G'day,

get yourself a cheapo fridge trolley from Bunnings and with some basic mods can be 

attached to the seat tube like one of those Kiddy trailers.

Strap the Kayak on and off you go.

I did see one made this way on one of the Kayak Fishing forums, so it may be worth searching the net.

 Cheers

Maybe hacking up an old golf cart could do the trick :)

I was going to give it a go myself this week, chopping up an old bike frame and wheels. My main concern is that my bike brakes will need to be up to the job with all that added weight behind...

when at rotto and i think Emric1's idea would probably work best

one way to do it is to get 2 sets of bike forks with wheels, then make a frame using the basic cradle set up with old carpet on it , taking in mind you would only need about 3 feet of cradle and then have 1 length of tube running to the back of the bike and then bending the pipe up towards the underside of the seat where you just need a simple bracket and a d shackle to attatch . doing it this way you can make it to the length of the yak. all the stuff you need can be got at a scrap yard or recyclers.just remember you need to tie it down and i would suggest tying a flag on the back when transporting it and then locking it to your bike when it is unattended or it will go walkabouts 

Thanks guys I was hoping for an off the shelf solution I guess she will have to crack out the angle grinder and welder