Dual side freewheel crank?? No jackshaft needed!

[mbatl]

You need 2 right hand cranks because the rh one has the threads to mount the freewheels. The left one does not. It simply slips onto the square shaft.

They make cheap, low-quality left-side Chinese pocket bike freewheels. Unsure if there's high-quality White Industries left freewheels. Then you'd have to machine the right arm to accept left-hand threads.

Once, I installed my right-side freewheel backwards on the crank arm. Then it acted like a left-hand freewheel. It is EXTREMELY difficult to remove the freewheel from the crank arm. Locktite and pinning the freewheel to the arm would lock it in good to work on the left side. The engine would always be trying to loosen/unthread the freewheel, so you need to prevent that.

The left-side crank MIGHT have to be extended further out. Also unsure if the engine and chainring sprockets would line up.

Also unsure if the chain would run from engine to chainring, even with the cover removed.

If everything aligns, then a 10-tooth engine sprocket and 48t chainring would be 4.8:1 x 4.1 engine = 19.68. A standard shift kit has gearing of (4.1 x 1.7) x (44t/10t) = 30.67:1, BEFORE connecting to the rear cassette. By the time it got to the 32t 1st gear on an 8-speed cassette, the weakest combination of a 30t chainring and a 32 1st gear would be 29.44:1.

If you could fit a 9t on your engine and use a 52t on the left chainring, that's be 23.68:1.
Then with a 24t right-side bicycle chainring and a 34t 1st gear on the rear cassette, you'd be okay with 33.56:1. Using a 22t chainring would give you 36.61:1 gearing.

Eighth gear would be 11.84:1, comparable to a 29-tooth rear wheel single sprocket on a Happy Time install.

It is always advisable to gear your bike as low as possible. In doing so, you get a granny gear for very steep hills. You also get to use 7th or 8th gear as a highway cruising gear. I use a Tanaka engine with a shift kit. My 1st gear is 46.36:1, which I find VERY handy. My 8th gear is 15:1, which is also very usable.

Thanks for sharing your experiences.

Haven't replied because I'm researching to see if the freewheel concept is worth the effort compared to constructing a jackshaft somehow on a dual suspension frame.

My sbp jackshaft may work with some modification in how it is secured to the frame since the ht motor wont be supporting it.

*Just give ideas to others who it may help, my plan was to use the staton axle mount assembly and instead run a chain forward to the left freewheel transferring power to the right side dereailer. This would allow the use of my otherwise limited use robin 35cc that is very reliable. Sounds crazy?

[MotoMel]

If you are still interested in this solution, we've virtually finished the design on a crank system that operates as you describe. You can see it at BikeMotive.com or youtube.com/bikemotive. We are now scouting around for economic production. Would enjoy hearing from you.

[Neon]

I know i'm going to regret asking this, but what would be the cost of the crank system as is ? If you haven't already i would get a patent on your design as quick as possible.

[thearcticfisherman]

You need to think out side the box!!!!!!!!!!!!!!!! Grubee just needs to make a right side drive, clutch on the left. TA DAAAAAAAAA!!!!

[MotoMel]

Sorry I missed this a month ago. Cost in prototype quantities is around $2K. Ouch! Gotta get it down, gonna get it down! Patent is pending; investment into the engineering and 4 rounds of prototypes ran *well* into 5 figures. Real ouch!

I know i'm going to regret asking this, but what would be the cost of the crank system as is ? If you haven't already i would get a patent on your design as quick as possible.

[lowracer]

How about putting a 135mm offset fork (Surly Pugsley/Moonlander) onto a bike or stretch a 100mm fork using some threaded rod w/nuts to 135mm & install a rear wheel into the front fork. Then drive the largest cassette sprocket (32 or 34) from a front rack (or DAX/BMP channel) mounted engine using a 5:1 pocket bike transmission w/10 tooth sprocket & some fixed gear chain (Sram PC-1). Keep the rear for pedaling & the front for motoring. When you let up on the gas the front wheel will freewheel, the clutch disengage, for better fuel economy & less clutch pad heat & wear.
I'm actually thinking about doing this since I got a 5:1 transmission recently (bonus w/engine purchase) & it seems to be a solid unit.
-Lowracer-