I posted the other day about how a cheap bike trailer made for hauling kids had, at least for now, satisfied my cargo bike envy. A number of other commenters chimed in with their own experiences of using either shop-bought or DIY bike trailers.
With cargo bikes becoming increasingly popular everywhere, I would not be surprised to see bike trailers proliferating too. Given that they offer the advantage of hauling gear when you need to, and being left behind when you don't, they are a great option for those of us who only occasionally use bikes for heavier loads.
One project that appears to be combining both the flexibility of the trailer and the load carrying abilities of a dedicated cargo bike is Bristol Pedal Revolution's Bristol Cargo Bike Project. Described as an open source, up-cycled quality steel mountain bike frame that has been remanufactured to become "a light weight mega geared micro logistics vehicle of choice for a city of hills", it appears to include both a serious cargo carrier on the front and a heavy duty bike trailer at the rear. (From the looks of the photograph, electric assist is not part of the package at the moment.)
So far, this appears to be a beta model that's being exhibited to get feedback from the public. But we'll be keeping an eye for how the project develops.
As the water slide down Park Street has shown, my old hometown—Europe's Green Capital for 2015—is about as hilly as it gets. If cargo bikes can be made to work here, they can be made to work anywhere.