Thanks, yes I had wondered about that route. IIRC the add on unit worked well but there was some question about overall frame rigidity and with the exception of occasional second hand sales the add on unit is no longer available. Thanks for raising that alternative though.
Thank you too to all those who have supported my thread. Your time and effort is appreciated.
No new to me cheaper ways to a cargo bike have emerged, but I had forgotten about Tandem conversion. In rough order of capital cost for shifting stuff we have:
1. Use your existing bike with a better rack.
2. Add a trailer to your existing bike - or, in my case, make better use of the trailer that you already have.
3. Buy an Elephant / Postie bike - eBay have some second hand deals too.
4. Buy a (second hand) Tandem and then turn it into a Long Tail - but there are questions about the multilevel load deck design.
5. Buy a (second hand) Long Tail.
I haven’t included make your own frame ‘cause only a small percentage of folk could successfully do that.
I haven’t included traditional Tricycles with one wheel at the front; I have some doubts about them and wouldn’t wish to unwittingly point anyone towards them.
I haven’t gone beyond a Long Tail ‘cause after them the prices can be a bit serious - even a second hand Long Tail is quite a lot of money.
Edit. I haven’t included Butcher / Grocer type bikes with large baskets at the front because they are rare and typically expensive for what utility they offer. Like the Postie bike they’re more courier than cargo, but the items can be bigger.
Edit. It occurs to me that good hub gears can be rather expensive and that the cheaper wide ratio ones of questionable mechanical efficiency and repairability, maybe it’s best to stick to wide ratio derailleur gears on inexpensive cargo bikes. The SA AW is good for shifting some weight and I’m a fan of them, but ultimately its limited ratio range compromises what it can offer the rider. Some of the older and entry level box bikes have three speed hubs (Shimano and maybe Sach) with back pedal brakes in them. The cargo bikes before them, the originals, had no brakes and fixed gear. Limited SA AW use aside on large cargo bikes its best to go the derailleur gears route - and don’t forget to change down early.
Edit. As I continue to look at the topic I increasingly notice the versatility of the Long tail type cargo bike and particularly so when the foot rails are also used as cargo platforms, the whole back of the bike is (subject to model variations) a substantial multi surface cargo rack built over a load carrying wheel - they’re certainly no less and might arguably be more capable of moving very heavy stuff than two and three wheel bakfiets and what doesn’t fit on a long tail (due to the item’s shape) can be carried on a trailer.
Edit. Whilst I hadn’t considered this in particular before it is worth while considering the weights of the different options as well as their costs. The cheaper options tend to weight less than the dearer ones. A Long tail does weigh more than an ordinary bike but they’re noticeably lighter than the two and three wheel box bikes (which are both more expensive and already somewhat heavy before you even start to think about adding a load into them).
A Postie bike might move me a little forward from where I am now, a converted Tandem could be better but I think that I might struggle to store it (Tandems typically ain’t small). There are no easy and (also) good answers, but a suitable Tug Bike and Large Trailer seems to work so I’ll stick with that for now and see what else turns up.
My thanks again to all who have supported this thread.
Don’t fret, it’s OK to: ride a simple old bike; ride slowly, walk, rest and admire the view; ride off-road; ride in your raincoat; ride by yourself; ride in the dark; and ride one hundred yards or one hundred miles. Your bike and your choices to suit you.