To all: I built this frame in 2010 and it is still holding up fine. See thread
here for more details. All done using a standard Lincoln MIG welder with Argon shielding gas. Pulse welds only, and I only burned a couple minor holes, easy to patch. This frame has withstood a fair amount of abuse (3-4 foot drops, curb hopping, stairs, etc) with no signs of fatigue stress (welds or tubes). Just FYI.
Rider Weight: 155 lbs
Frame Material: 4130 Aircraft Cro-Moly from Aircraft Spruce (very very highly recommend dealing with these guys)
1.5 x 0.049" Tubing
90 ksi Yield Strength
Safety Factor (worst case loading): 3.0
