Rohloff Speed 14 hub gearbox with Bafang BBS mid-motor: installation and use

chain

Pedelecer
Jul 14, 2011
56
4
Hey Andre ...what happened with this build ?
I'd love more info as i want to do a similar rohloff build and need info re alternate chainrings/chainline etc . PLEEEEEZ update!
thanks
bill in exeter
HEADLINE SUMMARY: The Utopia Kranich, a big, fast, very stiff crossframe design running on 60mm Big Apples at the very low pressure of 2 bar, and the Bafang BBS01 36V/350W turned out to be an inspired combination of bicycle and motor. At first you might think the Rohloff hub gearbox I used in this build (see http://www.pedelecs.co.uk/forum/threads/bafang-8fun-bbs01-installation-eclips-ebikes-gives-service-over-and-above.20718/)isn't necessary, because the Bafang motor's software gives you 9 "speeds" anyway, that a Shimano 8-sp might do as well, but I have experience of Shimano hub gearboxes that last 5000km or 3000m, so it would be a false economy. If you cheap out on the gearbox, you'd better stick to the 250W motor, and my guess is that even then you will have to ride carefully to protect the gearbox. For anything bigger than the base 250W Bafang motor, the Rohloff is very likely essential.

IN USE: Such a pleasure, I don't know why I didn't fit a Bafang BBS the day they came out. My bike carries my plein air painting gear permanently in the pannier basket and handlebar bag; I'm no weigh weenie. All up the bike, me, and the usual gear and water (in a stainless steel Nathan bottle that weights a pound by itself) weighs upwards of an eighth of ton. I live in the beautiful but hilly countryside of West Cork (I'm a writer, so I can live wherever I want, but here is pleasant); from my house there is no direction I can go on cycling-safe roads that don't involve constant steep hills. I found my previous motor, a Bafang QSWXK, already a motor known for its good torque, wasn't always happy with the demands put on it, and it burned out in about three years, which I thought good value as it was in constant use. With experience of the Bafang BBS-01 in 36V/350W form, I'm slowly forming the opinion that, unless the rider is an idiot boy racer or really very heavy, the 250W Bafang will probably have enough oomph for most applications. Note that I am more interested in making it to the top of every hill than in top speed as I basically use my bike for exercise, that is as a pedal bike with electric assistance on the steepest hills (see for instance Bombing down the hill at Kilbrogan).
HOWEVER, everything is not roses at the very beginning of your relationship with the motor and its controls; you have to learn to use everything smoothly. A complete installation of all the bits that come in the box Eclips Ebikes www.eclipsebikes.com gives you a whole lot of software for convenient operation of the bike. This is just the headlines: you will have both a throttle and a 9-stage or -speed pedelec programme, which you can easily cut down to a five-stage pedelec programme if you're too lazy to press a button or don't care about being in the most efficient speed range or for some reason want an ultra-fast change. The pedelec operation has pseudo-torque control nowhere near as sensitive as on the Bosch-Panasonic bikes, and starting off in pedelec mode, which on switchon defaults to speed 1, max torque (!), will soon rip the aliminium sprocket, cheap chain and ali chainring of a Shimano Nexus installation out of order, and in the long run I can easily see it damaging the Nexus and Alfine gearbox internals too. Even with a Rohloff gearbox, I automatically switch the pedelec setting to zero as I get on the bike, and take off with the throttle, switching the pedelec settings back in at the bottom of the steep hill behind my house. This is all very conveniently done with a three-button switch you can mount wherever you like: I mounted mine under my left thumb on the same side of the bike as the thumb throttle, and both in a position such that I am certain to let go of the throttle when I apply the brake. You learn soon enough not to jerk your chain and gearbox with any of the BBS controls, and to integrate the pedals, throttle and pedelec controls, to minimize both jerking and run-on in traffic. Run-on is when the pedelec oomph exceeds your input by so much that the bike continues to roll forward quite powerfully under its own momentum even after you stop pedaling. In this sense, on the five-speed setup, the top two speeds ae superfluous in rush-hour style traffic... After nearly three years experience with the QSXWK, itself a powerful motor, I learned very quickly to adapt to the BBS, but I can see that complete newcomers to electric motors may want to practice a bit on a totally clear supermarket parking lot before they go out in traffic and perhaps embarrass or hurt themselves.

SPECIFICATION CAUTION: Make sure you get a battery that's up to the motor, or you'll soon be spending more money. I had the good, strong 8Ah battery left over from my QSWXK front-motor installation, and found it a convenient format on my particular bike, so I kept it. Thing is, while everyone makes a song and dance about how far the battery will carry you at full speed or half speed or whatever, that's really irrelevant. In everyday use, what limits the operation of any electric motor in its most critical operation (pulling you over the last, steepest bit of the hill after you run out of puff) is the rate (usually called C by the techies) at which the battery can deliver current, and this is, to cut a long story short, for practical purposes a function of the pure size of the battery: mo' Amp-hours are better Amp-hours! An analogy to grab hold of is the pressure in a pipe connected to the bottom of a tank: the bigger the tank (given that it is full), the greater the head of pressure.

IS THE ROHLOFF TOTAL OVERKILL? Maybe the CVT NuVinci stepless gearbox, especially in its automatic (torque-sensing, self-protecting) automatic version, will last. Maybe a Shimano Alfine will survive the base Bafang BBS 250W if the owner is vigilant against putting too much torque into the box, especially at start off. I have little faith in these possibilities; I had a full-auto Di2 Nexus 8sp box and wrecked it in less than 3000m (see Andre's Trek Navigator L700 "Smover), and this was a faull auto Di2 made for European commuting and sporting bikes, not the wretched cut-down semi-manual Di2 Shimano sells to Dura-Ace roadies. Frankly, I think that even the smallest Bafang midmotor has enough torque to require the industrial/agricultural strength and German precision of the Rohloff. The alternative in my mind is not another hub gearbox but a single speed bike with the midmotor software used as a pseudo-gearbox.

*** The rest of my post was lost by the stupid board software and I don't have time to write it all out again. I've answered your specific question about chainlines at http://www.pedelecs.co.uk/forum/threads/rohloff-speed-14-hub-gearbox-with-bafang-bbs-mid-motor.22386/
 
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BAH48

Pedelecer
Nov 6, 2012
166
15
Appleby Cumbria
My BBS02 750 works perfectly with my Shimano 8 speed hub and I don't think that the hub gear is unduly stressed. There is no pseudo torque sensor, just a rotation sensor that works very well. With my Bosch bike I always have to put in a certain amount of effort, with the Bafang I can pedal hard if I want to, but if I'm feeling tired I can decrease the effort and still have maximum assistance. Both bikes are good, but quite different.
 
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chain

Pedelecer
Jul 14, 2011
56
4
My BBS02 750 works perfectly with my Shimano 8 speed hub and I don't think that the hub gear is unduly stressed. There is no pseudo torque sensor, just a rotation sensor that works very well. With my Bosch bike I always have to put in a certain amount of effort, with the Bafang I can pedal hard if I want to, but if I'm feeling tired I can decrease the effort and still have maximum assistance. Both bikes are good, but quite different.
I have a couple of low-mileage worn-out Shimano boxes, so I had to decide between proper German engineering that lasts forever (and comes with what is effectively a lifetime guarantee) and buying five or six Shimano and being left with nothing. It was a no-brainer, helped along at that time by moving into a house my wife liked on the steepest hill in a town called the "Rome of Ireland". Perhaps you're happy to put so much power through a Shimano box that I wrecked with nothing more than my legs to power it, because you have a gentler touch. We'll see in a few years whether your optimism is justified. I hope you're right, because a Rohloff is outrageously expensive.

Actually, Bafang at first tried to pretend that the rotation counter was a torque sensor of some magical kind. The point I'm making by "pseudo" is that only the Bosch item (and a not-very-common aftermarket item available from China) is atrue torque sensor, and none of the pretenders, including Bafang's, whatever they call it now, is real.

Your Bosch is a Big Brother Machine, BAK48. It doesn't work for you, it works for the German government. It measures carefully how much torque you provide by leg power, and adds precisely the same, not an iota more, because the German mindset is that whatever isn't permitted is streng verboten. By contrast, the Chinese probably have an Italian consultant who noticed how loosely the EU wrote the most recent peddle total power spec (basically it is what the manufacturer says it is, which is a good reason to buy Bafang, because they make very modest power claims!), and very likely decided they could also try it on with the ratio between user power-input and what the motor provides. I'm not going to complain! Are you?
 
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BAH48

Pedelecer
Nov 6, 2012
166
15
Appleby Cumbria
Well, I do treat my bafang motor gently as you correctly surmise. It doesn't feel as robust as the Bosch motor. The point about the rotation sensor is that it is just a switch, nothing sophisticated, either on or off. With my system, once a particular speed has been reached, depending on the power level and gear, I can put in as much effort as I like. If I pedal hard, I can take some or all the load off the motor or I can ease off to virtually zero input and have full power. Obviously, this not like a bicycle, it's a moped. The Bosch system rides like a real bike and conforms to the regs.
 

flecc

Member
Oct 25, 2006
52,763
30,349
The point I'm making by "pseudo" is that only the Bosch item (and a not-very-common aftermarket item available from China) is atrue torque sensor, and none of the pretenders, including Bafang's, whatever they call it now, is real.
Not so, Panasonic units have a true torque sensor and that first appeared a decade before Bosch even thought of making a pedelec motor unit.
.
 

chain

Pedelecer
Jul 14, 2011
56
4
Not so, Panasonic units have a true torque sensor and that first appeared a decade before Bosch even thought of making a pedelec motor unit.
.
Thanks, Flecc. Actually, earlier on, back up the thread or in the material that the stupid programmer lost, I said "Bosch-Panasonic".
 
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