How often does the bbso1 need to be in the correct gear?

Discussion in 'Electric Bike Conversion Kits' started by flik9999, Jan 13, 2018.

  1. flik9999

    flik9999 Finding my (electric) wheels

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    Hello so I am soon going to install the bbso1 onto my bike. However as I have DT shifters I will often just stay in wrong gear and grind up the hill, is this style of riding likely to damage my motor. For example on a hill I might just stay in my 42x18 instead of shifting down to my 42x32.

    The motor comes with a 46t chainring so my gearing will be a bit on the high side. Just wondering if my style of riding is going to damage the motor as DT shifters can be annoying to shift with.
     
  2. flik9999

    flik9999 Finding my (electric) wheels

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    The motor says it can handle 80nm torque whatever that means.
     
  3. Benjahmin

    Benjahmin Pedelecer

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    I've never owned one of these so no expert. However any motor has a range of revs which it is happiest working within. As your motor is driving through your gear train, the gear you are in will affect its speed of rotation. If you are in too high a gear going up hill the motor will be spinning too slowly. This means that it will run inefficiently, a lot of the power consumed being turned into heat. Bad for the motor and battery range. In a worse case scenario the motor may stall or even burn out.
    I'm sure others will tell you what your cadence needs to be to keep the motor sweet.
    So, the answer to your question is ALWAYS.

    What are DT shifters anyway?

    p.s. The 80nM figure is meaningless as this changes every time you change gear.
     
  4. Fordulike

    Fordulike Pedelecer

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    On all the BBSxx units, it's best to be in a gear where you are pedalling at a high cadence when going up steep gradients. That's not to say that you have to be pedalling at the same speed as the gearing though. I ghost pedal quite often, where I'm turning the pedals at just enough cadence to kick the PAS in, but the motor is doing all the work.

    Bottom line, don't labour these units, something will give eventually!
     
  5. This is what I mean by a hub-motor being more relaxing. You need to be in the right gear all the time with a BBSxx. Torque goes up as the cadence goes down. That torque can damage the motor as well as the drive train. Running the motor too slow makes it run with very high current inefficiently, so it would soon overheat and blow the controller.
     
  6. Nealh

    Nealh Pedelecer

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    The controller will fry if continual use of too high a gear is used, the drive doesn't operate well when laboured so keep it spinning the faster the better.
    On my BBS01 I have a 42 blekkie and a 42 low gear.
    The first sign of a major issue on my one was a surge in power (excess amps) by the way of acceleration then at some stage an Error 12 on the lcd and then maybe an error 30. By then the damage is done and a new controller is needed.
     
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    #6 Nealh, Jan 13, 2018
    Last edited: Jan 13, 2018
  7. flik9999

    flik9999 Finding my (electric) wheels

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    DT:towntube shifters

    In regards to gearing im going up to 9 speed soon. Should i go for a close 12-16 or a wide 11-32?
     
  8. flik9999

    flik9999 Finding my (electric) wheels

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    Also mine came with a trottle is this strange flr bbxx?
     
  9. KirstinS

    KirstinS Pedelecer

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    No, perfectly normal. You don't have to use it

    throttles are legal on legal conversion kits
     
  10. willcee

    willcee Just Joined

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    OP mentioned 80N/M of torque being meaningless, where in hell do you get that engineering experience from.. that motor has that torque at its best speed, and its best speed is in the region of 80/90 rpm, this is why its likely been designed for 42 t chaindrive wheel, the rear gears multiply your torque at the pedals , like a car in 1st gear hill starting, you never climb hills in 3/4/5 from a standstill, so what the OP is asking originally , to try to get the motor, which pulling a low gear won't be in the torque curve, so he needs to use the frames down tube gear levers to assist by changing up the sprockets to an easier pushed gear.. I was reading on an American site about midmotors having internal fibre gear wheels disintegrating because they were being modded with a 52 ring and then from a stand still asking the motor to pull them away in top gear, highly likely they weren't experienced cyclists, just looking an easy way to save their effort & low cadence also, try taking your car from a standing start in 5th and smell the clutch, only car i know would do this is a Diesel PD 1.9 Golf which has maybe 160 lbs ft++ torque from a high tick over..just my 2p's worth .. will
     
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  11. anotherkiwi

    anotherkiwi Pedelecer

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    Which is also why they are best mated to an IGH for use on a commuter, you can change down when you please.
     
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  12. willcee

    willcee Just Joined

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    AGREED to a point, no internal hub gear will stand 80n/m torque for long, this being a held opinion amongst USA users, read that many are reverting to old 3 sp Sturmeys, of course these users may well be hopping the watts to max. Not hard to do away with the d/t shifters and place a pair of thumb shifters on the bars or use bar end shifters if its drop barred.. there are of course gear interrupter wires available to momentarily cut the motor enabling a clean shift, still pedalling of course.. will
     
  13. flik9999

    flik9999 Finding my (electric) wheels

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    Ok so my cassette is 11-32 gear. My gears are 11, 13, 15, 18, 21, 25, 28, 32. How low should i go down to at traffic lights on flat is starting in the 15 or 18 enough or should I shift all the way down to the 32.
     
  14. malkie0831

    malkie0831 Finding my (electric) wheels

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    On my BBS01 350W I usually start off in 2nd or 3rd (14-28 FW) saving the 28 for climbing hills. The lower you go the more battery power you will save, but the more frustrated you get changing gear all the time!
     
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  15. anotherkiwi

    anotherkiwi Pedelecer

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    I said "commuting" which is usually a little calmer than hooning around on a hot rodded BBS0x...

    1. In the US they have 500 and 750w motors. And many of the "little" ones are hot rodded via the software. Along with bad chainwheel choices they were probably seeing well beyond 80 nm. https://electricbike-blog.com/bbs02-chainrings/

    2. There were a lot of Alfine 11 speed hubs that were trashed, much less of an issue with the Inter 8

    3. Rohloff is rated by the factory for 110 nm
     
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  16. anotherkiwi

    anotherkiwi Pedelecer

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    Standard 46 tooth chainwheel? 21 or 25 depending on your assistance level. One of my party tricks is starting from a red light in third and assistance level 5, I find that in second it is too easy to wheelie...:rolleyes: Unrestricted that had lots of drivers scratching their heads as they tried to catch me.

    If you abuse your motor you will fry the controller , simples. :)
     
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  17. willcee

    willcee Just Joined

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    STRANGE how some guys talk about shifting down when i always called it shifting up because you are asking the chain to climb up to the bigger sprocket.. in answer to the OP question about starting off i would use a car analogy, unless you drive auto, i have both, so use your gears, that's what they are for, on a flat carriageway you wouldn't need the lowest effort sprocket 32.. i would say mid cassette in the twenties 21 say, and when you are up to speed change down the gears to 18/15 and be aware of your terrain rising or falling, the thing that's coming across in this discussion is ... the feeling that the OP isn't a long time served cyclist and unaware of what's needed on a pedal powered machine..you cannot cycle these like an automatic car.. maybe with a high powered hub motor 1000w yes.. but a mid motor no .. my opinion.. will
     
  18. The idea's right, but the explanation isn't quite right. Electric motors are different to IC motors. They make maximum torque at zero RPM where the back emf is zero. It's a bit complicated in that the controller limits current, so at low RPM the current doesn't change with RPM until it reaches some point, which might be something like 50% maximum RPM. Torque is proportional to current, so the torque would be fairly flat up to say 50% rpm, then it ramps down to zero at maximum RPM.

    Power is maximum at about 75% of maximum RPM because power = torque x RPM, and torque is flat until say 50% max rpm, then the ramping down is slower than the ramping up of the RPM - sort of.

    To summarise, it's very bad to run a crank motor too slow. It makes very high torque at that speed so it can damage things like internal gears, chain and derailleurs. Also, it runs inefficiently at that speed, which makes it overheat and wastes battery.
     
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  19. harrys

    harrys Finding my (electric) wheels

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    If you're were beating yourself up pedaling up that hill in a given gear without a motor, it's just as bad for the BBS01, Shift to a gear that lets you pedal faster and lets the motor spin better.
     
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