How to Strap a Leaf Blower Engine to a Bike and Go Fast

Step 2 Attaching the Spindle

The 1.25 inch spindle with a threaded hole that I used on my bike is a peg which came with my all-terrain scooter. The shaft was already threaded so the spindle was easily tightened onto the shaft and secured with two more nuts. In a spindle driven design, the diameter of the spindle is the only factor that can change the effective gearing of the bike (the tire diameter doesn't matter.) A 1.25 inch spindle works well on this bike as a nice middle ground between top speed and acceleration. It would still be interesting to try out some other sizes.

Comments

[1august11]

ya, i see that your mount is burnt

[marshallmarshall1]

The size of the tire does too matter. gears are always a two part system. there is no one gear unless that one gear is just the tire and you're riding a trike. the peg is like the pinion and the tire the spur. if the tire is bigger you're going to need a bigger peg in order for it to go as fast.

[Prometheus]

When you are using a roller against the tire, the tire size has absolutely no effect. Here's why: The roller is moving against the outside diameter of the tire. The outside diameter is rolling on the road. The tire is only a buffer between the road and the roller. Whether the tire is 12" in diameter or 120" in diameter, the speed is the same, no matter what. A 20T gear driving a 350T gear driving another 20T gear is still a 1:1 ratio. Remember that the tire is acting on the ground as the final drive, and also that last spur gear, hence any gearing prior to that without an actual reduction is still the same ratio.

[Jnkyrdguy]

True, normally changing either gear would change the final drive ratio and the resulting speed of the bike at a given rpm of the engine. But this is a special case since the second "gear" rides on the ground. When you change the size of the tire it effectively changes the gear ratio, but it also changes the distance the bike travels every time the wheel rotates one revolution. For example, if I changed out the current tire for one that's half the diameter the new wheel would spin at twice the rpm, but the bike would also go half the distance per revolution of the tire. This results in the same distance traveled for the bike per rotation of the engine regardless of the size of the tire.

[Prometheus]

Sorry, but absolutely wrong! You have to remember that this is driving the surface of the tire at it's outside point. If it were driving the wheel by the hub, you would be right, however the wheel in question is merely an idler between the driven roller and the ground. You are mistaking your basis for a mechanical advantage.

[Prometheus]

To add, a wheel that was half the diameter turns twice as fast, but travels half as far, hence the tire size you put this roller to is irrelevant to the actual ratio.

[Jnkyrdguy]

I think we're saying the exact same thing here just in different ways. You even used the exact same example as my second paragraph. I called it a "gear" which it isn't, but it still works out if you look at the system as a pair of gears, keeping in mind that the second "gear" is also the tire and won't change the final drive ratio to the ground if you change its size. Changing the spindle size does change the drive ratio just like changing a gear would. (ie: halve the diameter of the spindle and you will go half as fast with twice the force to the wheels, the same if you halved the diameter of the pedal's drive sprocket on the same bike)

[marshallmarshall1]

I guess i didn't think that out thouroughly. You are correct though. sorry about that.

[Medways man]

Hey junkyard...me and my dad are working on the project right now and we have run into the first problem...the peg is too big to thread onto the shaft.

[Medways man]

is a very small looking peg but thw hole is too big i guess

[tomcat955]

get a mongose peg

[Medways man]

well we just got back from an auto body and they welded it so now we have that on now we just need plywood on.