Having had a recent wake up call that I'm not immortal(!), I need to make a will. I'd like to leave a bequest to organisation(s) that support road racing, and/or road racers. The obvious one is the Rob Vine fund. The TT Marshalls association don't accept donations, and the Simon Andrews Fund is now closed. So are there any others that can accept donations? Thanks in advance.

A good idea! 
never thought of that myself,
maybe the Southern 100 supporters club? https://www.facebook.com/S100SupportersC...cale=en_GB
Friends of the TT riders association https://ttra.co.uk/fottra-index.htm
The Dan Kneen Charitable fund https://torq.im/
some that may fit the bill 
& Joey Dunlop Foundation, of course! https://www.joeydunlopfoundation.com/

hope that helps.
maybe I'll look into it too!

Thanks Captain. All good suggestions. I've been in touch with FoTTRA, and they have a new web site - https://fottra.co.uk/
I was over on the year we lost Dan Kneen, and I like that they cover mental health and emotional support as well, so they're on my list.
It should only require adding a few lines to a will, to include a bequest so I'd urge everyone to consider it. Or you could even do it less formally, and leave a 'letter of intent' with your will.
The only tricky bit is to leave enough details for your executors, who may not be road racing savvy, to identify the organsiation/charity, in what could be many years into the future.
Thanks again.