Dunwich Dynamo

Great pointers, thanks for that Steff

I've done it the past three years, so FWIW here's my advice:
...3) Make damn sure you're on a comfy bike - I did it the first time on a Dahon Helios SL ultra light folder with straight alloy forks and mangled the nerves in my hands. Not fun....

+1 on this point, there is nothing worse than doing a ride on a bike that you dont feel comfortable with. Make sure your saddle/stem height are adjusted for your body geometry. Make sure your tyres are properly inflated. Make sure you use the right bars i.e. just your average risers probably wont do, look for some drops maybe tri-bars (best option), and furethermore, make sure you choose the softest, comfiest saddle you have. You'll be amazed how uncomfy an average saddle can get after 20+ miles. Wear padded cycling wear so that you dont crush your manly area.