What and where are free-wheel cranks found?
- Thread starter swbluto
- Start date
Miles said:
That helps tremendously, thanks. I still wonder how exactly everything interfaces with each other, but it sounds like you already have a good idea that it'd work, so I just order the parts and find out. :lol:
But... eh, yeah. Freewheels. They sell free-wheels with teeth? I know I saw one in LFP's broaching thread, but I had the idea that was a one-off. And, also, would adapting the ENO be as simple as replacing the bearing with, say, a shielded one? Also, doing this would isolate the pedals from the motor and the motor from the wheel?
Also, this "free-wheel" that is not an ENO that you speak of, is this something that can be easily researched and found or would it likely involve purchasing and finding out?
LOL! Sorry about that 
To clarify:
You can have regen., but, if you pedal without power, you will be back-driving the motor.
If you don't want to pedal without motor power (except in emergencies), this would be the simplest option.
To clarify:
You can have regen., but, if you pedal without power, you will be back-driving the motor.
If you don't want to pedal without motor power (except in emergencies), this would be the simplest option.
in order for the Autobikeâ„¢ to function the chain has to be in continuous motion.
so it comes with a freewheeling crank in the form of a sprague-clutch which is totally silent (if that's a concern).
if something cheapo like that can have a fwcrank it can't be all that difficult, can it?
so it comes with a freewheeling crank in the form of a sprague-clutch which is totally silent (if that's a concern).
if something cheapo like that can have a fwcrank it can't be all that difficult, can it?
Miles said:
In this scenario, you're imagining the motor would directly connect to the LH wheel sprocket? That'd take a pretty large sprocket to implement a gear ratio of 12:1, wouldn't it?
Also, where does one find a bi-drive rear hub? I assume that means that a freewheel can be fitted to left side and another one can be fitted to the right. If they can't be found, can they be pretty easy to make?
No, it's the best way to isolate the motor from the pedals with the system we were discussing. If you want this rather than regen.
EV Deals sell a Bi-Drive hub: http://www.evdeals.com/USPD%20Drive%20Parts.htm There are others.
I'm warming to this set-up.......
EV Deals sell a Bi-Drive hub: http://www.evdeals.com/USPD%20Drive%20Parts.htm There are others.
I'm warming to this set-up.......
Miles said:No, it's the best way to isolate the motor from the pedals with the system we were discussing. If you want this rather than regen.
EV Deals sell a Bi-Drive hub: http://www.evdeals.com/USPD%20Drive%20Parts.htm There are others.
I'm warming to this set-up.......
So I think you're referring to the one that says
So, I take it the USPD adapter enables a freewheeling sprocket on that side?
If that's so, that'd allow the motor to not turn while the wheel is turning. Would the LH crank on the pedals still have its own free-wheel to directly isolate the motor from the pedals (directly) as it uses the cranks as a "jack-shaft" for reduction using two chain-rings? And this is the "not-ENO but some special unknown one" freewheel?
No, you will need a left-hand freewheel for the left-hand side of the hub.. (Odyssey & ACS make them). You can fix your sprocket to this. This freewheel will isolate the motor from the pedal drive and will also avoid driving the motor when coasting.
The freewheel on the right-hand side of the hub will isolate the pedals from the motor.
Almost there
The freewheel on the right-hand side of the hub will isolate the pedals from the motor.
Almost there
Miles said:No, you will need a left-hand freewheel for the left-hand side of the hub.. (Odyssey & ACS make them). You can fix your sprocket to this. This freewheel will isolate the motor from the pedal drive and will also avoid driving the motor when coasting.
The freewheel on the right-hand side of the hub will isolate the pedals from the motor.
Almost there
Yeah, I think I get there's two free-wheels on the rear hub and there's a sprocket on the left hand side. How's the motor connecting to that sprocket?
Is it doing something like this...
View attachment 1
or this?
If it's the top one, what's happening at the cranks? Is it RH trial crank + freewheel + 2 chainrings?
Or is "nothing" happening there? Just two chain-rings used for a gear reduction that just happen to work perfectly for our purposes? (If it's this, I don't understand how the pedals are isolated from the motor since both would be using the LH crank)
Thanks. Now...
I need to hunt for a freewheel sprocket without pawls that happens to also serve as a sprocket. I take it that'd be a highly custom order from someone? :lol:
I think the RH trials crank + Chainring should be easily findable online. I'm guessing I'll also need a longer bottom bracket spindle and maybe another bottom bracket to fit it.
edit:
Wait, so something like this might work for the freewheel sprocket (And I'd just need to pull out the pawls)? http://www.staton-inc.com/Details.asp?ProductID=2349
Here's another one:
http://www.staton-inc.com/Details.asp?ProductID=2356
And... how could you tell it'd take the stress of the motor? I'd imagine an ENO on the LH wheel sprocket would be used since I'm guessing that's the freewheel that would see the majority of the stress (Highest torque loading).
I need to hunt for a freewheel sprocket without pawls that happens to also serve as a sprocket. I take it that'd be a highly custom order from someone? :lol:
I think the RH trials crank + Chainring should be easily findable online. I'm guessing I'll also need a longer bottom bracket spindle and maybe another bottom bracket to fit it.
edit:
Wait, so something like this might work for the freewheel sprocket (And I'd just need to pull out the pawls)? http://www.staton-inc.com/Details.asp?ProductID=2349
Here's another one:
http://www.staton-inc.com/Details.asp?ProductID=2356
And... how could you tell it'd take the stress of the motor? I'd imagine an ENO on the LH wheel sprocket would be used since I'm guessing that's the freewheel that would see the majority of the stress (Highest torque loading).
Actually, no, as long as you can open the freewheel to remove the pawls. Typically this isn't that difficult, as long as (unlike me) the parts you have aren't old enough to be rusted together internally. :lol:swbluto said:
The pawls that you see (darker metal tabs) in the pics of the opened freewheels earlier in the thread simply lift out of those slots sideways, along with a little spring. Once removed, any freewheel is now just a bearing.
If you don't care where it comes from and have a handy source for used BMX bikes, you can get them off of those easily enough, if you have the removal tool or the ability to make one. I made one by welding two bumps onto a wrench, grinding the bumps into squares that line up with the rectangular depressions on these common BMX freewheels. Then I just take the nut off the axle, stick the wrench on there, a large fender washer over that, and put the nut back on down to the washer but loosely. Hit the wrench with a mallet or hammer a few times counterclockwise while holding the wheel, and voila! One BMX freewheel.
Taking them apart is a little more difficult, and is usually easier when they're still on the wheel. It can be done with a hammer and an ice pick or anything else with a hard tip that will stay in one of the two pits on the locking ring. Using the pin wrench meant for this is better and a lot easier, but no point buying the tool if you're only going to do it once.
Parktools.com makes good bike tools and has wrenches for both removing and disassembling freewheels, but at a guess it'll cost you at least $40-$60 for the ones you'd need plus shipping, possibly a lot less if you find a good local bike shop that has them. If you have a nice LBS, they might even just take it apart for you and remove the pawls for a cheap one-time fee that'd be much less than the tools cost. Some won't help like that, some will. Never hurts to ask. If you buy the freewheel from them, they might charge even less, and you won't have to pay shipping on the freewheel, either.
Either of the ones you list from Staton are basically identical to what is found on cheap BMX bikes I've gotten from Freecycle for nothing. If I had any working ones left I'd send you one, but I've managed to screw up the threads on the useful ones not already on a project by welding to them in early CrazyBike2 experiments.
Basically if you are letting the BB axle and freewheel bearings take the torque load of pulling on the wheel, then there is less side-loading on the motor bearings, and they'll last longer. Also less shaft side-loading, so if it's not a hard metal it won't be bent out of true by the torque.
So I was doing cost projections and it was really sobering.
So, now I'm at the part where I say "Use what you got as much as possible.". So, I was looking back at the resource that miles linked to in his first post in this thread, and the freewheel's integration made more sense and I saw how he used a sprocket bolted directly onto the freewheel. He wasn't driving through the cranks, though.
So, I'm thinking. Let's focus on the right hand side again - that left stuff adds a lot of additional cost with specialty dual-drive hubs and the such. So, now I'm thinking...
Let's put the freewheel on. Let's take a #25 90 tooth sprocket and make bolt holes and cut it to shape to mount onto the freewheel's 5-bolt pattern.
Let's use spacers as needed and then mount a small 24-tooth chain ring to the same bolts, and then let's run the bicycle chain on the 24tooth chain and go back to the back with the chain ideally on the 34tooth part of the cassette. Problems?
Oh wait... *crash*... what about interference with the chain stays? Oh well, I'll mount the small chain-ring first and then the sprocket to the small chain ring. After that, the pedal just goes in. This way, the motor coasts while the bike coasts, the motor doesn't drive the pedals, but the pedals drive the motor (I don't care.).
I'm guessing I'll still need a RH trials crank.
Doing this and using a 12T motor sprocket, I should be able to achieve a gear ratio of (90/12)*(34/24) = 10.625. While not 12, it sounds good enough to keep motor heat a negligible concern.
Now, the questionable part is: Will the cassette's freewheel be strong enough? If not, I guess I just upgrade it with an ENO.
Also, I take it the freewheel that the chain-ring and sprocket is mounted might also need a "special one" with the pawls removed? If so, that kind of sucks because I don't yet feel any closer to identifying that "special freewheel". EDIT: wait, now that I just read amberwolf's post, the crank-arm freewheel would just act like a bearing. If that's the case, wait... that means the pedals couldn't drive the crankring anymore and that was the point to isolate it from the left crank. So I take it I want to leave the pawls in on the right side. But would that be a problem? Miles suggested it would with an ENO. So this rightside approach wouldn't work at all? But... I just don't see the problem with letting the thing freewheel if all it's doing is turning - if both the chainring and sprocket are bolted to the same freewheel, then the motor power tranmssion doesn't go through the freewheel - it goes through the bolts and the freewheel just needs to be able to spin fast enough.
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Okay, so back to the left side.
Let's mount a larger #25 sprocket on the disc rotor using a modified #25 sprocket to bolt to the disc mounts. Let's mount a #25 90-tooth sprocket to the pawls-removed freewheel (Doesn't have to be ENO - can be standard freewheel since it's essentially a bearing and doesn't transmit power itself.). Then let's mount a smaller #25 sprocket to the same freewheel. A RH trials cranks would be used on the left side.
With a 14T motor sprocket ->(Crank sprockets) 90T-34T->60T (Disc rotor sprocket), that should give a gear ratio of (90/14)*((60/34) = 11.34 which would be good. I already have the 60T #25 sprocket. The motor would regen while the wheel moved, but I don't particularly care. If I really want to pedal without motor assistance (Like say my batteries are dead or something's not working right), I have a feeling I'll pop up the tensioner and remove the chain. With my other ebike, I've absolutely had no problems with the motor's noticeable drag except during an emergency. But, then, I couldn't just pop off the chain like I would with this system.
Now my main worry is.. is the #25 chain(1/4") strong enough? I'll need a rating of at least 1000 newtons (bicycle chain, or 1/2", chain is rated at around 12,000 newtons).
The total cost for that would be.
Right trials crank - $20 (Maybe less if I can find them at the local DIY bike shop.)
#25 90 tooth crank sprocket - $35
#25 34t crank sprocket - $20
#25 14t motor sprocket - $15
Joe-blow freewheel with pawls removed - $30
Maybe another longer spindle? (Is it really needed???) - $40
Spokes and rim for a 20 inch wheel (I'll use my current hub) - $60
20 inch tire - $30
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$250 - That sounds so much better than my original $490 estimate.
So, now I'm at the part where I say "Use what you got as much as possible.". So, I was looking back at the resource that miles linked to in his first post in this thread, and the freewheel's integration made more sense and I saw how he used a sprocket bolted directly onto the freewheel. He wasn't driving through the cranks, though.
So, I'm thinking. Let's focus on the right hand side again - that left stuff adds a lot of additional cost with specialty dual-drive hubs and the such. So, now I'm thinking...
Let's put the freewheel on. Let's take a #25 90 tooth sprocket and make bolt holes and cut it to shape to mount onto the freewheel's 5-bolt pattern.
Let's use spacers as needed and then mount a small 24-tooth chain ring to the same bolts, and then let's run the bicycle chain on the 24tooth chain and go back to the back with the chain ideally on the 34tooth part of the cassette. Problems?
Oh wait... *crash*... what about interference with the chain stays? Oh well, I'll mount the small chain-ring first and then the sprocket to the small chain ring. After that, the pedal just goes in. This way, the motor coasts while the bike coasts, the motor doesn't drive the pedals, but the pedals drive the motor (I don't care.).
I'm guessing I'll still need a RH trials crank.
Doing this and using a 12T motor sprocket, I should be able to achieve a gear ratio of (90/12)*(34/24) = 10.625. While not 12, it sounds good enough to keep motor heat a negligible concern.
Now, the questionable part is: Will the cassette's freewheel be strong enough? If not, I guess I just upgrade it with an ENO.
Also, I take it the freewheel that the chain-ring and sprocket is mounted might also need a "special one" with the pawls removed? If so, that kind of sucks because I don't yet feel any closer to identifying that "special freewheel". EDIT: wait, now that I just read amberwolf's post, the crank-arm freewheel would just act like a bearing. If that's the case, wait... that means the pedals couldn't drive the crankring anymore and that was the point to isolate it from the left crank. So I take it I want to leave the pawls in on the right side. But would that be a problem? Miles suggested it would with an ENO. So this rightside approach wouldn't work at all? But... I just don't see the problem with letting the thing freewheel if all it's doing is turning - if both the chainring and sprocket are bolted to the same freewheel, then the motor power tranmssion doesn't go through the freewheel - it goes through the bolts and the freewheel just needs to be able to spin fast enough.
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Okay, so back to the left side.
Let's mount a larger #25 sprocket on the disc rotor using a modified #25 sprocket to bolt to the disc mounts. Let's mount a #25 90-tooth sprocket to the pawls-removed freewheel (Doesn't have to be ENO - can be standard freewheel since it's essentially a bearing and doesn't transmit power itself.). Then let's mount a smaller #25 sprocket to the same freewheel. A RH trials cranks would be used on the left side.
With a 14T motor sprocket ->(Crank sprockets) 90T-34T->60T (Disc rotor sprocket), that should give a gear ratio of (90/14)*((60/34) = 11.34 which would be good. I already have the 60T #25 sprocket. The motor would regen while the wheel moved, but I don't particularly care. If I really want to pedal without motor assistance (Like say my batteries are dead or something's not working right), I have a feeling I'll pop up the tensioner and remove the chain. With my other ebike, I've absolutely had no problems with the motor's noticeable drag except during an emergency. But, then, I couldn't just pop off the chain like I would with this system.
Now my main worry is.. is the #25 chain(1/4") strong enough? I'll need a rating of at least 1000 newtons (bicycle chain, or 1/2", chain is rated at around 12,000 newtons).
The total cost for that would be.
Right trials crank - $20 (Maybe less if I can find them at the local DIY bike shop.)
#25 90 tooth crank sprocket - $35
#25 34t crank sprocket - $20
#25 14t motor sprocket - $15
Joe-blow freewheel with pawls removed - $30
Maybe another longer spindle? (Is it really needed???) - $40
Spokes and rim for a 20 inch wheel (I'll use my current hub) - $60
20 inch tire - $30
------------------------------------------------
$250 - That sounds so much better than my original $490 estimate.
If by cassette you mean the rear wheel's multi-sprocket cassette, remember that the ENO is a *single sprocket* freewheel, so you will only have one gear ratio at that point (assuming no front derailer). Will no longer be shiftable to change gear ratios for hills vs flats, etc. THere is a Duo so you could still have two sprockets for two ratios,swbluto said:
It's not really a special one, it's just a regular one you take the pawls out of.
My post refers to the posted idea of using the LH drive and using the BB only as a bearing point for one of your reduction stages, without passing any power of any kind from the motor into the pedal drive, which remains functional and unaltered, except for changing the LH crank to a trials crank for the pawl-less freewheel to mount to.
There is no need to alter the RH crank or drivetrain at all.
The only change to your rear wheel is adding the drive chainring that bolts to the wheel. If you already have a disk-brake capable hub that does not have a disc on it, you can simply bolt it there. If you use the disk brake, you'd need to create a mounting adapter that allows the chainring to be to the right of that, far enough away for the calipers to clear it, but not so far to the right that the chain will not clear the tire. If the chainring is smaller diameter than the rotor by enough for the caliper to clear it, it can be much closer axially to the rotor than if the chainring is larger or similarly sized.
Alternately, if you mount the caliper forward of the rotor instead of behind it as is typical, you can use a rotor *as* a chainring or vice-versa, if it is machined to have both rotor surfaces and chainring teeth. The caliper would then fit around the leading edge of the rotor where there is no chain against it's surface.
If you have only a regular rear hub that just has a blank left end and the freehub or freewheel cassette on the right, then you would need to replace that with a disk-brake style hub, or create or buy an adapter that allows securing the chainring to the spokes (as Eric Peltzer did on one of his ebikes). Or create an adapter to space the ring away from the hub a little and drill holes between some of the spokes for mounting screws to hold adapter/chainring to the spoke flange.
