What Bike Parts Can Be Made From Alumnium Castings?

kids bicycle seat parts image

himynameis

i know lugs can be made...
what are the other possibilities?
seat post collars? stems? dropouts?

Answer
Yes, lugs can be investment cast but they are usually steel, not aluminum.

Contrary to the other answers, MANY parts are die cast and are generally labeled as 'melt forged'. This is something the marketing people came up with to reduce the dubious reference to die casting. If you were to go to a U.S. factory they would tell you until they are blue in the face that die casting and melt forging are different things, but in the bicycle industry they are considered identical.

Commonly die cast bicycle parts in aluminum include dropouts, bottom brackets, stem and seat post heads, suspension fork crowns, chainstay reinforcements, brake levers and calipers, derailleur bodies, and accessory bosses like cable guides. Also, blanks are cast for head tubes, seat post collars, and other items.

In the past, there was a company called Trusty (later purchased by Yamaha) that made a cast aluminum fork for their road bike. The fork started failing- not because of the cast part, but because of the way the casting was attached to the steerer tube- and earned the name the "Death Fork" (although nobody actually died to my knowledge).

Huffy also had a kids bike called the Metaloid http://bmxmuseum.com/bikes/huffy/31318, the frame was cast aluminum and looked like a piece of a steel bridge girder. Pretty cool. Kent currently markets a cast magnesium folding bicycle http://www.amazon.com/Kent-Ultra-Magnesium-Compact-Folding/dp/B000H6G146 , but I suspect it is aluminum alloy with an added dollop of magnesium to the mix.

Will change in sitting position affect the speed of riding the bicycle, What practical canbe done to prove it?

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I have done a survey and over 80% responded yes to the above question. In order to prove it, I need to use physics to prove it.

I just want to know if you have any safe and suitable ideas which can allow students of the class to experiment this. I need to know the design of the experiment, variables, procedure and how and what will the graphs be?

Thanking You

Answer
You would have to look at the angle of the legs in relation to the pedals to get an idea of the actual force exerted. If the leg is exactly at right angles to the crank of the pedal for most of the time, there will be the greatest force and so be more efficient.
Constructing a model of a person seated on the bike would be the easiest way to demonstrate this and measure the angles etc. with different seat heights and sizes of frame , handlebars etc.
Flat models could easily be made from thick card with the moving parts fastened with paper clips . Kids could be given a photocopied template to trace onto card and then make the model themselves. Different positions, sizes could easily be found and then the project could then continue using protractors to measure angles .
You could make one for yourself out of clear perspex and put in on an overhead projector so that the whole class can see what variables you are going to measure
Graphs of two variables could be drawn - e.g. height of seat v angle of leg. with the optimium being at the 90 angle.
Should make an interesting project and keep them busy for a few lessons.
Good luck and have fun .

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