What changed when Odyssey introduced 41 Thermal? Aside from finally focusing on the quality of their components, and backing them up with easy customer service, they started to heat treat their welded components after welding.
The issue with welding
Although there is extra material when you weld two components together, the biggest detriment is the Heat Affected Zone (HAZ). The area immediately around the weld becomes stiffer and less ductile. These properties lead to more propensity to crack. Take a look at cracks, and you'll find many of them occur around welds (cracks in welds are always a manufacturing defect, usually arising from voids in the weld).
Gussets
This is a problem that has plagued bicycles since we switched from lugged and brazed frames to welded. Gussets are one attempt at fixing it. The idea is that welding a plate effectively moves the HAZ farther down the tube, reducing the likely hood to crack. However, this adds a thick plate, and welds to the structure, leaving us with a heavier component. And let's face it, gussets are just not an elegant solution (take a look at the cool design/gusset below. Reminds me of lugged steel road frames).
Internal Gussets
Internal gussets are NOT gussets. They are a type of offset butting. Although a good idea (because it places material where it can most effectively support the loads encountered), these do not move the HAZ. You may be able to argue the added thickness slightly shrinks the HAZ, it does not significantly affect it.
Heat Treated Tubing
Tube manufacturers, like True Temper, Sanko, etc, will heat treat their tubesets after extrusion to optimize their mechanical properties. However, this heat treating is altered in the HAZ. Farther down the tube, where the material is no heated significantly, the mechanical properties introduced by heat treating still stands. Does using heat treated tubes reduce cracking? Hesitently, yes, heat treated tubes MAY help to reduce cracking, but cannot make significant changes to the HAZ.
So what do we do?
Post Weld Heat Treating works to relieve the HAZ. The irregular shape of the weld remains, but the brittleness of the surrounding tubes can be significantly reduced. This simple step is often overlooked because it usually requires shipping the component off, or adding machines to the shop. But it is worth it. Take a look at Odyssey's post weld heat treating and how it has brought that company (along with a better business model) to great status in BMX.
So the next time you see a company bragging about 4Q Baked, 420 Baked, or these other marketing ploys (including 41 thermal, but they actually did it right), see if there is an alternative from a company telling you something meaningful: post weld heat treatment. Luckily, more an more frames are going this direction. We can only hope to see the same from Bars, cranks, forks, etc...
