 and perhaps the overdrive gears 12, 13 and 14, and highly desirable for using the 350 and 500W motors at all exuberantly.

With the lower torque of the 250W BBS mid motor, the abundance of Rohloff gears come back into their own because they fill in where the motor's torque runs out, and the top 7 gears will probably see common use, perhaps lower in really hilly country.

In effect then, we have started at a topclass gearbox as an expensive luxury which needs to be justified, and arrived where it is a choice of either the Rolloff gearbox or no gearbox because there is really only one other sensible choice (the NuVinci) and even that would limit your riding style.

All those Rohloff gears are usable torque multipliers because they are so strong. So a Rohloff makes a 250W motor, which in the BBS midmotor range is pretty torquey anyway, a very palatable option, and the 350W motor with the Rohloff is frankly so awesomely powerful that I don't see why people should want the bigger 500 and 750W motors except that they're not cyclists but motorcyclists.

So, a limited number of very specific cases of Bafang BBS installations suit the NuVinci, but for the least strenuous of those possibilities (a flatland commuter or utility bike, anyone?) its automatic shifting option and its price makes the NuVinci an attractive option. Every BBS installation suits the Rohloff while several of the more strenuous require it, without any alternative (except to use no physical gearbox but apply the motor's own software as a virtual gearbox).

There you have it. If you can afford a Rohloff and want it, you should fit it and be prepared for jeers from the traditionalists because you've spent so much money to use only a handful of its 14 gears.