Trailers are utterly brilliant, a properly designed one reduces energy expenditure by 80% - 80%!!
~But, the key here is to have the load over the axle. Both the Benpacker and the Carrix fail really as although they are good trailers to a point the weight is distributed between the wheels and the hips so one still carries half the weight on the hips, whereas a design such as the Radical Design Wheelie has the weight over the axle so there is almost no weight at all on the hips.
The one I made for Jenny (Spot, above) also has the weight over the axle and works perfectly, almost no weight on the body at all. Both can be loaded so that there is zero weight on the hips but this leads to a see-sawing effect so there has to be some weight, but minimal, a couple of ounces, and almost unnoticeable.
On Camino there is no place where a trailer can not be used, the axle width is not wide and never gets 'caught', and rolls easily over rocks and holes.
The downside to the Radical Design one is that it is expensive, well over £600! It is an extraordinarily well made piece of kit, engineered, and this accounts for the cost.
This company in France produce a trailer. (Jenny saw one on Camino this year). It is almost right! Most of the weight is over the axle but not quite. The draw poles are in three sections, for folding away, and what it needs is a bend in two of the poles that lead to the hips - this would lift the trailer up more vertically and the weight would then stay over the axle - this adaptation can be done at home by yourself or in any machine shop. They are one third of the price of the Radical Design Wheelie (about £200) and are a very good trailer indeed (well, would be if those bends were put in to the draw arms). As designed they suggest packing to allow 2kgs weight on the hipbelt .. but those simple bends in the drawbars would reduce that to almost nothing!
http://chariotderandonnee.com/article.php?mid=2&msid=0&menu_id=2&rid=1&lg=fr
I am thinking of buying one and improving it so the balance is right and then letting their designers know what I have done so that they can alter the design - but I may be wrong here as they specifically designed it for 2kgs on the hipbelt - don't get me wrong, this is a great trailer and for £200 is an absolute steal!
