How to run bearings in this set up?

[RocketJ]

I hope you get this all sorted to your satisfaction & that it eventually works wonderfully Rocket.

The go cart transmission adds a sizable complication to your build both mechanically and visually that would be hard for me to justify even if successful. However it's your project & no one else's so again I wish you great success!

Rick C.

Thanks, Rick. I know my project is absurd and most people would take a look at it and say "why not just run it without the gearbox?", but I'm too stubborn not to try it haha. If I can get it to work properly, I'll make sure it looks just as visually appealing. I don't want to half ass this build like I and others have done in the past. I think the reason for such a complicated build goes beyond trying something new. I'm not sure exactly why, but I feel the need to attempt something that others have wondered about doing and hopefully proving that these types of builds are possible.

 

[RocketJ]

I agree with Rick.

Your transmission is unique and purposeful.

I hope you get this to work well.

I’m also involved in a nerve racking 212 project similar to yours:

how to run power thru the bottom bracket, but keep the pedals functional.

It is painfully satisfying.

I'm honestly not sure how people do it, but I know you can use the pedal crank as a function pedal and a jack shaft. I think Pat sells the crank mechanism for it. Maybe message him?

 

[indian22]

Look at the original moto-bikes circa 1903 thru 1920 or so. The bottom bracket was used on all single speed/reduction gear models not just board track, but road bikes as well. Most had the capability to pedal as well, though the purpose built factory racers had the pedals blocked off to use as pegs. They used the bottom bracket because it was simple and worked really well, not need for a separate jack shaft bolted or welded on. The Sportsman bikes run a really well constructed version of the originals and guess what it's simple to install, works great and looks clean and is faithful to the classic bikes.

I machined my own version of the bottom bracket bike, except for the sprockets and lock collars for my Peashooter and Simplex, along with the reduction gear & they work great, but I could have used the Sportsman setup and saved money with the Peashooter. The Simplex required some unique changes however.

Still it all boils down to what you want and are willing & able to fabricate. The bottom bracket is just an easy, practical and clean installation for any style bike but especially one that actually looks vintage road or racer.

Rick C.

 

[5-7HEAVEN]

I'm honestly not sure how people do it, but I know you can use the pedal crank as a function pedal and a jack shaft. I think Pat sells the crank mechanism for it. Maybe message him?

Yes, Pat’s version is a functional jack shaft, and his pedals work.

However, if you gaze intently at a picture of his bike, it doesn’t seem like his engine power runs thru the bottom bracket to the right side.

Pat seems to be using the chain rings on the left side as a jack shaft.

The drive chain then routes to the left side rear sprocket.

His pedals function because the jack shaft chain rings on the left side are idler sprockets that’s connected to each other.


That means the chain rings are spinning on the shaft on freewheels.


Notice that the pedal arms are directly connected to the spindle. That’s the dead giveaway that engine power is not flowing through the BB.

 

[5-7HEAVEN]

I'm honestly not sure how people do it, but I know you can use the pedal crank as a function pedal and a jack shaft. I think Pat sells the crank mechanism for it. Maybe message him?

Rocket, that’s the part.....

Very few people have run engine power THROUGH the bottom bracket (BB) and kept functional.pedals.

I haven’t seen it happen on these forums in 15 years.

It seems easy to do, but it’s not.

Engineering problems occur, as you know.

Even if you were to perfectly align the engine sprocket and chain ring, you wouldn’t have a low enough gear ratio to power the engine decently through the bike’s gears.

And if you don’t use a jack shaft to align your clutch and chain rings, your engine sticks out too much on the right side.

A 2-stroke engine might need 35:1 or better gearing before transferring power through the BB.

My 212 engine needs 9:1 gears thru the BB to drive my 7th gear effectively.

Without a jack shaft, I’d need a 10t clutch with a 90-tooth chain ring sprocket!

So sending power through the BB is one issue.

Gearing it to high potential is key.

You’ll hear people say “It runs so-so, but it runs powerless in the last 3 gears.”

Orrr “The engine won’t kick in, until I’m pedaling 15mph!”

I’ve only seen one example of running engine power thru the BB with functional pedals on YouTube.

Oddly, the owner never displayed or explained how his setup worked.
I questioned him in his comments section; he didn’t respond.

 

[5-7HEAVEN]

I’m embarrassed to say that I haven’t had the pleasure of reading Indian’s article on his Simplex bike.

I’ll get to it soon!

 

[indian22]

Here's the breakout on how the bottom bracket works. Two sealed bearings are inserted into the bottom bracket "shell" I use a 3/4" pedal shaft with either cottered or J.A.P taper machined on the ends to attach the pedal levers. I machine "snap ring" grooves on the shaft just outside of the bracket bearing this prevents any shaft movement side to side. I'm not going to describe the individual machining operations. All the pedal side components are locked solid to the axle shaft, so when the pedals turn the axle, the pedal sprocket turns. The rear hub sprocket has a freewheel attached as is normal on a pure pedal bike. The pedal side of the axle operates exactly like a normal single speed pedal bike & the entire axle spins free in the bracket housing on bearings. The freewheel allows coasting with dead pedals as normal in this type setup.

The left side of the axle is completely smooth with no machining added except for the snap ring and pedal lever connection previously described. Then a reduction gear with two 3/4" shaft bearings is machined, with a larger primary chain sprocket on the out side that lines up with the motors output sprocket & another sprocket with bearing is offset enough that this inside small sprocket lines up with the final drive sprocket on the hub forming the secondary chain line. The reduction sprockets form a single unit and are connected together in the bracket housing. The reduction sprocket assembly comprise a unit & are free to spin on the shaft driving the two chains and the rear wheel. The width of the sprockets has to be perfect or the two chain lines won't be straight.

The motor does not turn the pedal bracket axle. Only using the pedals can turn the bottom bracket housing axle. The motor can't

This setup allows the riders to assist the motor to propel the bike with or without the motor running. If a coaster type hub is employed the pedal side chain still actuates the brake mechanism. The rear freewheel is critical to proper function set up in this manner. However both drum or disc brakes can be used with the bottom bracket/freewheel/reduction gear setup and has worked well for 120 years or so. This isn't a new idea it's an old technique that works well.

If you have a lathe & mill you can build one. I'd prefer to buy my next one however!

Rick C.

 

[indian22]

Every Sportsman bike and two of mine are powered by bottom bracket reduction gears. As have countless forum bikes and original moto bikes manufactured for the last 120 years. These are single speed reduction setups.

Now if you are running any kind of "jacked power" down the pedal side with the 212 and through a "shift kit " you do need a lot of design skill & freewheel wizzardry. Tony and some others have done some amazing work with these type of setups and I think they achieved pretty good results and dependability as well.

Rick C.

 

[5-7HEAVEN]

Here's the breakout on how the bottom bracket works. Two sealed bearings are inserted into the bottom bracket "shell" I use a 3/4" pedal shaft with either cottered or J.A.P taper machined on the ends to attach the pedal levers. I machine "snap ring" grooves on the shaft just outside of the bracket bearing this prevents any shaft movement side to side. I'm not going to describe the individual machining operations. All the pedal side components are locked solid to the axle shaft, so when the pedals turn the axle, the pedal sprocket turns. The rear hub sprocket has a freewheel attached as is normal on a pure pedal bike. The pedal side of the axle operates exactly like a normal single speed pedal bike & the entire axle spins free in the bracket housing on bearings. The freewheel allows coasting with dead pedals as normal in this type setup.

The left side of the axle is completely smooth with no machining added except for the snap ring and pedal lever connection previously described. Then a reduction gear with two 3/4" shaft bearings is machined, with a larger primary chain sprocket on the out side that lines up with the motors output sprocket & another sprocket with bearing is offset enough that this inside small sprocket lines up with the final drive sprocket on the hub forming the secondary chain line. The reduction sprockets form a single unit and are connected together in the bracket housing. The reduction sprocket assembly comprise a unit & are free to spin on the shaft driving the two chains and the rear wheel. The width of the sprockets has to be perfect or the two chain lines won't be straight.

The motor does not turn the pedal bracket axle. Only using the pedals can turn the bottom bracket housing axle. The motor can't

This setup allows the riders to assist the motor to propel the bike with or without the motor running. If a coaster type hub is employed the pedal side chain still actuates the brake mechanism. The rear freewheel is critical to proper function set up in this manner. However both drum or disc brakes can be used with the bottom bracket/freewheel/reduction gear setup and has worked well for 120 years or so. This isn't a new idea it's an old technique that works well.

If you have a lathe & mill you can build one. I'd prefer to buy my next one however!

Rick C.

Thank you for explaining your excellent engineering work.

Yours is like Pat’s;
You’re using the BB as a jack shaft, like board track racers did over 100 years ago.

And like them, no engine power was transmitted through the BB to the right side of the bike.

It works for you, Pat and the racers of yesteryear, but it’s not for me.

Like Rocket, I’m on a personal quest to do what no one I know has ever done.

for personal satisfaction.

 

[indian22]

7th. I apologize to you as well because I joined this thread late and didn't realize you were working on a Shimano style/jack shaft gear train build, my comments were directed to those using a very traditional single speed & to Rocket as an alternative to the go cart tranny.

Best luck on your project as well.

Rick C.

 

[5-7HEAVEN]

RocketJ, I follow “Oliver Motorized “ on Youtube.

That guy is a mad scientist/Mad Max on motorized bikes!

I’ve picked up a few tips from him.

 

[5-7HEAVEN]

7th. I apologize to you as well because I joined this thread late and didn't realize you were working on a Shimano style/jack shaft gear train build, my comments were directed to those using a very traditional single speed & to Rocket as an alternative to the go cart tranny.

Best luck on your project as well.

Rick C.

Lol, no problem, Rick!

We’re all mad scientists!

 

[Tom from Rubicon]

#67, Ricks description of a Sportsman Flyer reduction drive, is verbatim Pat Dolan Sportsman Flyer,

As described, a pure Indian transmission of the early 20th century.

If you just used a tuned Bully clutch out-put to a Flyer reduction drive powered by a 212cc engine, A additional reduction drive should not be needed. A 212’cc has lots of torque.
Awaiting future photos.
Tom

 

[5-7HEAVEN]

Any updates?

 

[RocketJ]

Any updates?

It's coming out really well. I'll upload a pic of the progress later today.

 

[RocketJ]

Her'es a few pics. The chain tensioner is just a mock up. I'll add a 3 point system later. I should have the gearbox system tested later this week.

 

[Ralph hop]

Looking good! What's the forks you have, custom built or? If you're thinking of having foot pedals and a side car, incorporating a crash bar that runs down and back would be a good place for mounting both. The engine seems to be leaning a bit forward, it could cause some issues with oiling maybe.

 

[5-7HEAVEN]

Her'es a few pics. The chain tensioner is just a mock up. I'll add a 3 point system later. I should have the gearbox system tested later this week.

That last pic explained a lot to me.

You shouldn't need a Bully clutch.
A regular clutch will work.
Calculating a low gear ratio using your transmission is easy peasy.

 

[RocketJ]

Looking good! What's the forks you have, custom built or? If you're thinking of having foot pedals and a side car, incorporating a crash bar that runs down and back would be a good place for mounting both. The engine seems to be leaning a bit forward, it could cause some issues with oiling maybe.

the fork is a replica girder fork. I plan on building a detachable sidecar after I'm finished. The engine should be fine. Many builders run it like this. It just requires a few extra ounces of oil.

 

[RocketJ]

That last pic explained a lot to me.

You shouldn't need a Bully clutch.
A regular clutch will work.
Calculating a low gear ratio using your transmission is easy peasy.

I was skeptical too, but after seeing it put together like this I don't think it'll be much of an issue. We'll see next week