"anorton" wrote in message
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"Existential Angst" wrote in message
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"stryped" wrote in message
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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.
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EA



It think if I were going to build a frame without proper tools and
fixturing, I would look at making a carbon fiber frame. Working with
carbon fiber is a lot like fiber glass. It is a lot of time and tedious
craftsmanship, but it seems very do-able at home. There are several people
on the web describing how they made theirs. Here is one:
http://theprojectjunkie.com/composit...e-project.html

Besides, your first homemade aluminum frame is probably going to look
second rate, but even a ratty-looking carbon fiber frame will be cool.

Indeed.
How much do you think carbon fiber tubing would cost for a bike? I imagine
the weight would come in around 5# or under.
--
EA