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  • The Trail Pot Launches: A National Mountain Biking Development Fund
  • mravilious
    Free Member

    dazzydw: The big improvement in durability with our powertrain comes mainly from the gearbox.
    Gearboxes are inherently more durable than derailleur gearing systems.

    Take the gearbox in a car for example: generally speaking it requires no maintenance and is still going strong after hundreds of thousands of miles when other parts of the car reach end of life.  This is because gearboxes use hardened steel gears, lubricated with oil, and protected from the elements.

    Contrast this with derailleur gearing: pressed steel sprockets (not high strength hardened steel) which easily damaged and are exposed to water, dirt, road salt etc.

    We have tested the gears within our gearbox on a high power dynomometer we built, which is capable of loading the gears with the worst case peak load they will ever see in the real world, continuously.  In this way we were able to complete the equivalent of 10 years of real world heavy duty use within a few weeks. We then continued the testing, and the gears eventually failed in the way we had expected, based on simulation models we had previously run using specialist gear design software. Your question has made me realise we should really publish the results of the testing!

    Also it’s worth mentioning that we’re not the first to develop gearboxes for bicycles, Pinion GmbH and Effigear (France) have been manufacturing gearbox drivetrains for bikes for 10+ years, and these products are well proven to be durable.  In June this year, Pinion launched a combined motor and gearbox for the e-bike market, which has been very well received. PINION MOTOR.GEARBOX.UNIT | Motor and gearbox in one unit

    Our combined motor and gearbox is directly comparable to Pinion’s system: equally compact, similar motor power, similar weight.  Bombadier group (Canadian manufacturer of trains, jet aircraft and many other things) heavily invested in Pinion, so clearly they are convinced that gearbox powertrains are the future for e-bikes!

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    mravilious
    Free Member

    Torque of mid drive motors (Shimano, Bosch, Brose, Mahle etc) is defined at the output sprocket, which is after the reduction gearing within the drive unit.  It could be defined at the input (eg at the motor shaft, before reduction gearing), but this isn’t the industry standard.

    The torque our motor produces before the reduction gearing is about 3Nm (peak), but obviously this is a meaningless number if comparing to the torque at the peak output sprocket of the Shimano EP8  (85Nm).

    Power is simply Torque x rpm. so you can define power or torque at any point within a powertrain.

    Torque is quite a confusing metric for most people, and as I say we’d need to specify 8 different torque values (one for each speed) so we decided to instead express the output as power in Watts.

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    mravilious
    Free Member

    Hi this is Mark from Intra Drive Ltd.Thanks for your interest!
    The weight is 4.5kg without cranks – this is displayed on our website.
    The torque, which is normally specified at the output sprocket on mid drive motors, is hard to define, because we have an 8 speed gearbox….  so it changes depending which gear is selected.  I can give you some numbers, but they won’t be directly comparable to Shimano Bosh etc.  Hence we do not publish this data (and neither do Pinion).

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