Looking for a flash bracket

I am looking out for a flash bracket to use with my gear.
It should fit to my Wimberley sidekick and to my 500mm and 100 - 400 mm lens.
I think, there are two possibilities: the RRS flash bracket or the Wimberley bracket.
As far as I know, both of them were mounted to the lens, not to the head of the tripod, true?
As I have never seen any of those brackets or used one of them I really would love to have good advice from my "BPN - Buddies" from overseas.
The brackets are hard to get here in Germany, so I think, I have to order one from the States?
I don't want to make a mistake, so please help me to make a good decision.... :)

Thanks alot to you!

Hi Rosl,

I would recommend the Wimb bracket since it is simple and light and I think it is more flexible. I even use mine in the past as a macro flash bracket.

Robert