on the 1905 Mead/Whizzer (while en route to New York) first crack appeared in the down tube near ogalala nebraska. We stripped the bike down, took it to a local weld shop. it re-cracked just above this weld in grand Island, nebraska. Across the street from the hotel was a machine shop, so I bought a piece of angle iron, they machined holes for me. We went to the hardware store, purchased u-bolts with nylon loc-nuts and washers. I proceeded to bolt this 'brace' to the down tube and it carried me to the new york state line where the top tube broke under the gas tank mount so I coul;dn't see the stress cracks until it was too late; the down tube tore the head tube as the frame broke in half and the bike fell out from under me.
My first moto (a platform for many types of engine kits), has finally given up the ghost as the frame actually has "potato chip" warpage from many miles and hours of fun.
THIS is why I now gusset most of my motorized frames...
Rif