Human Powered Vehicle Help!

[YoungEngineer01]

I'm working on a Human Powered Vehicle at school with a group of stubborn boys who won't admit it but we need professional help. We have a bike we call the Rust Bucket, and it is a pile of c***. It is all rusty, the tyres are getting worn out fast, the chain is old, the welding and brazing done on this bike is c*** and now they are trying to reinforce bits of the bike with bits of chrome moly and a crappy welding job. It's got great steering and is quite fast, but it is very weak and falls apart (wheels come off, chain breaks, the joints are c***). The people who are currently trying to fix it are trying to weld it but they honestly have no idea what they are doing, so they are trying to make the bike stronger in some places with crappy and weak welding. The way they are currently welding is heat up the metal and wack it with a hammer a couple of times then just try to braze around the joint. We know welding and brazing are to different processes, they want to weld the joint together but that has continued to fail and then when it is all messed up and you have a piece o c*** bit of bent metal that they can't weld because they can't heat it up to a high enough temperature then they just give up and braze it. Them trying to do this is also eating through our money because the are using so much oxygen up with the brazing tool and each week or so we have to buy one or two new bottles, so far we have gone through 5 or 6. As for the wheel I have no idea why they fall off, and we also suck a removing and changing the wheels. Last time we tried to change the back wheel from a 16 inch to a 14 inch, we couldn't figure out how to reassemble the gears on the wheel and then cassette got busted and that ended up being $140 for a wheel change and getting a cassette remover and a chain whip. They are spending so much time on the frame they haven't even thought about the body/shell.
. We need ideas to save this bike that are cheap and effective. Our teacher is throwing such a big project at us in the first year of Engineering that even she didn't understand that this was going to be a hard and costly task. All we have is a bike frame of rusty chrome moly with no corflute shell on yet. Any suggestions are welcome, a picture of the bike can be found at http://s1370.photobucket.com/user/coola ... ent&page=1" onclick="window.open(this.href);return false; and more photos will hopefully be uploaded tomorrow. Please be aware that I am not the smartest person so please make the responses and suggestions simple. Thanks a lot!

[Aushiker]

The link to your photo needs sorting for starters ...

Andrew

[YoungEngineer01]

The link should work now

[bychosis]

For bike maintenance start at Sheldonbrown.com . Great starting point for working out how bikes are built and what keeps them ticking.

[Recycler]

My first sugestion would be to get a St Christifor Medal and fit to the trike. Have you worked out the gearing with that chain ring ? Why not use smaller steel tubing on the body, and use a small inverter stick welder ? What type of steering have you fitted ? These are few issues i can see. I am keen to watch your progress. Good Luck ! Bob

[Roinik]

Firstly, where are you, it looks like a TAFE somewhere.
Do you have plans for this contraption?
A few pointers. Your harness doesn't comply with regs. Your chain is too long. You can't form a strong butt or fillet weld with brazing, you need to source some old brazed bike frames to get some lugs to make it stronger. Either that or you can try to source lugs elsewhere. Definitely check out a welder and the correct rods for Cr-Mo tubing. After blowing a few holes in the tubes you'll soon work out the correct amp setting.

To me it looks like most of the failures of the tube are in the heat effected zone. Sweat brazing doesn't require loads of heat and should be ok if lugged.

As for the wheels, I can't really see.