Scooter/bike hybrid

[mickey]

I think Kerf is correct, Doc. A scrubber is turning against the same surface that the tire rolls on. Every inch of the roller surface turning, moves an inch of tire on the road, regardless of the tire diameter.

I think.

 

[Dockspa1]

Ya, I guess that makes sense. I was thinking of it being driven from the center of the wheel instead of outside the wheel. Now if I can just start thinking outside of the box!
Doc

 

[Dockspa1]

Ya know, I gotta stick with my first assumption because nomatter what when a certain size cog turns another sized cog it will differ between sizes. Not very much mind you, with the fractional differences but still it makes a difference. If the drive was a 4" diameter and the wheel was a ten inch then ther would be 2.5 rotations of the drive wheel and 1 rotation of the 10" wheel. If it were a 1" drive wheel then it would be a 1:10 ratio or 10 rotations on the drive wheel per every 1 rotation on the 10" wheel.
Thats my story and I'm sticking to it!
Doc

 

[Alaskavan]

Doc, maybe this will clear it up: you are correct about the ratios, as far as that goes. A 1" roller making say 1,000 rpm, will make a 10" tire perform, what, twice (?) as many revolutions in a given period of time, than it would a 20" tire. However, the roller will move the same distance over the surface of both tires, and the tires would cover the same distance over the ground. The smaller tire would just spin faster getting it done. The deal is, forget about how many rotations the tire makes, It's all about the distance over the surface of the tire.

 

[Hive]

Gear RAtios

This help? http://www.howstuffworks.com/gears.htm

It is fairly basic concept.

 

[kerf]

Dockspa1,
I understand the confusion as this is one of life's little enigmas, so lets look at the numbers.

I have an engine running at 5000 rpm, with a little 1 1/2" wheel attached to the crankshaft. When I put the wheel on the ground how fast does it go?

1 1/2" wheel has a circumference of 4.71239" x 5000 rpm = 23,562 inches per minute.

I use my engine and wheel in a friction drive, with the wheel turning a 26" bicycle wheel. How fast will it go?

1 1/2" roller will require 17.333 revolutions to rotate the bike wheel one time, so at 5000 rpm the bike wheel turns only 288.47 rpm. This is the gear reduction you're looking at but how fast are we going?

The 26" bicycle wheel has a circumference of 81.68" x 288.47 rpm = 23,562 inches per minute.

You will see that the 1 1/2" wheel and the 26" wheel both travel at 23,562 inches per minute or about 22.31 miles per hour.

Hope this helps.

 

[capturedbyrobots]

Ok, we're back on track now!

I made a new drive roller out of steel, and got this thing done, except maybe for some paint....and pipe wrap.
The skateboard roller did not work well for me.
The steel is so much better.

Here's some picts from today.

http://www.capturedbyrobots.com/images/bikeend.jpg

 

[Alaskavan]

What did you use for the roller? (What was it before it became a roller?)

 

[capturedbyrobots]

Oh, I made a thread about making a DIY scrubber in this forum.

It is 2 pipes on top of each other, one at 1 inch OD (Gas pipe)
which fit over the original roller (at .850)
then this pipe, which is 1.25, with an ID of 1in.

So it all fit pretty well, then tack welded together.

The 1.25 pipe was from a scooter steering pole from an old
basket case "Big Boy" scooter I've been stealing parts off of for the past year.
I then went to town with it with a dremel.
It grips great with very little tire wear.

Ya'll should dremel slots in your worn down rollers, and you'll get your grip back.

 

[Alaskavan]

I'll give that a try. I've got a dremel around here somewhere. Thanks.