Old Cannondale Bugger "wobbles" while riding.
 

Hey guys. A while ago I picked up a cannondale bugger trailer for $20. Seemed like a good deal. I really only use it for grocery shopping, but I'd like it to be more... stable while doing so.

http://glennview.com/jpgs/sports/bugger/nos/big_4.jpg

Basically the trailer connects to the seatpost and has two wheels. I noticed that the trailer wobbled (literally pulling my bike back and forth) when I first got it. The trailer itself moves back and forth on the road, pulling my bike with it. Someone riding behind me was "scared for their life" with how much it wobbled.

So I replaced the press-fit bearings with new ones. That was fine. It didn't help the wobbling much though. The trailer has a very long through axle that goes through both wheels with nuts on the outside.

So I trued the wheels. They were pretty out of true so I thought this would help. It helped a bit, but the trailer still wobbles and pulls the bike back and forth when weighted. The wheels are within a mm of true, so that's not the issue anymore.

Has anyone had any experience with these trailers? Am I just loading it wrong? The wheels don't FEEL loose when I try to push them back and forth. Does how I attach it to the seatpost matter? I've used a bolt which holds it in very tightly, and a rope which holds it more loosely.

Any ideas? In the end I really don't care as I have <$30 into this trailer, but still, I'd like to make it work as it's a cool old bike trailer that's in decent shape.

EDIT: Obviously the wobbles are more apparent at speed. At slow speeds it's hardly noticeable, but once I get up to cruising speed (maybe 12-14 MPH with the heavy trailer) it wobbles like crazy.

EDIT2: Looks like my bugger doesn't have the original hitch that came with it, instead it has a hard plastic thing that slips into a slot on the end of the trailer. The hard plastic is then forked so that it'll fit around the seatpost, then you can put a bolt or rope through two eyelets in the top of the fork. I, unfortunately, don't have pictures here at work.

I had one of those back in the late 80's, they did have a tendency to wander when empty, with some weight low in them, less so. I don't recall exactly what the hitch looked like, but I do recall it had to be snug on the seat post and for some reason I seem to recall having to wrap a scrap of inner tube around the seat post on one of my bikes. I pulled with a Motobecane Nomade (sport touring bike) and a Giant Iguana MTB. 10-12 mph was as fast I would go with it.

Aaron :)