Re: Can I use a Chromoly bike frame?
Minor welding like tacking the tensioner is okay, but as 2door stated, structural welds need to be done by an experienced welder, preferably with TIG since it requires far less total heat input and is much less likely to affect heat treating.
NHRA Drag racing rules require TIG to be used on any chromoly roll bar work.
I also agree with wheelbender about chromoly frames being harsher. The stiffness of the material transmits vibration more than mild steel and much more than aluminum.
Some people notice it, some don't. I love a stiff frame from my racing days but I must admit a buzzy engine might make them uncomfortable if you are sensitive enough to notice the difference.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.