Design for high powered freewheel sprocket for e-bikes

Hello fellow e-bikers, & gear heads, & need advice please on a new type a freewheel sprocket design I'm making for mid drive ebikes, at least I've never seen it done. The idea is to make the left side driven wheel freewheel while not powered by motor, this also eliminates spinning chains and magnet drag, making it easier to peddle. One thing that's makes this project special is their is no thread on freewheels that strip the threads, but instead a short key shaft mounted freewheel that can take serious power.

A summary of how it goes together is a 2 1/2" bolt on adapter disk installs on the disk brake side. A key shaft 1.25" outer diameter keyway collar welded on to the disk. For a 3/8 (10mm) axle the shaft itself needs to be 1.25" OD with a 5/8 bore hole to slide over axle. A keyway freewheel that accommodates a sprocket & that is (high quality power rated), slides on shaft. The dropout needs space from the spinning shaft, so I guess a thin 1/2 inch tube goes in side of the shaft bore to back up on the hub & keep dropout clear.

I'd like to hear others opinions on the idea, & regenerative braking vs freewheeling for affecting better milage. If the parts can be found or machined, what key shaft freewheel can take up to 21,000 watts(28hp) for my project? What chain & sprocket should I go with, #35, or #219 go kart chain? I can get it all to fit with some slight widening of the dropouts with longer axle. My problem is I have a 9/16 (14mm) axle & larger sizing of components.

Plan to use with a mid drive QS 205 V3, 5 turn hub motor as a mid drive. My battery is 7kwh, 103.6v 68ah. Instead of having a top speed of 60+mph, I'll gear it for 42mph max for more torque. A lightweight mag wheel seems to take torque better than spokes. Need ideas & hope to get 300 close to 300 miles range on a charge.

Here is the adapter to bolt on the disk brake side. A thin sleeve goes around axle to give dropout space frome spinning shaft. What freewheel would be best to use, & how much power can it take?

Ok. New info tells me a standard freewheel will not be able to take the torque, but instead some sprag clutch freewheel with less jarring effect from power. Is there a roller clutch that has a mount for sprocket teeth, or do I need to weld on a sprocket to it?

orange streak said:

Ok. New info tells me a standard freewheel will not be able to take the torque, but instead some sprag clutch freewheel with less jarring effect from power. Is there a roller clutch that has a mount for sprocket teeth, or do I need to weld on a sprocket to it?

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What info are you talking about? You have it backward. Sprague clutches are far less durable than I high end freewheel. Many of us have been down this road.

Also, I think you are answering a question that no one is asking with this project. Many of us are already running left side drive with a freewheeling system. In my case, the left side freewheel is on the jackshaft of the drive unit. The chain is always spinning when the wheel is spinning. But this has a minuscule affect on coasting efficiency. As long as the motor is nor being driven while coasting, the coasting efficiency is great.

I use WB HD FW from sickbikeparts. It's been holding up to a beating with 6kw (100a/200a phase) geared @ 30mph. I run it on the right side of a threaded hub and then adapt it to my freehub body for cassette pedal power. The only downside to using threading for attachment imo is it can be rather difficult to un-thread, if you ever want to. No worry though, the threaded driver is likely the last thing that would fail. I do prefer to not have the chain spinning when not under power.

I saw a hint of blue on your jackshaft recumpence, is that a WB FW as well?

recumpence said:

What info are you talking about? You have it backward. Sprague clutches are far less durable than I high end freewheel. Many of us have been down this road.

Many of us are already running left side drive with a freewheeling system. In my case, the left side freewheel is on the jackshaft of the drive unit. The chain is always spinning when the wheel is spinning. But this has a minuscule affect on coasting efficiency. As long as the motor is nor being driven while coasting, the coasting efficiency is great.

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A highly regarded ES member said I should go with sprag clutch freewheel becuase they are more durable & are not jolting on start ups which abuse the pawls in a standard freewheel? Its mainly my project to have just the rear wheel turn freely. What can I use that will stand up to 28hp?

orange streak said:

recumpence said:

What info are you talking about? You have it backward. Sprague clutches are far less durable than I high end freewheel. Many of us have been down this road.

Many of us are already running left side drive with a freewheeling system. In my case, the left side freewheel is on the jackshaft of the drive unit. The chain is always spinning when the wheel is spinning. But this has a minuscule affect on coasting efficiency. As long as the motor is nor being driven while coasting, the coasting efficiency is great.

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A highly regarded ES member said I should go with sprag clutch freewheel becuase they are more durable & are not jolting on start ups which abuse the pawls in a standard freewheel? Its mainly my project to have just the rear wheel turn freely. What can I use that will stand up to 28hp?

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I have run 40 hp through a white industries freewheel without a problem. I run them exclusively.

Highly regarded....lol, (thanks)

I could/should have been more clear, putting a freewheel on the driven end of the reduction introduces quite a bit of "play" in the drive set up... if you put the freewheel on the driving sprocket you will reduce the hammering on the pawls. & this is where a sprag would be a viable application. I have exploded freehubs & freewheels

I doubt you have room for a "properly sized sprag clutch" in the rear wheel....even on your cargo bike.

Matt's set up is about as good a design as your going to get with bicycle components. The long run of freewheeling chain is problematic...but workable.

recumpence said:

I have run 40 hp through a white industries freewheel without a problem. I run them exclusively.

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40hp, now that's serious! Are you running this power through the freewheel with a keyway mount? Surley what I see on there website, thread on freewheels will not hold up & the threads will strip out at only 3hp+.

Thud said:

Highly regarded....lol, (thanks)
I have exploded freehubs & freewheels

I doubt you have room for a "properly sized sprag clutch" in the rear wheel....even on your cargo bike.

Matt's set up is about as good a design as your going to get with bicycle components. The long run of freewheeling chain is problematic...but workable.

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Doing my best to stuff it in the dropout to all fit. Probably right about fitting a sprag clutch. A standard freewheel seems compact, & the rest can be milled down to fit better.

While I'm at it, I to need to fix the chain tensioner issues, so whats better? I'm after a smooth running chain. Considering a roller skate wheel, but I don't want chain to fall off any more and should it have a spring tensioner? My other small stiff tensioner on my kit just may bend.

orange streak said:

Thud said:

Highly regarded....lol, (thanks)
I have exploded freehubs & freewheels

I doubt you have room for a "properly sized sprag clutch" in the rear wheel....even on your cargo bike.

Matt's set up is about as good a design as your going to get with bicycle components. The long run of freewheeling chain is problematic...but workable.

Click to expand...

Doing my best to stuff it in the dropout to all fit. Probably right about fitting a sprag clutch. A standard freewheel seems compact, & the rest can be milled down to fit better.

While I'm at it, I to need to fix the chain tensioner issues, so whats better? I'm after a smooth running chain. Considering a roller skate wheel, but I don't want chain to fall off any more and should it have a spring tensioner? My other small stiff tensioner on my kit just may bend.

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Don't worry about the threads. They will not strip.

Well I'm very, very, skeptical on trusting the threads to hold at those power levels at all, that's pretty much why I came up with a key shaft design. As much as these white industries freewheels cost, I would be p***** off, if it broke on me. I'd also like to consider a high quality freewheel for cross county touring, with a fast charger. Well, I'd love to hear some more opinions, & I don't think company will care about such a customer under such application to work, & will say no go. But I'd like to share more pics of my bike for now.

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Well, you can spend a huge amount of time building something if you would like, but, I can tell you with absolute certainty that the threads are the least of your concerns.

Ok, I'll accept the freewheel method & is compact, unless other are against it. & #35 chain should do the trick for the power, & longevity. I kept stretching my 1/8 bmx chain with low power. This bikes purpose is to be also efficient for touring.

orange streak said:

Ok, I'll accept the freewheel method & is compact, unless other are against it. & #35 chain should do the trick for the power, & longevity. I kept stretching my 1/8 bmx chain with low power. This bikes purpose is to be also efficient for touring.

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Wow, not sure what you are doing, but, I use BMX chain exclusively with CRAZY HUGE power without stretching (and I always have).

I prefer the extra heavy duty BMX freestyle or trials chains for my high power builds. But, one of my 28,000 watt bikes is running a cheap department store BMX chain for 600 miles without any signs of stretch.

I am with recumpence on this one also,
BMX chain is tough...& the 418 heavy duty (still bicycle) chain is tougher yet if you have any concerns.

#35 is great if you need finer gearing choices, is less expensive than "premium" grade bicycle products, but you will be fabbing more "special" parts to implement. you don't want any cheap bicycle components on a cross country machine.

lets clarify your goals if we can: your looking for a nice, freewheeling left side drive. Max coasting ability.

is there more?
question: what is your biggest gripe with the HPC set up on the yuba?

Thud said:

I am with recumpence on this one also,
BMX chain is tough...& the 418 heavy duty (still bicycle) chain is tougher yet if you have any concerns.

lets clarify your goals if we can: your looking for a nice, freewheeling left side drive. Max coasting ability.

is there more?
question: what is your biggest gripe with the HPC set up on the yuba?

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I personally built this bike up with its components,
Its not a HPC model. Sonny Yalung sold me the mid drive kit. But the kit came with a jack shaft to run through the freewheel, & I did not like the way it ran with 7 speeds & the chain alignment was not good, & I even stripped a 7 speed freewheel & runned the wheel!, so I changed the drive line to the right side to be reliable. I've stretched my weak chain several times & have bent the motor bicycle chain tensioner like 7 times no matter how its adjusted, so I'm ditching the tensioner & starting over. The kit has a small tensioner arm on that side I'm going to try out, & hope to use something reliable like a roller skate wheel with high quality bearings, instead of the cheap plastic cog that is loud & annoying. The bike is a tank, but I want it to be as reliable as a motorcycle really. If at all possible braking is a issue, & I've explored options, & I love my front mag wheel & hope to upgrade the fork & wish to install a largish motorcycle brake. I have several accessories but I'm playing with efficiency to improve my milage. Currently 21wh/mile at 20mph. Working on aerodynamics. My one & only build so far. This sure is off topic from the title, but I need the advice & improvements.
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recumpence said:

Well, you can spend a huge amount of time building something if you would like, but, I can tell you with absolute certainty that the threads are the least of your concerns.

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+1

That smaller diameter shaft with keyway would fail way before the threaded freewheel would fail. I would expect the paw's in the freewheel would deform or sheet before the threads were impacted.

The freewheels are strong, you're unlikely to break it with torque. Most #35 chain is cheap garbage, people use #219 because kart racing has driven some robust chains to get made in that size. I realize human legs have a lot of torque and a ton of people do fine with bicycle chain. Personally I break around 2-3 chains a year on my pedal-only road bike just riding, and wouldn't feel too confident increasing the torque loading above human leg torque levels.

liveforphysics said:

+1

That smaller diameter shaft with keyway would fail way before the threaded freewheel would fail. I would expect the paw's in the freewheel would deform or sheet before the threads were impacted.

The freewheels are strong, you're unlikely to break it with torque. Most #35 chain is cheap garbage, people use #219 because kart racing has driven some robust chains to get made in that size.

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No one can doubt Luke, not even I. So, I guess I'll just start by buying a bolt on freewheel adapter from station inc., & a white industries freewheel, & adapt a larger sprocket on the freewheel for the heavy duty bike chain. #219 may just be over kill then. Glad to get that figured out.

I have one last questions though that I'm not to good at figuring out yet.

If the final idea for the bike is to use a QS 205 V3_hub motor & my voltage can get it up to 60+mph on 26" wheels. Then what size of sprocket, what gear ratio do I need to get a max speed of 40mph?? which should give me a little more torque.

Did I mention that im planning on buying a yuyang 36fet controller rated for 10,000 watts continues (overkill!). A friend flipped his bike at almost 50mph!, got to be carefully with this one, but he had 32s lipo battery.

liveforphysics said:

recumpence said:

Well, you can spend a huge amount of time building something if you would like, but, I can tell you with absolute certainty that the threads are the least of your concerns.

Click to expand...

+1

That smaller diameter shaft with keyway would fail way before the threaded freewheel would fail. I would expect the paw's in the freewheel would deform or sheet before the threads were impacted.

The freewheels are strong, you're unlikely to break it with torque. Most #35 chain is cheap garbage, people use #219 because kart racing has driven some robust chains to get made in that size. I realize human legs have a lot of torque and a ton of people do fine with bicycle chain. Personally I break around 2-3 chains a year on my pedal-only road bike just riding, and wouldn't feel too confident increasing the torque loading above human leg torque levels.

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Is that Derailleur chain or BMX chain? I've never broken a BMX chain in my life. I can press 700 pounds with my legs at the gym and I've never broken a BMX chain. Neither have I ever broken one on one of my high tower builds. However, Derailleur chain is wimpy as anything. I've broken several of them myself as well. BMX chain is awesome however and I would never have a problem using it. You can get the extra heavy-duty BMX chain and it'll last the life of the bike.

I'm using 1/8 bmx chain, but I'll be sure to pic of the heavy duty type this time around. Any body know how to reduce a 1:1 ratio 60mph to 40mph gear ratio?

Has anybody on endlesssphere ever made a sturdy bike fork with a motorcycle brake setup, I'm going that route hopefully, but I think that more weight has to be on the front, but I don't want more weight, just a motorcycle caliper tab welded on the fork, & large motorcycle rotor to fit on bicycle hub & repainted to match the paint. Want to do this becuase its a heavy bike!, current using only a 180mm tektro rotor, & im not using front rim brake anymore.

I still have those questions left, but thank you for the info you've provided so far.

orange streak said:

I kept stretching my 1/8 bmx chain with low power.

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Chains don't actually stretch; they get longer from wear on each pin and bushing. The main factor in chain elongation is using sprockets that are already worn out, or don't have enough teeth for the job. I'm guessing you kept putting new chains on trashed sprockets and killing them. But nothing starts that cycle of destruction faster than using a too-small sprocket in either position.

13t is about the minimum sprocket size for reliable power transmission and reasonable chain wear rate. 16t is much better, but 21t and up is best in terms of efficiency and chain wear.

Then a nice sprocket, 13 teeth + chain guide will need to be fitted on my small chain tensioner arm. Its thick aluminum, so I hope not to bend it.
I'm buying the high quality thread on freewheel, & go to test it out.