One of our riders reports this a migraine. It once struck during a ride and he had to wait for the visual disturbance to go as he could not see well enough to avoid hazards. He swears by Solpadiene as a painkiller.

How about just making sure you're well fed and hydrated before and during the ride? Sounds crazy, it might just work.

I used to ride with someone who would get this regularly. I seem to remember the post ride recovery drinks helped.

Why not make an appointment with your GP.

I'm not convinced that it is dehydration/food etc. [for me anyway]

I don't suffer with it after long runs just on the bike, if anything – I take less water when running

stuartanicholson thanks for the shout about My protein thats saved me buying about 3 tubs of crap of CRC to make up my own drink. 🙂

Yep no problem. You can also use a protein/maltodextrin/l glutamine mix as a recovery drink too…its well cheap!

pain in the arse is,nt it. i get them even when well hydrated.
i put mine down stress when riding like mean it and masive concentration.
3 anadin exra after usualy does the trick 😉