Weed Whacker Powered Bicycle!

[eagle5953]

What sort of MPG rate can you get on this? Range?

who cares? its fun.

I know it's fun, but it can be practical too. Googling showed that they can achieve upwards of 250 mpg.

[bicostp]

Yeah, but the problem is it could be called a motor vehicle and have to be registered and insured, depending on your jurisdiction and whether or not the cop that pulled you over has met his quota for the day.

Good job! If you build another one, I highly recommend chain drive, since it's more reliable. However, in order to use chain drive you need a motor with a clutch, so you can stop without stalling the motor or lifting the rear wheel.

[Kurt_]

It really worries me that you still have coaster brakes on this thing. Also, that in addition to coaster brakes, you only have front brakes. So in an emergency, even something like avoiding a squirrel, your choices are flip over the handlebars or lock up your wheels instantly. And flip sideways. I seriously encourage fitting rear brakes.

Also, MPG is probably badass. I could see it getting 100 mpg easy. Perhaps 150 or even 200. Run it dry, pop a quarter gallon in, and drive a specific route. Then pop it in to google maps.

[dragonhead]

man all you people worry too much about trivial crap. let the kid ride his bike.

[ttsgeb]

It really worries me that you still have coaster brakes on this thing. Also, that in addition to coaster brakes, you only have front brakes. So in an emergency, even something like avoiding a squirrel, your choices are flip over the handlebars or lock up your wheels instantly. And flip sideways. I seriously encourage fitting rear brakes.

Nonsense, When have you ever locked up a tire using cantilever brakes? Also, any kid who's ever had a bike with coaster brakes knows how to lock them up and not flip over on their side, I remember having contest to see who could skid the longest. IF a real emergency comes up he's not gonna be any less safe because of the brakes, it's more likely to be because of the small plastic gas tank strapped to the back of his bike.

For the record, My bike only has front brakes, and they don't even have much grab, but I've been riding it safely and at relatively high speeds for years.

[dragonhead]

It really worries me that you still have coaster brakes on this thing. Also, that in addition to coaster brakes, you only have front brakes. So in an emergency, even something like avoiding a squirrel, your choices are flip over the handlebars or lock up your wheels instantly. And flip sideways. I seriously encourage fitting rear brakes.

Nonsense, When have you ever locked up a tire using cantilever brakes? Also, any kid who's ever had a bike with coaster brakes knows how to lock them up and not flip over on their side, I remember having contest to see who could skid the longest. IF a real emergency comes up he's not gonna be any less safe because of the brakes, it's more likely to be because of the small plastic gas tank strapped to the back of his bike.

For the record, My bike only has front brakes, and they don't even have much grab, but I've been riding it safely and at relatively high speeds for years.

thank you. the fact that you even needed to explain that is pretty sad though.

[Kurt_]

I haven't used coaster brakes since I was a kid. And I still have a pebble embedded in my hand from when I hit them accidentally going fast downhill. My bike landed on top of me.

No production bike would ever have only coaster and front brakes. It's just an obviously flawed design choice.

[vskid]

Sweet job. I'm sure you're the envy of all the little kids in your neighborhood.

There is a 13:1 gear ratio so acceleration isn't too great, but top speed is very high.

Actually, the bike tire's size does nothing to change the gearing, its just an idler. If you put the bike peg directly on the ground, it would spin just as fast at a given speed (no, I wasn't smart enough to notice this, I read it in a comment on an Instructable about building the same thing). So changing tire size won't do anything, only changing the peg diameter will make a difference.
And like bic said, you should find out if its legal/what you need to do to make it legal.

[Mario]

It really worries me that you still have coaster brakes on this thing. Also, that in addition to coaster brakes, you only have front brakes. So in an emergency, even something like avoiding a squirrel, your choices are flip over the handlebars or lock up your wheels instantly. And flip sideways. I seriously encourage fitting rear brakes.

Nonsense, When have you ever locked up a tire using cantilever brakes? Also, any kid who's ever had a bike with coaster brakes knows how to lock them up and not flip over on their side, I remember having contest to see who could skid the longest. IF a real emergency comes up he's not gonna be any less safe because of the brakes, it's more likely to be because of the small plastic gas tank strapped to the back of his bike.

For the record, My bike only has front brakes, and they don't even have much grab, but I've been riding it safely and at relatively high speeds for years.

Indeed. Braking isn't a big issue on this bike. The front brakes don't have much grab, so you can't flip the bike with them. They do help greatly in braking, though.

[GoldenfrankO]

I was thinking of doing this as well. Sick job on it! BTW I sent you a friend request, favorited the video, and rated 5 stars!

[blaze3927]

nice
cough "temporary citizen"

[bicostp]

cough "temporary citizen"

What's this for?

[dslitemodder]

You might want to add a chain instead of using what you have now. The reason being is that the thread on the tire is going to ware out quick and you will have less traction. Less traction = less control and harder braking.

cool project though

[HBN]

There is a 13:1 gear ratio so acceleration isn't too great, but top speed is very high.

Actually, the bike tire's size does nothing to change the gearing, its just an idler. If you put the bike peg directly on the ground, it would spin just as fast at a given speed (no, I wasn't smart enough to notice this, I read it in a comment on an Instructable about building the same thing). So changing tire size won't do anything, only changing the peg diameter will make a difference.

That's not true. Your talking gear ratios, and thats something I'm REALLY good at (I have a history of robotics, and other such things where it's used a LOT). I made a diagram for ya to explain it better:



Also, while the "wheel" RPM goes up, the acceleration goes down. Even more drastically when you start using reverse-ratios. For acceleration, a smaller input (peg), or a larger output (wheel) is best (Meaning you have a higher acceleration this way than you would if you used something larger, Mario. 13-to-1 is actually pretty good. I might have aimed for 20-to-1, though.). For speed, you want a larger input, or a smaller output. Try to keep a nice balance between acceleration and speed. Especially when you're using a clutch-less design. You'll want a higher acceleration namely because it will reduce stress on the engine when revving up. If you have a clutch, then this isn't as much of an issue because the clutch will slip a little if you allow it too. Giving you a sort of second throttle control, and allowing you to ease the engine into that ratio.

Hope this helps you understand better.

[ABCinc]

I want to make one now... I guess my SNES project is on hold, oh well.
But I'm pretty sure it's legal, unless it can go over 50, well that's how it works around here, but you might get in trouble for riding it around on public roads.