Friction Drive Obsolete With Double Right-Sided Drive

Mike St

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Jun 16, 2008
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Well, this my second bike using the inexpensive, light weight 5:1 scooter gearbox
and a double right-sided drive. This gearbox has a flat front face on the drive side
which allows attachment of ordinary hardware store "L. s," then the motor/gearbox
can be bolted to a motor mount which attaches to the bicycle frame.
Here's the gearbox: https://www.monsterscooterparts.com/trfor3336434.html
The concept allows conversion of engines that do not have fastening points at their base
to chain drive. Any motor 2 or 4 stroke that fits the gearbox can be converted
to chain drive. Here's a link to the first bike I did using steel staton supports for
the rear of the bicycle motor mount:

Here's the advantages of the concept:
1. All weather chain drive.
2. Motor is positioned closer over the wheel than friction drive.
3. Since there are two independent free wheels, with the motor off
it rides freely like a bicycle - no clutch drag.
4. Wide selection of gear ratios; drive sprockets, 8mm, come in
10,11, 12,14,17, and 25 teeth, and the 8mm wheel sprocket is available
in 44,54,63, and 72 teeth. I have used a 11t drive, and 44T wheel sprocket
for an estimate top speed of 24 mph, but far higher top speeds are
possible with different combinations, like 40-50mph.
Bike 6.JPG
Bike 5.JPG
Bike 4.JPG
Bikethree.JPG
biketwo.JPG
bike one.JPG

5. Accepts a wide variety of motors, like Honda GX50, GX35, Subaru EHO 35,
Tanaka PF-4000, and 3000, and Zenoah G43L.
6. No chain tensioner is required.

The drive is built by:
1. Removing the multi-speed cassette.
2. Screwing on a freewheel with the rear 8mm sprocket bolted to it.
3. Inserting a 1/8 inch spacer washer over the first freewheel (from McMaster-Carr).
4. Screwing a single sprocket bicycle freewheel.
5. Using an 8mm chain.
NOTE: The basic frame mount has to be made of aluminum back with steel angle iron or just
use steel angle iron. The mount here is back with angle iron.

Here's some pics:
 

Sidewinder Jerry

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Mar 14, 2011
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Good engineering, however cassettes and freewheels aren't interchangeable; they're completely different types of hubs. What you changed is a multi cog free wheel.

I'm assuming you have 26" tires. If your bike is using 24" tires it'll have a top speed of 25 mph. With your set up you've got a 20:1 reduction. For your current set up with the RS35 the top speed would be:

(7,000×26×π)÷(1,056×20)=27.0724366929.

If you're a light weight under 200 lbs with a Honda 50 series you could go as low as a 16:1 reduction and get around 33 mph on 26" tires.
 

Mike St

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Messages
728
I purposely chose the gear ratio for a top speed under 30, but that's what so good
about the 8mm gearbox. You can vary the sprockets and choose your own
preferred level of performance and drive with a chain. Makes friction drive
obsolete. No this is a 24 inch bike, using a top rpm of 6800, not 7000, the
top speed is estimated at 24.2 mph.
 

Sidewinder Jerry

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Messages
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I purposely chose the gear ratio for a top speed under 30, but that's what so good
about the 8mm gearbox. You can vary the sprockets and choose your own
preferred level of performance and drive with a chain. Makes friction drive
obsolete
With the RS35 about the lowest you can drop the reduction is 18.75:1. Even then you're going to need to be a lite weight and be a flat lander for a speed of 29 mph on 26" wheels on level pavement. Without increased horsepower and/or weight reduction simply increasing the gear ratio won't increase the speed.

I know this because I have a RS35 on a shifter bike. For example if on level ground in a certian ratio I'm doing 7000 rpm at WOT going to a higher ratio the speed will stay the same but the rpm will drop putting the engine under engine strain.
 

Mike St

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Jun 16, 2008
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728
I'm not at all worried about top speed or torque. If I was, I really would choose a more
powerful engine. The RS is only 1.6 HP. The calculated speed is only an
estimate of speed. Of course, other factors enter into actual top speed
like the wind, the incline if there is one, the weight of the rider, etc. But it's
a great help in selecting sprockets. FYI, I live in a flat area and I am under
200 lbs. Guess I'm lucky.
 

Sidewinder Jerry

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The RS35 engine manual states 1.6 hp is produced at 7000 rpm.


20220426_113844.jpg


(7,000×24×π)÷(1,056×20)=24.9899415626 mph.
 

Mike St

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Messages
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Correct, it states top rpm at 7000 for this motor, but I normally
use 6800 for 4 strokes. You're on top of your game and will
catch me if I overlook something. Good thinking!
 

Sidewinder Jerry

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Messages
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Correct, it states top rpm at 7000 for this motor, but I normally
use 6800 for 4 strokes. You're on top of your game and will
catch me if I overlook something. Good thinking!
I've been using my RS35 for 12 years now. Here's my speed formula:

(RPM × Wheel Diameter x π)÷(1056 × Total Reduction) = MPH.
 

Mike St

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Jun 16, 2008
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728
Say, maybe you can help me. My RS is running a little rough, and has to
be really warmed up to get there. What do you suggest? I'm about
to install a new spark plug, and if that doesn't work, maybe a new
carb.
 

Sidewinder Jerry

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Messages
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I like the RS35 for the same reasons you do. It keeps you under 30 mph on level ground. So my local treat me more like a bicycle. Still I fully obey all the traffic laws.
 
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