SMALL Trimmer Motor 30cc'ish Bicycle Gearing + 370lbs, reasonably doable?

matt4x4

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What I am looking for precisely is a very small engine, that will "assist" me on very long, flat, stretches.


Installing a 30cc'ish trimmer motor with proper gearing - motor 10T to wheel 50T+
Is it possible doing a good warm sunday cruising speed (25-30kph/16-19mph) on flat ground and 370lbs total weight.

I know I've seen gears from industrial supply up to 90T, also electric mid drive stores have lots of gearing choices, go karts etc, so I dont think gearing would be an issue. How easy they are to adaptable to the spokes on the wheel, or disc mount, is solvable.
Perhaps a speed bump I would run into is how to get a suitable gear sprocket onto the 30cc trimmer motor.
 
Installing a 30cc'ish trimmer motor with proper gearing - motor 10T to wheel 50T+
Is it possible doing a good warm sunday cruising speed (25-30kph/16-19mph) on flat ground and 370lbs total weight.

I know I've seen gears from industrial supply up to 90T, also electric mid drive stores have lots of gearing choices, go karts etc, so I dont think gearing would be an issue. How easy they are to adaptable to the spokes on the wheel, or disc mount, is solvable.
Perhaps a speed bump I would run into is how to get a suitable gear sprocket onto the 30cc trimmer motor.
10 tooth to 50 tooth on a 26" wheel at Only 5000 rpm is Only 77 mph and that motor revs higher than 5000
That proper gearing will be an issue.
Even a 90 tooth will be 43 mph
A 150 tooth will bring it down to 26 mph
And a 30 cc trimmer pulling 370 lbs is very ambitious.
 
What I am looking for precisely is a very small engine, that will "assist" me on very long, flat, stretches.


Installing a 30cc'ish trimmer motor with proper gearing - motor 10T to wheel 50T+
Is it possible doing a good warm sunday cruising speed (25-30kph/16-19mph) on flat ground and 370lbs total weight.

I know I've seen gears from industrial supply up to 90T, also electric mid drive stores have lots of gearing choices, go karts etc, so I dont think gearing would be an issue. How easy they are to adaptable to the spokes on the wheel, or disc mount, is solvable.
Perhaps a speed bump I would run into is how to get a suitable gear sprocket onto the 30cc trimmer motor.
id run a rear wheel friction drive setup. these trimmer dont have a lot of power to begin with (a average one makes about 1/2hp)
so you have a proper gear ratio.

if you want a good rear wheel setup, try to find a 85cc techumseh 2 stroke (most common in snowblowers)
and then get a 20" bike rim and then ether bolt it on or weld it on to a 26in bike. and figure out a clutch for the belt drive.
then you would have more than enough power to go up hills, and be able to go around 45mph. (if you remove the govener)
 
Friction direct drive off the clutch carrier of the weedeater engine would work, if this is what your looking for.

I'd use a 1"~1".125 diameter steel BMX freestyle type peg. simple and easy to fabricate.

If you insist on going with gears, you'll need to fabricate some sort rear rack solution using a dual reduction set of gears. Getting the sprockets, especially the little #25 sprockets interfaced with the rear wheel will be the problem. There's not a lot of torque in a 30cc engine and they need at least 20:1 gear ratio if not 24:1 to have enough push for your weight. even more reduction if you want to climb slight grades.

My bike is 26:1, belt reduction friction, it pulls a single wheel trailer and I only weight 160# and I often find the engine struggles against 25 mph headwinds on the flat. It's a 30 cc McCullough ProScaper.
DSC00020.JPG
 
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