rear hub, internal gear options.

[Retrorockit]

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.

[ncmired]

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

[markitos144]

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?

[Retrorockit]

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.

[Defjr333]

I have used both Shimano(186%) and Sturmey(178%) 3spd IGHs. Between those would go with the Shimano. Better price/ slightly larger gear range. BUT, I switched to a Sturmey 8 spd (325%)IGH that gear 1 is the 100%, not the middle gear. I find I never used the "granny gear" and prefer the extra gear range at the "top end". It helped increase my top end speed by about 20%.

[calfee20]

You should put together a little review of that IGH because they are not very common. What size sprockets did you end up with?

[Defjr333]

I switched to a 18T sprocket. Front Chainring still 48T. I would do a review, but my test bike would be too different to others to be of any technical info use. I run my BBSHD thru a Phaserunner at 80v and 45A. So, im a little odd. Wonderful IGH though. I never used the granny gear on the 3spd models, the 8spd is perfect. Start off in 1st and only shift as speed increases demand.

[Retrorockit]

I'd love to hear how a 45A. 80V. bike runs. Shimano has a 5 speed 1:1 low IGH for E bikes. But not in the US market so far.
https://bike.shimano.com/en-EU/produ...-C7000-5D.html

[calfee20]

I'd love to hear how a 45A. 80V. bike runs. Shimano has a 5 speed 1:1 low IGH for E bikes. But not in the US market so far.
https://bike.shimano.com/en-EU/produ...-C7000-5D.html

Exactly.....

[Defjr333]

My BBSHD wired to a Phaserunner controller with dual 21s4p packs in parallel. Phaserunner can handle up to 100v 100a, the BBSHD, however is at its breaking point at 80v 50a. I WOULD NOT ATTEMPT THIS ON AN MTB. Too much jarring. My street only ride it does well on. I will try to post some resent videos of it on my build page. Sorry I dont get to spend much time on this site, I have a new project, plus work:(