downtube thickness? (CroMo track frame)
i want to start modifying one of my track frames.
im just looking for some help for ordering my tubing for the project below
heres the scoop:
ive been cycling for maybe 2 years, and now that ive learned a little bit about frames and geometry i want to modify my beater fixed gear. i'm an engineering student, and ive been welding for about 4 years, so i know a little bit about structural integrity, ect
i want to cut out my downtube, then weld a new tube in that goes from about half way up the headtube to a few inches up the seat tube. then i will gusset the corners.
im doing this for a few reasons, 1.
i want to be able to do barspins, and 2.
because i like to work with metal and i take pride in my designs.
im a kid, i do tricks on a track bike. if you want to debate about it, please do it in a different thread.
heres my idea
-sorry the pictures are so crude, but they get the point across.
keep in mind i exaggerated the downtube position in the second picture to emphasize my idea. it wont be THAT high. only an inch or so higher
im not sure if the gussets are necessary, they wouldnt really add THAT much weight if i used 20g metal.
any advice/comments for keeping the frame stiff are appreciated
will i need to build a jig to hold the frame from warping once the downtube is out? or should it be alright? i plan on just using a demel tool, nothing crazy
my MAIN QUESTION with this is: what wall-thickness should i buy for my new downtube? i was thinking 1.25" OD
Last edited by GRHebard; 11-06-08 at 04:35 PM.