I have a solution. I found a Northern Dive 240L Large Bergen Dry Bag With MOLLE System it comfortably fits my 20 inch wheel Oxlane Decathlon folding bike. It has a dry suit zip, and a tube to control air. It has nice rucksack style straps. It has internal straps to keep the bike (or Military kit!) tight, and external compression straps. It also has lots of well made handles for manoeuvring it on to the dinghy or below.
So these are normally around £500, well it is basically a dry suit for a giant square sponge bob, but I got it on ebay for a lot less. I think I need some secondary padding so the sharper bits do not wear through.
I think I could now take an expensive bike on board like a Bickerton or a folding e-bike. The Oxlane is a "standard 20 inch folder, which means it does not really fold so small. (web site says it fits in a 76 by 44 by 66 cm box when folded). Having "float tested" another bike transfering to a pontoon (it failed the test) I bought this bike (Little Nellie) as it was cheep and I didn't expect it to last. It has a good range of gears with a grip shift and six speed derailleur. The short wheel base makes it hard to cycle up Cornish hills though. We also have a e plus electric bike which is about the same size and that is much better on hills as you dont have to try to stand up to pedal. I often use the bike to solve the problem of leaving the car in one port and going back by bike and train to pick it up.
