Jackshaft Better than Jackshafting?

[bakaneko]

Well... 6k rpm with the reduction of 4:1 internally using a standard 10 tooth drive sprocket on a 40 tooth rear on a 26 inch wheel is just going to clear 29mph roughly.. But you have a jackshaft in mind, so if you can use an output shaft on the engine of 10 teeth and use the largest difference in sizes from one sprocket to the next with parts available at sickbikeparts, and using a 34 tooth first gear in a cassette you'll be able to get 27mph (again in first gear) at 6k rpm, I don't know the idle speed or the normal operating speed on the engine you plan to use, but if it's a lot lower you might be OK. Again that math is at a 26 inch wheel.

I think Sram makes a 40 tooth first gear cog in some cassettes, which would give you 23mph in first gear at 6k rpm...

Aye, careful planning will be needed to determine the various sprockets but one thing I like to preserve is the standard cassettes on the bikes. The rider in the video as you might have expected has an oversize 1st gear in his cassette. The jack shaft itself will need to be extended so I am not sure if SBP will have that or it will have to be sourced elsewhere.

I guess in terms of costing it should be the same if not slightly less than a regular 4-stroke kit, but I think the bigger thing is if others would purchase something like this over a conventional direct drive kit. IMO, I think it would solve so many downstream and extended usage problems but maybe that is just me... haha

 

[gary55]

Aye, careful planning will be needed to determine the various sprockets but one thing I like to preserve is the standard cassettes on the bikes. The rider in the video as you might have expected has an oversize 1st gear in his cassette. The jack shaft itself will need to be extended so I am not sure if SBP will have that or it will have to be sourced elsewhere.

I guess in terms of costing it should be the same if not slightly less than a regular 4-stroke kit, but I think the bigger thing is if others would purchase something like this over a conventional direct drive kit. IMO, I think it would solve so many downstream and extended usage problems but maybe that is just me... haha

It eliminates several components from the drive train so a lighter drive train and less parts to go bad has to be a good idea. Probably have to go with the straight shaft engines. Their are plenty of j shaft and clutch suppliers out there. Just need to get the clutch setup with the drive of your choice and figure a way to tension it.. Belt and pulleys would be kinda cool. Quiet and no oil. Automotive type belt and you could get them at the local parts store. The more you look at this the better it looks.

 

[KCvale]

Yes, yes. I know KC your shifting 4-strokes have a direct connection from the transmission to the freewheel via your 10G design and you don't have to monkey around with the jackshaft.

But, for the rest of us with 4-strokes (HS or HF or whatever) and other bikes, as the video suggest can we do without the transmission and just use the jackshaft gearing as the transmission via oversize sprockets.

You can't even start until you have a clutch on the Drive Train.

There is a perfectly good sprocket on the other side of the bike, which is designed to provide torque to the rear wheel.
So, maybe 4-stroke kits can come with the following instead of a transmission and rear sprocket:

- Clutch drum (what tooth?)
- SBP jackshaft assembly (what tooth?)
- SBP free wheel (what tooth?)
- Various chains and tensioners

So you are asking me to fill out a parts order for you?
Best put up a couple good 'today' pics with a bland background of your bike, and sure I'll help you.

 

[gary55]

Yes, yes. I know KC your shifting 4-strokes have a direct connection from the transmission to the freewheel via your 10G design and you don't have to monkey around with the jackshaft. But, for the rest of us with 4-strokes (HS or HF or whatever) and other bikes, as the video suggest can we do without the transmission and just use the jackshaft gearing as the transmission via oversize sprockets.

This is all goes back my dislike of the rag joint and even hub adaptor direct drive rear sprockets. There is a perfectly good sprocket on the other side of the bike, which is designed to provide torque to the rear wheel. So, maybe 4-stroke kits can come with the following instead of a transmission and rear sprocket:

- Clutch drum (what tooth?)
- SBP jackshaft assembly (what tooth?)
- SBP free wheel (what tooth?)
- Various chains and tensioners

The kit will take a lot longer to complete but now we have a system that uses the designed drive train of the bike (right side) and avoid over stressing the wheel, transmission issues, crappy rag join sprockets and even the hub adapter (it seems). The chains are also shorter so alignment would be easier and this method might even be cheaper. Hell, it might even work with single gear bikes with the right gearing.

TLDR, I am just saying the video shows the potential for a new packaging of 4-stroke motorized bike kits with a better usage of the original bike drive train and gearing. Okay, maybe this is just wishful thinking?!

If you want to build your own transfer the video clearly shows you can. It also tells you where to get parts. It also tells you most of the gearing, so I think you should just go for it. It looks more efficient so it should come out bad assed.

 

[bakaneko]

You can't even start until you have a clutch on the Drive Train.


So you are asking me to fill out a parts order for you?
Best put up a couple good 'today' pics with a bland background of your bike, and sure I'll help you.

No, this is just an open ended discussion for the folks on this forum especially those with 4-stroke kits. Obviously, after having the kit for a while and looking at the 4-stroke kit options out there, I feel that (with inspiration from the video) we can redesign 4-stroke kits to eliminate the transmission and rear-direct drive sprocket and replace it with a jack shaft to a SBP freewheel. This will hopefully eliminate a lot of issues with pricey transmissions, over-stressing the rear wheel hub, and that dreaded chain tensioner. As well as the added benefits of multiple gears. Just thinking about it and from other members that have provided good suggestions, this seems possible to do.

 

[Frankenstein]

If you could manage to get a larger right side sprocket for the jackshaft you'd probably be golden, I see a 41 tooth for a 5/8 keyed shaft but that's starting to push it. Maybe a 30 (largest sbp has is 21) would do it, it would reduce the top speed of the first gear with 34 teeth to 19 mph...

Jackshaft extention? what do you mean by that?

 

[bakaneko]

I meant a longer jackshaft. LOL, I am not sure why I would say extension. The SBP jackshaft is designed with an 3-4" offset from the motorized bicycle transmissions. Since we would be running the drive chain directly from the drum the jackshaft would have to be longer. Yeah, I didn't mean to hijack the OP thread about this. Just something I thought about. I have a 4-stroke direct drive atm and it is fine but I do want to try this one day and of course make the part sourcing and research available to everyone.

 

[CrazyDan]

http://www.staton-inc.com would be the place to go for shafts and gears.

 

[KCvale]

I feel that (with inspiration from the video) we can redesign 4-stroke kits to eliminate the transmission and rear-direct drive sprocket and replace it with a jack shaft to a SBP freewheel.
This will hopefully eliminate a lot of issues with pricey transmissions.

You mean like this?

4G case for the HS 142F-1G clutch attached short shaft engine...
5:1 initial reduction that houses the 4G clutch and freewheel 100T pulley.

By freelwheel 100T, I mean when the engine is off you have no drag when pedaling which REALLY helps when you ride out of gas, at night, going uphill, with a pissed off trucker on you butt hehehe ;-}

Oh, and far from least the last benefit, you can easily adjust the belt so it's not 'worn out' in a week, and they do run extremely quite, belts have always been good that way ;}

All I did was press the shaft out of that 100T and get myself a longer one, then press it back in and go from there...

Well, I knew a carrier bearing would be needed where the shaft connected to SBP BB and that was!

This kind of system CAN ONLY BE FOR A SPECIFIC BIKE STYLES!
Lets just say I was all set to sell kits and stopped,
It's hard to do a build like this without your own eyes on it.
Bikes are different.

...but back to tech, thats ~14: 1 to the Intentaranl gears on the rear sprocket.

I can't see where cornrors can be cut but I'm in.

 

[Frankenstein]

You mean like this?

4G case for the HS 142F-1G clutch attached short shaft engine...
5:1 initial reduction that houses the 4G clutch and freewheel 100T pulley.

By freelwheel 100T, I mean when the engine is off you have no drag when pedaling which REALLY helps when you ride out of gas, at night, going uphill, with a pissed off trucker on you butt hehehe ;-}

Oh, and far from least the last benefit, you can easily adjust the belt so it's not 'worn out' in a week, and they do run extremely quite, belts have always been good that way ;}

All I did was press the shaft out of that 100T and get myself a longer one, then press it back in and go from there...

Well, I knew a carrier bearing would be needed where the shaft connected to SBP BB and that was!

This kind of system CAN ONLY BE FOR A SPECIFIC BIKE STYLES!
Lets just say I was all set to sell kits and stopped,
It's hard to do a build like this without your own eyes on it.
Bikes are different.

...but back to tech, thats ~14: 1 to the Intentaranl gears on the rear sprocket.

I can't see where cornrors can be cut but I'm in.

This is pretty solid of an idea, that 5:1 isn't going to be easy on a toothed sprocket, especially with a half inch pitch chain which just tends to become bulky and awkward... The belt solves it cleanly, and pushing that shaft out is just better, cool to know it's even possible, maybe in another 25 years I'll go 4 stroke and I'll keep that idea in mind.

The corners are about as far as they can go you're right, and largely dependent on at least an initial 4:1 reduction but that 5 seems absolutely perfect and ideal on a multi gear bike... The drive shaft just spins too fast to not use a proper gear down, and those speeds are probably better off with a belt, the chain will just make it worse...

Sorry bakaneko, you may just have to give up the unique gear jackshaft try outs and just go with a real transfer case, all in all it will probably reduce the problems you encounter...

Ps: I was wondering how "bakaneko" was already part of my phone's typing dictionary, Googled it it's a Japanese demon cat lol what?