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  • toro1978
    commented on 's reply
    I think my confusion comes from the fact that I haven't been riding a bike derailers in years. So I completely forgot you need the cranks turning to in order shift. I assume that is why if one is used to deraillers and not IGH it might be initially weird to them having to disengage the motor and the "transmission" before a gear change.

  • Retrorockit
    replied
    PAS has the same one way clutch as the RPM sensing motors (except coaster brake versions). if you pedal slower than the motor, assist will stop completely due to no torque being applied to the pedals. If you use the throttle it will be the same result "ghost pedaling". With PAS if you pedal the same speed as the motor but apply no pressure (torque) you get no assist. This make it easier to modulate power when shifting . Many people like PAS mode because ghost pedaling doesn't exist. They feel theyr're doing "more" work because no work=no assist.. But if you use a low assist setting on non PAS motors, all extra power will be provided by you. So you can get to the same place a different way. With PAS to get full assist you must not only pedal fast enough but hard enough also. definitely more work.
    I own a BBSHD, and a PAS only TSDZ2.
    As far as wear goes a sprag or roller clutch is a highly evolved industrial product related to ball bearings. Failure is much more likely from overloading than wear. Standing on the cranks and pulling up on the bars might do it. You do see this on weaker IGH hubs not designed for mid drives. The Nexus 7 manual says don't stand on the cranks. A sprag will break, a roller clutch willl tend to slip. Either type can become jammed and not release.
    Last edited by Retrorockit; 08-26-2019, 11:37 PM.

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  • ncrkd
    commented on 's reply
    "It's called ghost pedaling. A form of make believe more or less" - forum phrase of the year, right there. Well written, Retro.

  • markitos144
    replied
    Thank you, that is very helpful feedback. Two quick follow ups:
    (1) Does slip between motor and pedal cranks, for example motor at 90 rpm and pedaling at less than 90 wear down the one way bearing sprag clutch? I would think that since many mid drives include a throttle, they expect frequent slipping operation.

    (2) The newer mid drive kits with no throttle, for example the Bafang M600 (MM G521.500C), have torque and cadence sensing. Am I right to assume that, if I gear the bike to hit 28 mph at 90-100 rpm, pedal at 75 rpm, and set to the highest assist setting, the mid drive will try to assist up to a higher rpm than my ghost pedaling? Asking the question a different way, what limits the rpm of these mid drives when they are set to max assist? Is it simply the equilibrium point between their output power and road load drag (aero/rolling/hill climb)... plus some maximum allowable RPM?

    Leave a comment:


  • Retrorockit
    commented on 's reply
    Using the throttle can work if you"re on 0 level assist. If you're on one of the higher assist levels as long as the pedals are turning at all the assist is there. There is also a 1/4 turn delay to resume power. The gear interrupt device blips the brake interrupt switch circuit each shift avoiding the need to stop pedalling completely, and wait 1/4 turn for power to return. PAS systems are better in this regard, but IDK of one with the power and strength of a Bafang mid drive.

  • Retrorockit
    replied
    If the motor is going 90 RPM and you're pedaling 75 RPM the one way clutch is letting the pedals go slower and you are actually doing no work. It's called ghost pedalling. A form of make believe more or less. You could produce the same result by using the throttle and not pedalling at all.
    if you want to actually be doing some work you either need to gear for the desired speed/cadence, or pedal as fast as the motor. Only if you stop pedalling completely will the motor cut out. There is also a 1/4 turn delay in the power coming back on to avoid the bike jumping on takeoff. This is also the reason for brake switches , to turn the motor off if the pedals are still turning.
    Last edited by Retrorockit; 08-26-2019, 07:43 AM.

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  • markitos144
    replied
    Thanks Retro for your feedback. Of course I've used sheldon brown gear calc. But I'm asking about something specific. From what I understand, there is a one way clutch (i.e. sprag clutch or similar) between the mid drive and the pedal cranks. So, the mid drive can be spinning at 90 RPM while I am pedaling at 75 RPM. I have never ridden a mid drive, so I am asking the folks on this forum if that is indeed the case. And if it is indeed the case, what does pedaling feel like when you are pedaling at a slower RPM than the mid drive is cranking the drivetrain/rear wheel? Will the "feel" of pedaling be incorrect? Will it feel like I am pedaling against no resistance... kind of like pedaling in 1st gear when you are biking down a hill where you should be in 5th gear? Or does it still feel like you get some resistance and each pedal revolution is applying a reasonable amount of torque into the system?

    Leave a comment:


  • toro1978
    replied
    Maybe not quite on topic, but I don't get why people are confused about letting go off the throttle (or stop pedaling) while shifting. When you ride a car (or a motorbike) you also let go off the gas pedal (automatic) or disengage the motor from the transmission (manul), right?

    Leave a comment:


  • ncrkd
    replied
    IF there was a industry motor mounting standard, I'd be a lot less hesitant of going that route - there isn't even a standard for the same vendor!

    Leave a comment:


  • Retrorockit
    replied
    There's a Bafang M600. but IDK anything about it. If you want to go 30mph and not spend time fixing anything except driveline expendables BBSHD is hard to beat. ( @ 1500W the entire driveline becomes expendable, but 750W etc. are options).

    Leave a comment:


  • ncrkd
    replied
    Originally posted by Retrorockit View Post
    I just saw a post at Endless sphere that the TSDZ2 can only handle 8-10A. continuos. 18A. is momentary and requires soldering a thermal sensor instead of a throttle, and open source firmware, and aftermarket display, to regulate output based on temperature. BBSHD =30A. continuos.
    Basically it's a 350W 20mph mptor.
    Thanks Retro for this update - kinda wondered after seeing the TSDZ2 motor "meat", as it were.

    Damn, I'm hoping the BBS02/BBSHD motors aren't the end of the line / as good as it gets.

    Leave a comment:


  • Retrorockit
    replied
    I just saw a post at Endless sphere that the TSDZ2 can only handle 8-10A. continuos. 18A. is momentary and requires soldering a thermal sensor instead of a throttle, and open source firmware, and aftermarket display, to regulate output based on temperature. BBSHD =30A. continuos.
    Basically it's a 350W 20mph mptor.

    Leave a comment:


  • Retrorockit
    replied
    Sheldon Browns gear calculator can let you try out as many gearing setups as you like. Several at once in fact. For gear units select the cadence you want. Put in the teeth of the belt sprockets as chainrings up to 3 sizes. then your 22T cog. Select the desired IGH and you will get a speed chart for that cadence with those gear ratios. You can add many other rear cogs also.
    https://www.sheldonbrown.com/gear-calc.html
    TSDZ2 has serious overheating issues. There is work being done on it here. But no final solution.
    https://endless-sphere.com/forums/vi...788&start=5500
    It's popular in the 350W European market. But lots of modding, repair, and upgrading needed.Very high maintenance.I would go with Bafang.
    If you can pedal at 90rpm which is not that hard on an ebike 60x22 gives 27.6mph.
    Shimano has a new 5 speed E bike rated IGH out in Japan and Europe. It's not in the gear calculator yet. 1:1 first gear.
    https://bike.shimano.com/en-EU/produ...-C7000-5D.html

    The only thing that costs more than doing it righ the first time, is doing it right the 2nd time.

    Leave a comment:


  • markitos144
    replied
    Hi Folks, I'm soliciting help choosing gearing for a 3-speed IGH...

    I'm planning to do a 500W continuous, 750+W peak mid drive conversion. Either the TSDZ2 or the just-being-released-with-steel-output-gear Bafang M600 (MM G521.500C) paired to a 14-series (52V) battery pack. 650b (27.5+) x 2.0" tires... likely Schwalbe Big Ben Plus.

    I would like help choosing my gear ratios. Alas, I've been spoiled by the 8-speed Shimano Alfine IGH and Gates belt drive on my 4-year old Faraday Porteur (Faraday rented space from my company, Mission Motors, when they were still a Kickstarter). Never needed a single bit of drivetrain maintenance in 4 years...

    So, I'm choosing between the 50T, 55T, or 60T Gates front sprocket and the smallest allowable 22T gates rear cog. My goal is to be able to cruise at 28 mph at a reasonable 75-80 RPM pedaling cadence. With the mid-drive's power, I don't think I'll need more than 3 gears, so I'd rather save the weight, cost and reliability risk and package the lightweight, cheap, robust Shimano Nexus 3. Top gear on the Nexus 3 is 1.36x.

    Which front Gates sprocket would you recommend between 50/55/60 teeth? I have done the calcs of human pedaling cadence with the aforementioned tire diameter as follows:
    75 RPM pedaling cadence
    50T:22T = 18.6 mph
    55T:22T = 20.4 mph
    60T:22T = 22.3 mph

    However, I know that the mid drive will be adding torque, so the rear wheel will be spinning faster than just a human pedaling cadence. I don't know how to factor that in. Or is it a bad idea to run the system faster than expected human pedaling cadence because the "feel" of pedaling will be incorrect?

    Thanks for feedback!

    Leave a comment:


  • Retrorockit
    commented on 's reply
    I have a Nexus 8, and a 50x 11-40 8 speed Rapid Rise derailer.I like them both .But with an 11-34 casette the S-A hybrid has the abilty to almost equal the gear range of the Rohloff.
    Last edited by Retrorockit; 08-24-2019, 06:49 AM.
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