There is a fair next week and they have a reverse bike riding contest, you know when the wheels turn the wrong way from the handles. Well, I’ve searched this site for info on how to make one, but I don’t know anything about bikes or what cogs are or anything. I just want to make one to practice before the fair so I can win a prize. Does anyone have any simple easy instructions on how to make a bike turn the wrong way? I don’t need it to be good,just so I can practice and ride a straight line. Please help. 
I don’t believe there is an easy way to build a reverse bike, I know Unicycle.co.uk sells them, but they are expensive. Probably the best way to learn to ride one is to ride your normal bike with your arms crossed, lay down some obsticles and weave through them, forcing yourself to think about which hand to use and how to turn.
Weld a bike in such a way that the front wheel is stuck in the straight position. If you can learn to ride it without any correctional steering then you might be able to ride the bike at the fair in the same way.
And it sure as heck wouldn’t hurt to learn to ride a normal bike no-handed.
Genius.
It is actually quite easy, though. Just cut out a spare headset from a junk bike [or make something that would replicate it] weld or otherwise fashion a way to attach it firmly to the original bike’s headset so it is right in front of it. Weld or otherwise attach a cog, or even half a cog [I don’t know where exactly to get one, either, but there has to be some ingenious item that you can use from Home Depot I find it has everything I need, if I ask the right people] to the handlebars. Attach the other [half] cog to the forks through the front [junk] headset so that the two cogs mesh. And that’s it. There are many pictures over here Reverse steering bicycle
Below is a picture of one Tommy Miller brought to NAUCC last year. The construction looks pretty simple, though the instructions above should be easier than machining that big block of metal. I’d stick with whole cogs/gears though, otherwise you’ll need to put “stops” on your handlebars so they don’t go too far.
Riding with your hands crossed, though it doens’t cost anything, isn’t going to do it. Your balance system and responses remain the same. It’s actually very easy. I tried the bike in the picture, but didn’t take the time to work it out. I imagine it could be done in an hour or less.
Also, a bike that can’t steer isn’t going to be very effective either. Even if you can ride it, you won’t be able to keep the reverse bike’s handlebars from moving. As soon as you think, you’ll steer the wrong way. This was my experience from learning a two-wheeled (stacked) unicycle. That took me about an hour total as well.
try riding the bike while it’s rolling backwards. you face towards the handlebars, but the bike rolls so the back wheel is in front.