Cheers U.P.O. its hilarious riding again. I'm not any good but who cares. The ramp I built is to the dimensions in the sketch up at the top of this thread and the transition is absolutely fine. If you build it like that with 11mm OSB sheet and 2x4 timbers its frame will wobble till you get the sheet screwed on and the deck built, but once done its solid as a rock.
Ive attached a few photos of the build. Obviously everybody does stuff a bit differently but this method has worked for me.
Somebody on this thread said - that at 8foot the ramp might be a bit too narrow. Its fine, but I tend to agree so as you can see from the last photo here its grown a bit since then!
Somebody also said about watching your knees because your bones might not be what they used to be. They are right! My knees are fine but lower back has been giving me a bit of pain! Im a bit older than you but skeleton not what it used to be, but again who cares!! Good luck with the build,,,,