Freewheel gears on a jackshaft, where to get parts?

skyl4rk

skyl4rk

Member
Putting together a parts list for a jackshaft. If possible, i would like to have three sprockets on the jackshaft, one fixed output sprocket that is connected by chain to the rear wheel sprocket, one input sprocket with a freewheel connected with chain to the pedal sprocket, and one freewheel input sprocket to the motor/clutch. This would be used with a 50cc HuaSheng with a centrifugal clutch and a Dax reduction gear (3:1?). It would be used on stretch cruiser or a mountain bike, haven't decided yet.

I still need to work out the tooth counts, but can anyone point me to a source for freewheel sprockets that will mount on a jackshaft? What diameter jackshaft would you recommend for this? Would you recommend a keyed jackshaft?
 
Not sure why you need a third sprocket...

Ohh, never mind, your pedals are nowhere near the jackshaft right?
I suppose that would apply to Jackshaft motorizing a tandem bike with the motor on the back rider spot too right? Let us know what you do please.
 
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Those Daytons look good. Would you happen to know what pitch 415 chain has? I thought it was half inch, but they seem to have a different method for measuring pitch.
 
KCvale said:
Not sure why you need a third sprocket...
Click to expand...

I want to take the pedal chain and the motor chain to the same jackshaft, so that there is one output chain to the rear wheel. The pedal chain would not go to the rear wheel.

It is possible that the bike will be a rear suspension bike and the jackshaft would be at or near as possible to the pivot point.

I would use a fixed hub on the rear wheel. I think I can get up to 22 teeth, maybe more on a fixed hub sprocket.

Right now I am running a Titan, which has a 11 tooth output on the motor, and a jackshaft with 10 input and 10 output to a 44 tooth wheel sprocket. So it is 4:1 from the motor output. There is an internal gear reduction in the Titan motor, which I don't know what it is, but 4:1 reduction from motor to wheel works on a 26" wheel.

So I am thinking of a jackshaft with a 22 tooth freewheel sprocket for motor input, and an 11 tooth output to a wheel sprocket with 22 teeth. 11 teeth to 22 teeth (jackshaft) 11 teeth to 22 teeth.

As usual, due to lack of fun money, this will not happen soon.
 
skyl4rk said:
I want to take the pedal chain and the motor chain to the same jackshaft, so that there is one output chain to the rear wheel. The pedal chain would not go to the rear wheel.
It is possible that the bike will be a rear suspension bike and the jackshaft would be at or near as possible to the pivot point.
Click to expand...
If you are experienced with Jackshaft's please don't take this as talking down to you, but simply sharing basic info for all that that will read this topic.

A jackshaft is a simple thing. It simply transfers the left side drive train to the right side via a shaft and a couple of chains.

These are example pics of my bike I just took, and yes, it has been around awhile and has many miles on it now.

(note these are 800 pixels wide so click them for more detail)

Js1.jpg


Js2.jpg


Once the drive side gets to the right pedal side that chain goes to to the pedal crank via it's second sprocket.

Js3.jpg


The thing is, all you need to be able to still pedal the bike but not have the pedals turn with with motor is to isolate the pedal crank shaft from the sprockets with a single Freewheel clutch.

JScranksFreewheel.jpg


Js2Chainwheel.jpg


That way the motor (which has a clutch) is always direct connected to the rear wheel drive train via the shared sprockets, but the pedals are not as they can free wheel, but still can be used.

(continued in next post)
 
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(continued from previous post)

And then you have the single output drive chain drive both pedal and motor can power.

Js4.jpg


Now if you are going to jackshaft put some gears on!

Mine has an Internal 3-speed hub, but if you want pivoting rear suspention no problem, use a 7-speed derailer gear system. The thing has it's own tensioner so you don't need to worry about chain tension, it self adjusts and you add gears!

I hope that helps you understand why I asked about 3 sprockets, and for everyone else how it works.
 
While chain alignment might be somewhat of a challenge, bringing the two chains to one jackshaft should simplify things, at least on some bicycle designs.

The motor may be located behind the bottom bracket, on a stretch cruiser the bottom bracket is forward and I would prefer moving the motor as far back as possible, maybe even a rack mount. On a tadpole trike the bottom bracket is far forward. I have not chosen a bike type yet, but it will likely be lower and longer than a cruiser.

I'm trying to avoid the motor chain spinning a sprocket right next to my pant leg and shoelaces. I have caught them many times on a pedal bike and don't want to know what happens with a motor powered sprocket.

Thank you for reminding me about the internal hub option, that would make a lot of sense as a way to get a geared system. It does create another challenge since all three chains would be on the right side of the frame. The jackshaft mount would need to be well braced.
 
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Tough to call how you could do it without a bike picked out, but if you are going to make your own frame mounted jackshaft you could just mount two sprockets directly to the end of the shaft, with the one to the pedals on a freewheel.
The wheel would essentially be direct connected to the motor, but the pedal chain and sprocket wouldn't move unless you pedaled.
 
the single shaft design is actually an awesome idea... the motoped puts it to great use! i'm currently looking for parts to build my own... the links posted above seem to be pretty good resources... now i just need to learn machining blue printing and terminology lol

the joys of being a carpenter getting into bike building...
 
Sky & Redneck

Just found your thread today, you may be done by now !!

Staton inc.com has exactly what you need. Years ago it took me awhile to figure out what they were for.

Your pedal crank and sprocket stay in original position without a freewheel sprocket bearing on the pedal crank at the bottom bracket (BB). You may need wider crank to clear motor though.

Staton sells a adapter that goes on jackshaft for $16. it is threaded for freewheel sprocket adapter and the very cool part is that it has 3 grooves for the rear wheel drive sprocket to slide on (costs about $6. several size sprockets available). Then a freewheel sprocket screws onto the adapter holding the thin rear drive sprocket in place.

The freewheel bearing with sprocket can be any size to the size of pedal crank sprocket. Your pedal chain goes to the free wheel sprocket on jackshaft. the pedals do not move when the motor power is used, unless you want to help or pedal the bike.

The motor drives the larger jackshaft sprocket on the left side. The left jackshaft sprocket is where you get correct gear ratio, it could be mounted on a right hand freewheel bearing and right hand threaded adapter and flipped for left hand motor power if a freewheel was desired on both side of jackshaft.

The jackshaft can be mounted several ways in bearings. SBP sells a 4 stroke jackshaft "mount" for $49.. The two 5/8" id bearings by 1- 3/8" od can be bought from them also.

Bought pillow block type bearings that are threaded in the bottom, the bolts go up from under mounting plate, they look much neater.

The rear derailleur is then your transmission gears, like a dirt bike. I bought the parts a couple years ago but have not used them yet.

Forum members don`t seem to realize about the 3 groove adapters and the slide on sprockets. They solve a lot off possibilities.

Checked Staton website last week and he has added more 3 prong sprockets.

Hope this helps. The perfect jackshaft shifter application for any motor.

Ron
 
redneck82 said:
the single shaft design is actually an awesome idea... the motoped puts it to great use!
Click to expand...
The MotoPed design is cool and incorporated into the rear suspension pivot to keep chain angle to wheel true, but it is designed for really wide motors and just not practical to duplicate on a regular bicycle frame.

MotoPedBB2Pedals-750.jpg


MotoPedKickstart2.jpg


Very cool bike frame by the way, I put an 86cc 4-stroke 4-speed in mine.
 
Great bike KC, and from your website, it might be for sale.
A video of you shifting gears would be very enlightening.
 
mat_man said:
Great bike KC, and from your website, it might be for sale.
A video of you shifting gears would be very enlightening.
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Thanks mat_man, it went together pretty well and sure it's for sale as it's too much bike for me these days.

I have a nice Cannon camera but the mode selector broke off so it's stuck in still pic mode, hopefully I have something here to get a video before it's gone.
 
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