Hi Stu,

I haven't experienced any swing or whiplash problems with the hitch and drawbar for my trailer: and the hitch is forward of the wheel centre as you can see in the photos.

I don't like the idea of the clamps on the seat tube, as the clamping forces could cause a future issue when wanting to adjust or remove the the seat post.

My stay mounted hitch seems to be perfect for me. It's a 6601 Aluminum frame on my hybrid, and although I have hauled 100kg (and over a couple of times) and more usually 30kg I have not experienced one problem.

On another tack: Trailer braking, I haven't progressed any further with my project due to tons of incoming orders. Mainly Pallet reclamation Bars, Camel saddles frames, Mule Pack frames and Elephant Howdahs, (and very little to do with bicycles). I mentioned balanced cable operated disc brakes utilising a spring return over-run type system. Similar in design and operation to car and van type trailers. Have you given it any thought?

Here is a link to a basic schematic of a cable and rod controlled system: http://www.kfz-tech.de/Engl/AuflBremse.htm