Current status of trailers
Biketour owns two Bob-trailers (there are some rumors [in the list and on this wiki] that the biketour had a kid's trailer as well, but at least since 2012 this has not been spotted)
After the [Biketour 2013] one trailer was left in Budapest, which has been picked up and is now with the coordinators in Thessaloniki. The other one stayed in Cluj with a collective of people that we spent most of our time in Rosia Montana and Cluj with. In April 2014 a Biketour 2013 participant picked it up with the aim of cycling towards Thessaloniki with it. Nothing was heard of him ever since, so that trailer possibly including some axles is for now lost in the dark.
During the [Biketour 2012] and 2013 we also had different 2 wheels trailers that were lent to the biketour for the summer and are now back in barcelona and Vienna. The one from Vienna called 'lollipop' could be borrowed again from the cargo bike collective http://www.lastenradkollektiv.at/fuhrpark-anhaenger/ we just need someone to pick it up and bring to the biketour.
There were some polemics about trailer design on the list (Feb/2012), this webpage points all the pro and cons of different trailer designs: http://www.carryfreedom.com/info.html
we have two trailers of the old version of Yak: http://www.bobgear.com/yak which have only one wheel and attach to the bicycle via the axle of the rear wheel. they can only be carried with quick release axles.
at the moment there is only one size of axle plus some washers to adjust when shorter axles are needed. there is a chance of some of the different size axles (without end bits) still to appear, since we are not sure whether they are with the traveling person or still in Cluj. people should be careful checking the length of axel they need, short can be dangerous, long can damage the axel, the bike and be very dangerous...
Two new standard quick release axles arrived (March/2012) at Research and Degrowth office. there is another new axle (taborda bought two for [biketour 2012] we ended up finding and repairing the old ones and just using one new) with taborda that is looking for a new owner (around 35 euros) - what happened to those, are there still some around, as you can read above at least one is currently lost.
On Biketour 2013 we borrowed a carry freedom Y-Frame trailer (big size) from a collective in Vienna and it served the biketour very well. It has two wheels and a simple platform on aluminium frame, thus it is very lightweight. There is also the chance to buy a second-hand small size of this type in Thessaloniki, for less than half its usual price. We might go with this, seeing as it is filling a need right now and would also be a very good addition long-term for Ecotopia Biketour.
Because it has two wheels this trailer has more stability, when you stop and your bike has a proper stand it can stand by itself while the Bob will most likely make your bicycle fall, so it needs to be leaned against a wall or tree etc. Also when riding this trailer gives better stability, it follows, you have to watch out for the two wheels when there are many potholes on the road but it will not make your bike as shaky as a one-wheeled trailer, whose stability depends entirely on your bicycle. This makes riding with this kind of trailer safer than the Bob.
An added advantage is its hub, which can fit both quick release axles as well as axles tightened with nuts, and is easy to mount. Thus several people which cannot carry the Bob trailer can transport the Carry Freedom Trailers with their bicycles.
Of course two wheels have more friction than one wheel and thus may make you slower. But the weight, the way of packing (how high, equally distributed the weight is etc.) will influence that just as much as the general design of the trailer.