help im trying to make a bmx frame

[shame]

Im so lost when it comes to the frame like im 5foot 7 inches and around 190 pounds so im debateing on the size and width of they aluminum frame can some one please help me this is a school project as well so i could really use somehelp if someone can help me

[welderShane]

What type of bmx do you plan on doing. If its racing, aluminum should be fine. If you do freestyle such as park,dirt,street you gonna want to use cromoly tubing. 5' 7'' your gonna want around a 20.5 to 20.75 top tube length.(Distance from center of head tube to the seat tube). How are your welding skills? Your gonna really need to tig it. Also you fitting and notching skills must be good. Let me know if you need anymore help. Im a fellow bmx rider so i know a alot about this stuff.

Shane

[Bikespot]

Currently i'm working on a Dj frame out of steel , mainly a prototype to see how well my design / welding and machine go together.

First thing you need to do is figure out the design , go to bmx sites. They will list all the geometry of the frame. That will give you a basic idea of what you need. I drew out my frame in autodesk inventor before i started anything.

Here is what i came up with , the only thing thats not complete on this drawing is the back axle plate.


As for aluminum its going to be a lot harder to weld than steel. Yes it will be lighter , but it all comes down to your welding skills. As for notching the tubing , the best way is with a mill and end mill. I'm using the mill and a boring bar. All you have to do is set the ram head to the right angle and cut.

There is alot to think of. Another i should mention is unless your a good machinist , you might want to find a place that sells pre made bottom brackets and head tubes.Once i get more done on my frame i'll post some pictures.

[exotherm]

Henry James is an excellent source for bottom bracket shells, rear drop outs, and proper double butted bicycle tubing. They've been a pleasure to deal with every time I've needed something.

http://www.henryjames.com/

[kcuts]

Originally Posted by shame

Im so lost when it comes to the frame like im 5foot 7 inches and around 190 pounds so im debateing on the size and width of they aluminum frame can some one please help me this is a school project as well so i could really use somehelp if someone can help me

Go to the following links:

http://www.frameforum.org/forum2/index.php?act=idx

they are really helpful. some of the World best Bicycle frame builders post and offer advise. Very friendly Alot of information

Bob