I have a question on the Wandertec bongo (large) size. Are these trailers strong enough to take off road. Will the hitch bar handle the stess off a rutted muddy fire road. Being the hitch is mounted to the frame (ie back wheel). Will this stress the frame of my mountain bike causing stress cracks on the bike frame.
The Wandertec BONGO bike cargo trailer frame can certainly handle the stresses of off road riding. We have not experienced issues for a bike frame being stressed due to this type of use, though we do not have thorough testing to support this.
More of the issue to consider is that a two wheel trailer is difficult to navigate on rough terrain. It does very nicely on dirt roads, however single-track or very rocky roads can be slow going especially with a heavy load.
Another thing to mention is that we are coming out with a new version of the Large Wandertec BONGO and introducing an XL version. Have a look at these posts about our prototyping of the new design that we expect to have available around June.