On Thursday, August 9, 2012 7:52:51 AM UTC-5, stryped wrote:
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!

Very interesting. Again, I am not as experienced as you guys as to metalworkig here. I have the equipment but have never brazed. I have miged, however heard mig is not good for 4130. (NHRA does not allow it). I have read on brazing and it sounded simple enough, get the temp to a certain point and melt the brazing material into it. Capilary action would fill the joint.

I have toyed with the idea of buying a cheap harbor freight tig. However, I know some of you would frown on harbor freight stuff.

You are right, the weight concerns me and most of the bikes are carbon fiber. I have toyed with the idea of carbon, but have no experince with it and not sure how to ensure it would be safe enough when complete to average 20-30 mph.

The only advantage to steel, as I have read, is I have heard it is more "comfortable" for lack of a better term longer distances, something about absorbing road bumps. This would be benificial in a long triathlon in terms of saving your legs for the run.

But I agree, lighter is better.

Again, I am new to all this so forgive my ignorance but the lugged frame set up looks like you would just stick the tubes into the lugs, that the tubes would not have to be mitered. Is this true? (Kind of like thise strong tier kits you can buy to build a table ot whatever without having to cut miters).

I have no jig and would have to rely on a table or system of 2x4's. Some kind person on here mentioned somethign that I had read but forgot about, pinning. Seems the old timers if I understand it correctly would drill the lugs and tube and insert "nails" to hold the assemply togther before brazing. WOuld this negate the need for a jig?

I am just mentally trying to grasp all these concepts.

Thanks,

Don.