Hi,
Although my Comet sports a beautiful solid stainless three piece bar made by Mac Read, I am concerned that any crash loading on its end will transmit the full impact to the sidecar fitting. For my Shadow I have made a more collapsible crashbar using a long piece of 16mm studding with a nylock one side of the sidecar fitting and a plain nut on the other. Each side of the stud is then hidden by a thin stainless steel tube secured by a stainless domed nut. The lengths are setup so that as the domed nuts pinch the tubes they also bind on the ends of the stud preventing them from easily loosening. I feel that this bar will offer adequate protection to the bike without transmitting so much impact to the sidecar lug. These bars are untested although I can attest to the value of the series D type D shaped bar fitted to propstand plates and top plates bolted to the sidecar lug. There were some made for the Indian badged Vincent which used four identical brackets to hold a D shaped bar which, while rare, would seem very desirable.
As an extra, I use my straight crashbars as additional workshop stands by using 4"x2" timber beams with a suitable hole at the appropriate height. You lean the bike and hang one timber on the crashbar. Then standing the bike up it is easy to lean it on that timber and push until the other timber can be fitted. The bike will then stand on these legs. If you strip the bike the whole front end, which is normally hard to store, can be stood on its front tyre and these timber legs.
Happy new year!
Cheers,