"stryped" wrote in message
...
I dabble in metalworking for fun. I also run marathons and some triathlons.
Been thinking it would be neat to be able to say I built a bike and used it
in the triathlon. I have a road bike but not a triathlon bike.

As far as frame, I am limited becasue I dont have a tig welder. I do
however have a mig, oxy torch/weld set and arc welder.

I am guessing my choices are aluminum tubing or chrome moly steel.

I can mig weld the tubing with argon and aluminum wire but not sure if
this is ideal. I have read you can braze it.

I have read conflicting advice as to whehter it is recommended to mig 4130
or not. (The same for brazing it).

Weight is an issue. I want it to be light but at the same time be strong
enough to do a half or full ironman. 56 miles/112 miles.

I appreciate it!

sci.engr.joining.welding would be the better ng for this.

As far as projects go, my understanding is that unless you will be hacking
together black plumbing pipe and couplings, a bicycle frame is probably one
of THE most difficult welding projects to tackle -- a deceptively difficult
project all the way around, incl. fixturing.

The custom shop I visited used very high end dedicated tig, one brand being
Thermal Dynamics, and one other, something-arc (not lincoln or miller).
Fishmouthed thinwall tubing joints are not the easiest welds, a lot of
machine control is required. He showed me an innocuous small bundle of
tubing for his next build, a ridiculous price tag for a few feet of tubing,
iirc on the order of $500. Whatever it was made me gag.

Custom frames (the frame alone) start at $3K, and go up to $10K, mebbe more.
I assume there is good reason for this, but I'll spend only $19.99 on
running shoes, so I'm not exactly on the same wavelength as this crowd.
I know they get the frame custom fitted for their body dimensions, a big
time consuming deal unto itself for pro's. I assume there is a rec.cycling
ng you could post to, to get some idea of their bike requirements.
--
EA