# Motor with no gear reduction?

Discussion in 'Friction Drive' started by boyntonstu, Jan 28, 2015.

1. ### boyntonstuMember

Using GearRat to calculate bicycle speed, there is no gear reduction included between the motor and the tire.

Can you run a motor direct?

you could run a motor directly but not an engine i guess...

wt?

gearRat?

3. ### boyntonstuMember

well, having opened gearrat and finding that its just a ratio calculator, i ponder on your original question...

seems to work fine for me.

its for calculating estimated speed from a given tyre diameter, a given motor (engine) speed, and whatever ratios you choose to punch in.

is it really that hard to figure out?

once again....i wonder about the question in the first place...

5. ### troygMember

I doubt it, he's been here since '08, and look at the trike he built (in the for sale area), that's a skill set I don't see coming from robot.

hmmm...interesting....

re-reading and noting that this is in friction drive makes me refute my earlier statement...

hmms. yes, the engine can run direct in friction drive. you have to consider the diameter of the roller only. think of it as the wheel running along the ground. the tyre itself, well...its speed is exactly the same as the ground its rolling along. so we can ignore tyre diameter for friction drive setups.

get the roller diameter right and the gearing will be right. basically, around 1" diameter is good.... smaller for hills and power, bigger for speed.

or pi x 1" = 3.14 inches of travel per revolution of the engine. times that by rpm and remove the necessary zeroes to get speed in mph, kmh, kn, parsec...iunno...

hint... 1/2" external star washers make excellent rollers 7/16 or larger, i never tried.