Has anyone done anything interesting with bicycles? Has anyone make a bike into a stationary bike for exercise or as a power source (for either mechanical or electric power)? Has anyone attached a small gasoline engine to a bike? I saw some bikes like this online. I understand they can get them up to highway speeds.

Human power is actually pretty pathetic, an average person can put out only a couple hundred watts for a few hours, so you would have to work pretty hard just to run the computer you're reading this on, see;
http://www.ent.ohiou.edu/~et181/hpv/hpv.html
If you're Lance, you can increase that a few times. For survival/eco-friendly power, wind, solar and hydro may be a better choice:
http://www.otherpower.com/

As far as converting a bike into a moped, i've seen products that do this, but only gets speeds up to 30 mph. Besides, i've taken spills on my bike at 20 mph while commuting and that's no fun, can't imagine doing it at 30+ mph.

The computer I'm using pulls a max of 45watts, thats with the cdrom and a usb device plugged in (small laptop, everything is external)

Why not add an electric motor to your bike, pedal could move the bike and charge the battery then when you need help going up a hill or getting high speed the motor could pull from the battery.

It appears that with electrics the problems that occur because of the low energy density of batteries are low performance and weight. Most i have seen have a range of 20 miles or so while moving the bike at 15-20 mph (unassisted). But this comes at the price of a bike weighing 50-80 pounds. And they're expensive. Still, it might be useful for those not in the best of shape and/or have a evil hill on their commute. Some links i found on treehugger:
http://www.50cycles.com/torq_spec.shtml
http://www.aprilia.com.au/bicycles/enjoybicycles.html
http://www.greenspeed.us/machine-x_zvo-bike.htm
http://www.avantibikes.com/index.php?opt...p;amp;Itemid=24

My father-in-law set up a pump for the cottage water tank that ran on bicycle power. Took 10-15 minutes of pedalling to fill the tank with water from the adjacent lake. The system was used for toilet water only.

Your knees really shouldn't hurt after riding, is your leg straight when the pedal is at the bottom?

Oh ok. I once had this weird pain in the back of my knee and since i use clipless i thought it had to do with pulling up too hard while pedalling or that the seat was up too high. Took the seat down a cm or two, but it appears that it has more to do with the fact that while at a light, i put my right foot on the curb and then push off with it.

Thats weird, what's in the air that is eating your rubber? In LA, the ozone in the smog will eventually make rubber rot.

Izzy, here's my take on your bicycle issues.

Your knees really shouldn't hurt after a ride, even if you aren't in great shape, unless-

1. Your bike does not fit properly, which is not merely a matter of frame height. There are many different factors. Even a change in crank length or a different stem can change a things a lot.
2. You are riding on very rough and jarring surfaces.
3. There is something wrong with your knee(s), either an injury or something you were born with.

If you are going through bikes so quickly, and are uncomfortable after 12 miles (which really isn't all that far), then spending the moeny for a better bike (i.e. not a department store bike) is probably what you need to do. I'm not talking about a top end bike, just something from a better company and sold in a store where they can help you with the fit. Many department store bikes aren't even put together correctly. A decent bike will be lighter, stronger, and repairable.

Make sure you tell the bike store people any issues you have had with your old bike too (i.e. knee pain). Tell them what type of riding you are most likely to do also. If they don't want to listen to this, and don't help you with the fit beyond frame size, turn around and walk out the door. Not all LBS (local bike shop) are created equal. A good shop will even change stem size or angle for free, as long as the new stem isn't a lot more expensive.

You may be able to find a used bike that fits you well too, but that is a bit more of a gamble. If you have the time keep checking any LBS that carries used bikes until the right one comes along. Right about the time that new bike models come out is the best time to look due to all the trade ins. Just like wtih cars, a used bike can be a lot better value as long as you are buying it from a reputable store that checks them before sellign and offers some sort of a limited time warranty.

I'm not surprised the garage is rotting the rubber on your bike or causing rust. I've heard of that happening to other people, sometimes at an alarming rate. I've never had any problems though, so I'm not sure what the diffeence is.

Izy,

I second everything Paul wrote. Extending: Department store bikes are of questionable value for adults. Short recreational rides on pavement, fine. The reliability, durability, maintainability, and relative ease of use of a decent bike is such a sharp contrast you'll have to experience it to really appreciate it.

IMHO, the sweet spot for value is in the $600 - $1,200 range, more or less. Depends on shop, make, and if you're buying current year version or last year's version - and how well you negotiate. Within a frame family, the price differences are mostly on (replaceable) components. So you could get in cheap with the low end of a frame family and put better components on if and when you trash something - although even the cheap end of a good bike is almost always much better than anything on a department store bike.

Save up - plenty of last year's models are available right now.

Tom