Would this idea work for regen braking with a mid-drive?

[WhiteSkyMage]

Hey guys,

I just wanna ask - I know this might have been asked before, but I would like to know if this could work...

Usually the eBike kits come with a front freering, for stationary pedals while the motor turns the drive train (correct?). How about I don't actually use a rear free-wheel and let the whole drivetrain spin together with the wheel? I guess at that would mean that I would hurt the inertia of the bike, but if I have a controller that accepts reverse current, then wouldn't that be effectively a working regen braking system for a mid-drive? I know motorcycles don't usually have a back freewheel, so that's why I'm asking.

Is there a way to do this? Can I use a rear "fixed" hub (not a freehub) or rather to "lock up" the freehub so it's not free and have my drivetrain turn 100% of the time while the bike moves? Keep in mind - I still want to be using a rear derailer for changing gears while the whole drivetrain is moving (but not engaged by the pedals or motor).

Disclaimer - I do not care about drivetrain wear and frequent replacements (if you are going to warn me about that). Please assume that have a room full of drive-train components.

 

[E-HP]

You can do this, the tradeoff being you can't coast. If you switch to a Phaserunner, or other controller that supports electronic freewheeling, then you can coast, as long as you have battery. If your battery runs out, then good luck pushing it.

It takes a little while to get good enough with the throttle to do what you're proposing, but not too long. If you have cruise control, you can use that for "coasting" or at least give your throttle hand a break.

 

[WhiteSkyMage]

You can do this, the tradeoff being you can't coast. If you switch to a Phaserunner, or other controller that supports electronic freewheeling, then you can coast, as long as you have battery. If your battery runs out, then good luck pushing it.

It takes a little while to get good enough with the throttle to do what you're proposing, but not too long. If you have cruise control, you can use that for "coasting" or at least give your throttle hand a break.

Why would I not "coast" when I will have my front chainring using a freewheel? I.e. I won't be pedaling, the motor won't be engaged, but the drivetrain will still be turning because the bike is moving....
This would generate current in the motor and recharge my battery.

However - I wonder, what will happen if I switch gears? Will that be a problem?

 

[Blacklite]

This would generate current in the motor and recharge my battery.

Where do you think the energy to generate current in the motor and recharge the battery comes from?

 

[qwerkus]

Hey guys,

I just wanna ask - I know this might have been asked before, but I would like to know if this could work...

Usually the eBike kits come with a front freering, for stationary pedals while the motor turns the drive train (correct?). How about I don't actually use a rear free-wheel and let the whole drivetrain spin together with the wheel? I guess at that would mean that I would hurt the inertia of the bike, but if I have a controller that accepts reverse current, then wouldn't that be effectively a working regen braking system for a mid-drive? I know motorcycles don't usually have a back freewheel, so that's why I'm asking.

Is there a way to do this? Can I use a rear "fixed" hub (not a freehub) or rather to "lock up" the freehub so it's not free and have my drivetrain turn 100% of the time while the bike moves? Keep in mind - I still want to be using a rear derailer for changing gears while the whole drivetrain is moving (but not engaged by the pedals or motor).

Disclaimer - I do not care about drivetrain wear and frequent replacements (if you are going to warn me about that). Please assume that have a room full of drive-train components.

Problem is that there are no mid drives out there without an integrated freewheel. This means that they only work in one direction, and you can't regen. Even if you extensively mod one to allow for regen, you'll end up having to move your feet always at the cadence of the rear wheel, because the lack of freewheel will have rear wheel and pedals in sync - might not be as fun as it sounds ! And finally, you'd need a very strong chain: braking power is usually a magnitude stronger than pedaling power, so you'd easily snap a 3/32" chain.
If you want to regen with a mid drive, there is no way around a left drive system or at least a second axle between the crank and the rear wheel but that's usually overcomplicating things. Check out lightningrod's threads.
My two cents: get a bike with small wheels (24" max) and a dd hub. Less hassle, higher reliability ... and regen !

 

[amberwolf]

Why would I not "coast" when I will have my front chainring using a freewheel? I.e. I won't be pedaling, the motor won't be engaged, but the drivetrain will still be turning because the bike is moving....
This would generate current in the motor and recharge my battery.

If you are taking power out of the drivetrain to recharge your battery, you are braking, not coasting.

You can't coast *and* regen at the same time.

To coast you must freewheel, either mechanically or electrically, which means no load on the drivetrain. Any load (mechanical or otherwise) takes away forward momentum, which slows you down and eventually stops you.

If the drivetrain is just spinning the motor (and hte motor is not powered but is also not generating anything) then you can coast, but you aren't generating anything to recharge a battery with. If the motor has a gearing system (planetary, etc) from it to the chainrings (most middrives with physically small motors do, to convert the high-rpm motor output to crank-speeds), then it will add drag to the system even if you aren't tapping the motor for power.

However - I wonder, what will happen if I switch gears? Will that be a problem?

If you have a shiftable drivetrain in the rear (or front), with a derailer, and there is no freewheel in the rear, the chain is now being pushed across the top instead of being pulled, and may jump off the teeth along the top run (where it isn't tensioned except by the front pulling it, which won't be happening when the motor isn't powered and you're not pedalling) and jam up in your chainrings or cranks/etc.

The only reliable way I know of to make a non-freewheeling chainline work is to make it a single-speed with as straight a line from front chainring to rear sprocket as possible, with sufficient tension to ensure it can't jump off the teeth even under bumpy conditions, but not so much tension it stresses the chain or rings or bearings of front/rear.

That means you get no gearshifting at all, unless you use an IGH in the rear wheel (internally geared hub), and those will have built-in freewheels at the input. You could disassemble the IGH and defeat those, but it may require redesigning and machining some parts in there.

 

[amberwolf]

Usually the eBike kits come with a front freering, for stationary pedals while the motor turns the drive train (correct?). How about I don't actually use a rear free-wheel and let the whole drivetrain spin together with the wheel? I guess at that would mean that I would hurt the inertia of the bike, but if I have a controller that accepts reverse current, then wouldn't that be effectively a working regen braking system for a mid-drive? I know motorcycles don't usually have a back freewheel, so that's why I'm asking.

Motorcycles also don't generally have the chain right at your feet, or they are covered so you can't easily catch your clothing or appendages in them. You'll probably want to do that on yours as well.


Additionally, if you have the chain always spinning while you move, then unless you have freewheeling cranks the cranks will always turn as well, which means your feet will be forced around with the pedals all the time the bike is moving at all.

If you have freewheeling cranks, then the motor system used must not drive the cranks themselves, or regen can't work because the motor won't be able to be backdriven by the chain.

The Bafang BBSxx and other systems like them have internal freewheels as well (which you could probably defeat, but would likely have to machine parts to replace them with).

You'd need a system that uses a motor outside the BB that drives a chainring paired with the output chainring (that actually has the drivetrain chain on it to the rear). There could then be a freewheel between this paired chainring set and the cranks, to prevent backdriving your cranks and pedals.

I think the Cyclone systems are like this, but you'd have to check that they dont' have internal freewheels (which are usually there so you aren't backdriving the motor when just pedalling and no power, which can make pedalling pretty hard to do). If they have internal freewheels, you'd have to take them out and replace them with nonfreewheeling parts.

Is there a way to do this? Can I use a rear "fixed" hub (not a freehub) or rather to "lock up" the freehub so it's not free and have my drivetrain turn 100% of the time while the bike moves? Keep in mind - I still want to be using a rear derailer for changing gears while the whole drivetrain is moving (but not engaged by the pedals or motor).

See my other post about derailers and chainlines in "reverse" tension...they're not designed around that and will at best require you to tension the top of the chainline (which normally is done by pulling the chain forward by the pedals/chainrings) as well as the bottom (which the derailer does).

I can tell you from experience with early CrazyBike2 drive setups that it wont' reliably work to backdrive a standard unmodified shiftable-sprocket/chainring chainline. The chainrings in front and the pedals will "eat" the chain and break everything along the way. Which can also break your rear wheel and your frame if the tension on the chain gets high enough during the incident before the chain itself breaks. (yes, I did this too, from the same root cause though not during a non-freewheeling-drivetrain setup...but it would also happen in that case).


Another consideration is that shock loads thru the chain from hard braking with it (especialy if all you have is on/off regen, like most controllers do) can snap the chain itself (where the load from driving the chain wouldn't), so you would probably want to carry spare chains with you (or a chain tool and spare links).

 

[amberwolf]

Another discussion thread for this basic idea
https://endless-sphere.com/forums/viewtopic.php?f=28&t=46947

 

[WhiteSkyMage]

However - I wonder, what will happen if I switch gears? Will that be a problem?

If you have a shiftable drivetrain in the rear (or front), with a derailer, and there is no freewheel in the rear, the chain is now being pushed across the top instead of being pulled, and may jump off the teeth along the top run (where it isn't tensioned except by the front pulling it, which won't be happening when the motor isn't powered and you're not pedalling) and jam up in your chainrings or cranks/etc.

The only reliable way I know of to make a non-freewheeling chainline work is to make it a single-speed with as straight a line from front chainring to rear sprocket as possible, with sufficient tension to ensure it can't jump off the teeth even under bumpy conditions, but not so much tension it stresses the chain or rings or bearings of front/rear.

That means you get no gearshifting at all, unless you use an IGH in the rear wheel (internally geared hub), and those will have built-in freewheels at the input. You could disassemble the IGH and defeat those, but it may require redesigning and machining some parts in there.

Alright, I didn't take this into account. I thought that the rear sprockets will also be "pulling" the chain from beneath (the derailer) which will be enough to tension the chain from the front and that would somehow "work itself out".

So physics really isn't on my side on this one. And even if I have free-wheeling pedals, and an electrical freewheel with phaserunner, the gearing system are still gonna cause an issue the moment I decide to do regen braking, because the chainline will not be straight and that would cause me issue with the chain falling off. I was searching around the web for fixed rear hubs (instead of freehubs) and only found them on bikes with fixed gear. I wondered why....well, you just made it clear why that's the case, so thanks so much!

 

[WhiteSkyMage]

I can tell you from experience with early CrazyBike2 drive setups that it wont' reliably work to backdrive a standard unmodified shiftable-sprocket/chainring chainline. The chainrings in front and the pedals will "eat" the chain and break everything along the way. Which can also break your rear wheel and your frame if the tension on the chain gets high enough during the incident before the chain itself breaks. (yes, I did this too, from the same root cause though not during a non-freewheeling-drivetrain setup...but it would also happen in that case).

Another consideration is that shock loads thru the chain from hard braking with it (especialy if all you have is on/off regen, like most controllers do) can snap the chain itself (where the load from driving the chain wouldn't), so you would probably want to carry spare chains with you (or a chain tool and spare links).

I'd assume that if I had this experience at 50+km/h, it will be one hell of an incident that I will have to walk back home with a fully broken drivetrain and most probably an injury or two. The thing is I'll have to be carrying a spare drivetrain parts (chain, cassette and some other parts) in order to service it on the road. That's not unreliable if I have to count on those tools every time I go out on a journey.

Well guess I'll have to scrap it and just get a foldable photovoltaic panel, put it in the backpack and go. That would probably be much simpler way to recharge the battery "on the way".

 

[amberwolf]

Alright, I didn't take this into account. I thought that the rear sprockets will also be "pulling" the chain from beneath (the derailer) which will be enough to tension the chain from the front and that would somehow "work itself out".

I thought so too, when I started that version of the CrazyBike2 system...learned otherwise the hard way with mangled chain, sprockets, and other parts.

So physics really isn't on my side on this one. And even if I have free-wheeling pedals, and an electrical freewheel with phaserunner, the gearing system are still gonna cause an issue the moment I decide to do regen braking, because the chainline will not be straight and that would cause me issue with the chain falling off.

Yeah, that's the other major problem.

It is possible to design a system that can shift gears and keeps tension on both sides of the chain, and keeps a straight chainline...but you'd be designing and machining parts to replace existing bits inside various bike parts.

If you took two identical rear clusters at each end of a chain, and disabled (welded?) the freewheel clutches on them, and flipped the one in front 180 degrees, so it's narrow end was inboard, then made a derailer that would always pop the chain off the larger gear first, down to the next smaller one, just before it tried to shift the other end to the larger one, and there was only enough chain to ever wrap one set of sprockets this way, not extra chain like there is with a regular tensioning derailer, you could shift gears with a straight chainline at all other times than shifting. Because there's no "extra" chain, it should also keep tension easily enough (you could add a tensioner top and bottom if necessary, but it may have to release tension during shifting).

IIRC Naeem (numberonebikeslover) did something like this on one of his bikes a decade ago or so, but I don't remember how well it worked for him.

This is more or less how a belt variable transmission works in some systems, like in a drill press, and kind of how a conical-pulley belt cvt works, whcih are also systems you could use for shifting gears in such a system as you want to make...it's just a lot of custom work to get it all going together on a bicycle.

 

[amberwolf]

I'd assume that if I had this experience at 50+km/h, it will be one hell of an incident that I will have to walk back home with a fully broken drivetrain and most probably an injury or two. The thing is I'll have to be carrying a spare drivetrain parts (chain, cassette and some other parts) in order to service it on the road. That's not unreliable if I have to count on those tools every time I go out on a journey.

Well guess I'll have to scrap it and just get a foldable photovoltaic panel, put it in the backpack and go. That would probably be much simpler way to recharge the battery "on the way".

Yes, it would. :lol:

It's not that you *can't* do what you want to do...just that it's not an easy or simple task given the specific requirements you have (of being able to shift gears, *and* have regen thru that same system, especially).


If you could forego the gearshifting on the motor part, and only have that for pedalling, you could drive the *left* side of the rear wheel from the motor, and use no freewheel on that, and the motor would not run thru the pedal drivetrain at all. That would greatly simplify the entire system and at least double it's reliability (because you have two independent drivetrains only common from the rear wheel hub to the ground).


You could also make a Thud-style two-gear dog-shifter for the motor system, wthout any freewheels in it. There may also be existing few-gear transmissions you could use; they're just lossier than derailer-chain systems (about 2% per stage for those).

 

[WhiteSkyMage]

I'd assume that if I had this experience at 50+km/h, it will be one hell of an incident that I will have to walk back home with a fully broken drivetrain and most probably an injury or two. The thing is I'll have to be carrying a spare drivetrain parts (chain, cassette and some other parts) in order to service it on the road. That's not unreliable if I have to count on those tools every time I go out on a journey.

Well guess I'll have to scrap it and just get a foldable photovoltaic panel, put it in the backpack and go. That would probably be much simpler way to recharge the battery "on the way".

Yes, it would. :lol:

It's not that you *can't* do what you want to do...just that it's not an easy or simple task given the specific requirements you have (of being able to shift gears, *and* have regen thru that same system, especially).

Yeah - I don't think I'll go as far as doing too much custom work on a enduro ebike frame. I just want to build an ebike from the ground up. That's all.

If you could forego the gearshifting on the motor part, and only have that for pedalling, you could drive the *left* side of the rear wheel from the motor, and use no freewheel on that, and the motor would not run thru the pedal drivetrain at all. That would greatly simplify the entire system and at least double it's reliability (because you have two independent drivetrains only common from the rear wheel hub to the ground).

That idea feels like the best solution.. Even though a transmission system was often called an *advantage* of using a mid-drive motor. Because of this, and having PAS, I wanted to forgo a dual drivetrain (which I see on many custom enduro ebikes) and just go with 1 drivetrain. However, I am not sure how much power an 8-speed chain could endure (3000-6000W is quite a bit no?) so, wouldn't that be a reliability concern? Hence I am leaning towards this dual drive train which you suggested. Unless I'm wrong that is, and a Cyclone is be perfectly alright with a normal 1/2x3/32 drive train with transmission. I might need to choose between this feature and regen braking...

You could also make a Thud-style two-gear dog-shifter for the motor system, wthout any freewheels in it. There may also be existing few-gear transmissions you could use; they're just lossier than derailer-chain systems (about 2% per stage for those).

I am really unsure how this works. Might wanna give me a bit of examples of how this looks and works?

 

[amberwolf]

If you could forego the gearshifting on the motor part, and only have that for pedalling, you could drive the *left* side of the rear wheel from the motor, and use no freewheel on that, and the motor would not run thru the pedal drivetrain at all. That would greatly simplify the entire system and at least double it's reliability (because you have two independent drivetrains only common from the rear wheel hub to the ground).

That idea feels like the best solution.. Even though a transmission system was often called an *advantage* of using a mid-drive motor. Because of this, and having PAS, I wanted to forgo a dual drivetrain (which I see on many custom enduro ebikes) and just go with 1 drivetrain.

shiftable gear transmission is the biggest advantage, but another is that you have a normal, stronger, spoked wheel on the back, instead of a hubmotor with much shorter less "springy" spokes, which make for a weaker wheel. (partly length, partly angles, etc).

However, I am not sure how much power an 8-speed chain could endure (3000-6000W is quite a bit no?) so, wouldn't that be a reliability concern? Hence I am leaning towards this dual drive train which you suggested. Unless I'm wrong that is, and a Cyclone is be perfectly alright with a normal 1/2x3/32 drive train with transmission. I might need to choose between this feature and regen braking...

I don't know how long a human-power-designed drivetrain can handle power levels much beyond human power (call it a thousand watts for peaks; actual torque (which is what does things in) depends on the person and the gear chosen for the moment). You have chains, bearings, frame joints and tube designs, etc., all involved.

Many people have built high-power middrive systems, so you may find some info on this in other threads over the years, though the search here leaves a lot to be desired, so perusing thread titles in the non-hubmotor drive section is likely to be one of the simpler ways of finding some of them. :/

The Cyclone is one system that can be pretty high power; there's at least a few threads about the "3kw+" versions.

If you don't mind breaking stuff and wearing it out, as you said in the first post (assuming a roomfull of spares), you can run whatever power levels you like thru the drivetrain, as long as you are using it the same way your pedals use it.

It's systems that start using parts designed to do one job to do a different job, or in a different way, that you start to run into problems other than overly-quick-wear and the like.



FWIW, unless you're really doing motorcycle-level stuff, or serious cargo-hauling in adverse conditions, you generally don't need that much power thru a shiftable-gear bicycle drivetrain to do a particular job.

I think way back when I had CrazyBike2 powered by a powerchair brushed motor with gearbox, thru the cranks and pedal drivetrain, I was probably using 500-700w or so, and while it didn't go fast (partly because it wasn't geared to) it sure could pull hard (hard enough to fold up, break, bend, and tear apart the drivetrain and bend and break frame/wheel parts whenever things derailed from frame flex and the like). I ended up going hubmotor because I needed reliability more than I needed the torque and ability to change gears for the motor. Mine wasn't as well-designed as stuff you see for sale....


If you describe exactly what your bike has to do for you and under exactly what conditions it has to do that, we can better help you figure out how to do it without (as many) dead-ends as you may otherwise find, and possibly for less cost in money and time.

You could also make a Thud-style two-gear dog-shifter for the motor system, wthout any freewheels in it. There may also be existing few-gear transmissions you could use; they're just lossier than derailer-chain systems (about 2% per stage for those).

I am really unsure how this works. Might wanna give me a bit of examples of how this looks and works?

That's something you'll just have to look at Thud's thread(s) about his dog-clutch shifter 2-speed transmission. It's probably from about a decade ago, when people were looking for something reliable, small, lightweight, sturdy, and not that hard to make, for the various ebike races / competitions (which died out not long after then, so most of that development dried up, too).
https://endless-sphere.com/forums/viewtopic.php?f=28&t=14818
others
https://endless-sphere.com/forums/viewtopic.php?f=28&t=8644

 

[DtiK]

Hey guys,

I just wanna ask - I know this might have been asked before, but I would like to know if this could work...

Usually the eBike kits come with a front freering, for stationary pedals while the motor turns the drive train (correct?). How about I don't actually use a rear free-wheel and let the whole drivetrain spin together with the wheel? I guess at that would mean that I would hurt the inertia of the bike, but if I have a controller that accepts reverse current, then wouldn't that be effectively a working regen braking system for a mid-drive? I know motorcycles don't usually have a back freewheel, so that's why I'm asking.

Is there a way to do this? Can I use a rear "fixed" hub (not a freehub) or rather to "lock up" the freehub so it's not free and have my drivetrain turn 100% of the time while the bike moves? Keep in mind - I still want to be using a rear derailer for changing gears while the whole drivetrain is moving (but not engaged by the pedals or motor).

Disclaimer - I do not care about drivetrain wear and frequent replacements (if you are going to warn me about that). Please assume that have a room full of drive-train components.

A Problem is that there are no mid drives out there without an integrated freewheel. This means that they only work in one direction, and you can't regen. Even if you extensively mod one to allow for regen, you'll end up having to move your feet always at the cadence of the rear wheel,B because the lack of freewheel will have rear wheel and pedals in sync - might not be as fun as it sounds ! And finally, you'd need a very strong chain: braking power is usually a magnitude stronger than pedaling power, C so you'd easily snap a 3/32" chain.
D If you want to regen with a mid drive, there is no way around a left drive system or at least a second axle between the crank and the rear wheel but that's usually overcomplicating things. Check out lightningrod's threads.
My two cents: get a bike with small wheels (24" max) and a dd hub. Less hassle, higher reliability ... and regen !

i am writing this because i found this by searching cyclone discussions and paid attention to the mid motor regeneration.

I have had it in use for a year and it works well, no doubt about it. :thumb:


A: For example Cyclone 3kW has removable freewheel, and there is adapters available for non-freewheeling sprockets (staton-inc). The hardest part is to adapt rear wheel, or finding the right hub to rear wheel, without the freewheel.

adapter for cyclone: "20mm ID x .9" wide, 2 set screws, 6mm keyway, Freewheel Sprocket Adaptor"
non-freewheeling sprocket for that adapter: 15 Tooth 1/2" x 1/8" Sprocket Track Cog with 1.37 x 24 ID threads DICTA

and IGH -> needs jamming of freewheel or give up gears and go single speed hub. with a torquey motor, going to single speed is not a problem if the sprockets are sizes properly and the top speed is increased by weakening the field if bike needs to be fast (over 60km/h).

As I have narrow bike, installed Halo Fix-G Track Hub without freewheel (fat foot cog) to custom 26" rear wheel. (after the IGH hub finally failed the bearings.)


B: That is solved by putting freewheel between pedal bb axle and "sprocket package", and letting middle sprockets be on "other side" of that freewheel, in sync with rear sprockets and front (motor). The pedals only rotate when I use them on my feet. The sprockets rotate whenever the bike advances.

C: False. It works just fine. People run kilowatts of power through 3/32 and they don't snap. I have 4,3kW going towards and about 300W for braking/regen. No snapped chains. Well I use 1/8 chain but it's not significant difference.

It is usually a lateral throw in the line that breaks them, or a worn freewheel or a twisting sprocket that causes the chain line to change in traction, then the chain breaks... The two-row bearing freewheel is almost bound to be with the cyclone. (google sickbikeparts ultra heavy duty freewheel). This is what it needs to be rigid and longlasting.

D: False. I run mid drive regen just drive on regular right side setup, and no extra axles. I have as a controller phaserunner. Virtual freewheeling is a nice addition but not an absolute must. The bike can ride yes even when the power is off, "a little" heavier. Without virtual freewheeling, free roll is clearly worse but it rolls nonetheless. In the range has no effect but a maybe positively, as the power is either always used for advancement or braking (regenerative).


I wouldn't give up on that as it also replaces the rear brake, absolutely great system, and I would recommend to others if there is no need for gears. And the cyclone doesn't really need them, as long as you keeps the driveline strong and the sprockets as big as possible to avoid wear in heavy load. 8)

 

[qwerkus]

...

Interesting take, thanks for posting it. I also write from experience, and my 3/32" chain snapped like right away at around 800-1000w braking force. Maybe it was an alignment problem, like you suggested.
About the cyclone: do you use the version with a planetary gearbox or just the motor ? I never bother with the former, as they are way too loud for my taste.
And finally: do you have a picture of your BB + crankset ? I also though of uncoupling the human-pedal-freewheel from a fixed motor sprocket, but did not figure out a clean and solid way to do it. My knees won't do super wide q factors.

In the end, I calculated the weight of all the goodies I need for a proper mid drive regen setup, and find out it was more than a 6kg dd hub, so I went for the dd hub.

 

[DtiK]

...

Interesting take, thanks for posting it. I also write from experience, and my 3/32" chain snapped like right away at around 800-1000w braking force. Maybe it was an alignment problem, like you suggested.
About the cyclone: do you use the version with a planetary gearbox or just the motor ? I never bother with the former, as they are way too loud for my taste.
And finally: do you have a picture of your BB + crankset ? I also though of uncoupling the human-pedal-freewheel from a fixed motor sprocket, but did not figure out a clean and solid way to do it. My knees won't do super wide q factors.

In the end, I calculated the weight of all the goodies I need for a proper mid drive regen setup, and find out it was more than a 6kg dd hub, so I went for the dd hub.

I use version with planetary gears. And what comes as for the volume level, Phaserunner made it quiet enough for me. With stock controller it was shouting pretty loud.



My BB is basic "Square Tapered Bottom Bracket" from LunaCycle (regular cyclone part). Theres photo in LunaCycle website.

Can't remember what my cranks are but they are from BMX store, and it's regular square taper without fixed sprockets, but right one has same 1.37 x 24 tpi thread as freewheels usually -> makes it compatible with sickbikeparts freewheel.

 

[qwerkus]

My BB is basic "Square Tapered Bottom Bracket" from LunaCycle (regular cyclone part). Theres photo in LunaCycle website.

Can't remember what my cranks are but they are from BMX store, and it's regular square taper without fixed sprockets, but right one has same 1.37 x 24 tpi thread as freewheels usually -> makes it compatible with sickbikeparts freewheel.

Thanks a lot for the post. Maybe I'm just too stupid, but I'm not sure I get it: with that setup, depending on how you mounted the freewheel, either the motor or the braking will engage the ratchet of the fw and turn the pedals. You can't have both direction freewheeling ?

btw aweseom chain tensioner you built! I was wondering how you'd mad it withstand full braking force...

 

[DtiK]

My BB is basic "Square Tapered Bottom Bracket" from LunaCycle (regular cyclone part). Theres photo in LunaCycle website.

Can't remember what my cranks are but they are from BMX store, and it's regular square taper without fixed sprockets, but right one has same 1.37 x 24 tpi thread as freewheels usually -> makes it compatible with sickbikeparts freewheel.

Thanks a lot for the post. Maybe I'm just too stupid, but I'm not sure I get it: with that setup, depending on how you mounted the freewheel, either the motor or the braking will engage the ratchet of the fw and turn the pedals. You can't have both direction freewheeling ?

btw aweseom chain tensioner you built! I was wondering how you'd mad it withstand full braking force...

https://www.youtube.com/watch?v=B36gSMIcads
look at this but don't drop off your chair when you see it

With that setup it's possible to hold the pedals in place while driving and the driveline is moving, but on the other hand also drive normally through the pedals. At the end of the video I turn the pedals by hand from the other side.

you are right that a freewheel in both directions is impossible, as in a pedal relationship, it is true. If I REVERSE on the bike, the pedals will move along. But who reverses with bike? braking with chain is a different matter than a complete change of direction. Does not affect regen...

 

[DtiK]

And here is proof of the functioning of the regen. Look closely at the left edge of the screen. A positive watt-reading means the power taken from the battery, a negative one means the power supplied to the battery, in other words regenerative braking, the recovery of power to charge the battery.

https://www.youtube.com/shorts/rTAwt_Qq3lg

8)

 

[qwerkus]

you are right that a freewheel in both directions is impossible, as in a pedal relationship, it is true. If I REVERSE on the bike, the pedals will move along. But who reverses with bike? braking with chain is a different matter than a complete change of direction. Does not affect regen...

Got it! Thanks for the video. As long as the rear wheel and/or the motor rotate faster than the pedal, they won't move. If speed is negative (aka reverse) the fw clutch engages, and the cranks rotate. What changes when motor braking, is the chain tension: under normal power, upper chain half is under tension, while when braking, the lower chain half is working, correct ?

Man, I might even dig up that old project again, and set up a true mid drive regen. The only real problem left are gears: you basically drive single speed while I tried to implement a few pedal gears. Don't see how to setup that one without the second shaft / axle I mentioned earlier.

 

[DtiK]

you are right that a freewheel in both directions is impossible, as in a pedal relationship, it is true. If I REVERSE on the bike, the pedals will move along. But who reverses with bike? braking with chain is a different matter than a complete change of direction. Does not affect regen...

What changes when motor braking, is the chain tension: under normal power, upper chain half is under tension, while when braking, the lower chain half is working, correct ?

That's right, that's why it's now advisable to have a chain tensioner or guide that takes into account that the tight side becomes the loose side and the usually loose side of chain becomes the tight side. Simply: good to be tensioners on both sides, and springs long enough for the springs to stay in place but also not squeeze too much.

So I have such an arrangement, though I have not yet needed for a longer chain a tensioner on the upper side. Has worked quite perfectly with two tensioner rollers on primary chain.


https://ibb.co/WHRNJkC

 

[amberwolf]

Interesting take, thanks for posting it. I also write from experience, and my 3/32" chain snapped like right away at around 800-1000w braking force. Maybe it was an alignment problem, like you suggested.

It's also not the watts, themselves, is the torque applied (which will be different depending on wheelsize, gearing, weight of system, speed being braked from, time of application, how sudden an application of force, etc).