Affordable Production Model Geared Hub Motors over 1000-watts?

Go on any e-bike forum and you will find countless numbers of e-bike enthusiasts “over-volting” geared hub motors to massive wattages. However, in our world of delivering container loads of safe, reliable and consistently low warranty products, we just don’t have that luxury…

Most 5:1 reduction BPM’s are rated at 500-750 watts nominal and can be over-volted to peak at 1000 watts reliably. A few rare exceptions like the MAC and BMC motors can be over-volted much higher than 1000 watts (but usually below 1500 watts.) This is partly due to wider composite gears and more robust clutches. However, the manufacturers will say when being used as a mass production motor, 1000 watts is really the peak limit to operate safely without a lot of warranty phone calls. Also, these two motors cost more than double most other BPM’s.

We have tested a beveled corner, helical cut, metal planet gears with a matching helical cut ring gear but found that the motor noise just screams at anything over 500~750 watts. http://www.topsecretev.com/helical-cut-steel-planetary-gears-for-hub-motors/

Now, there is a patented nylon planet “spur gear” with matching profile reinforced steel scrim plates on each side. It’s a good idea to increase strength while reducing noise and is being sold in 1000-1200 watt geared hub motors.

We are also using double reduction, geared hub motors. Which nearly doubles the reduction to 9.6:1 and almost doubles the torque for any given input wattage under 1000 watts (over a traditional single reduction, spur gear BPM’s.) These have proven to be quiet and reliable with a much smaller footprint. However, the safe and reliable wattage is 750 watts nominal/ 1000 watts peak (for short periods of time only.) This motor operating at 750 watts would produce nearly 70Nm of torque, in a hub shell about 35-40% smaller than a traditional BPM.

Then there’s the next generation “large footprint” direct drive/ gearless hub motors. These are really moped or e-scooter motors in bicycle OLN frame widths. They can handle a lot of current but the torque output for the given wattage required is much lower than any geared BPM (when operating at under 1000 watts.) So these types of motors really only start to make sense when operating well above 1500watts. Given the added costs of the extra wide magnets, more copper, a larger 18~24 Fet controller and a substantially bigger battery required, it just doesn’t make that much sense in a street legal production model e-bike.

So until we can find a reliable, moderately priced geared hub motor that can operate between 1200~1500 watts safely and quietly for large scale production e-bikes, our search continues… Of course middle drive motors will provide the torque needed at lower voltages, but the off-the-shelf bicycle drive-trains are not really designed to match these large torque applications.

*Update 1/18/2018: MXUS has a few samples of a 1000 watt/ 100Nm geared hub motor but no update on the actual pricing yet.

*Update 9/18/2018: MXUS and Hengtai have 1000+ watt/ 100Nm geared hub motors in production and the cost is higher but still reasonable.

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8 Responses to “Affordable Production Model Geared Hub Motors over 1000-watts?”

  1. rafe husain January 9, 2017 at 6:46 am #

    interested in high rpm low weight geared motors

  2. topsecretev January 28, 2017 at 6:36 pm #

    High RPM is not a problem depending on your voltage. It’s the low RPM motors at high voltage that are more difficult to run efficiently.

  3. felix May 28, 2019 at 9:17 am #

    Hi, do you have more informations about the mxus / hengtai hi power geared hub motor ? Would be super interesting, especially with a locked clutch and regen.

  4. Felix Schalck May 29, 2019 at 4:02 pm #

    Well, thanks, but I know google too! I thought you’d have some test charts to show. Anyway – I contacted both companies, and asked for efficiency charts. The high power mxus geared hub is call GDR-19:https://www.alibaba.com/product-detail/2019-MXUS-48V-1000W-powerful-ebike_60835187546.html?spm=a2700.7724857.normalList.22.9d5b6d1f6QuUsJ
    From the efficiency chart they sent me, I’d say its performance is underwhelming. It seems like a super slow wound mac, which tops around 76-78%. I guess that’s why the motor has to be that heavy (5Kg) and large (140mm OLD): to suck up all that wasted heat.
    Still waiting for news from hengtai.

  5. topsecretev May 30, 2019 at 5:01 am #

    My bad, we are a consulting group not a community forum. I’ve only ever tried the 45kph MXUS at the factory but they have a few “new” iterations of the hub they are experimenting with (so I guess it depends on what spec’ed version of the hub you are using.)

    We have used the Hengtai extensively and it’s very nice hub. Very thin steel stator laminations (about half of Bafang’s standard lamination thickness for normal hub motors.) The shaped curvature magnets and reinforced gears are also an added bonus.

    Again, it comes down to spec of the motor: winding, laminations, magnet Gauss and shape etc… so don’t always believe the stock reports. Spec every part of the motor sample and do our stall-torque test yourself based on your sample motor.

  6. Felix Schalck May 30, 2019 at 8:32 am #

    I totally agree, but it’s very difficult to convince producer / seller to send you pictures of the internals. You’d have to buy a sample of each an test them yourself, for which most like myself lack time (and cash!). Now about your take an High Power Geared Hubs, I think the future lies in dual pinion geared like you mentioned. Those motors will always be more efficient, as their small inrunners can spin very fast and the high reduction still produce more torque. I only hope one company will come up with a dual helical gear set (chevron style) and no freewheel clutch to allow for regen – otherwise why bother with heavy hubs at all ? With no regen, mid drive win all the time over hubs when it comes to high torque and high efficiency.

  7. topsecretev June 12, 2019 at 11:14 pm #

    Hi Felix,

    We do test each and every motor by buying a sample before we decide to use in a customer’s production, it does get costly. Later this year we are testing a few mini “dual reduction gear helical cut” geared motors from AKM, Shengyi and Xiongda. It’s tiresome to spec and order all the motors but you need to test!

    For one customer, we do pin the clutch of a helical cut, dual reduction motor and we use coasting and braking re-gen. It get’s a little clunky when you let up of the throttle and reapply the throttle again at times. We’ve tried different controller programming and it’s still a little clunky when you reapply the throttle again. So we are switching back to larger BPM spur-cut gears for this model with coasting and braking re-gen.

    Cheers!

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