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I'm on my third second-hand cargo bike trailer, and my third bicycle, in three years, but still on my first Burley Classic Connector. Axles have broken; aluminum tubes have sheared, steel tubes have ripped; welds have broken; parts have been un-gettable. The twp parts which have outlasted everything else, were the ones supposed to break first -- the Classic Connector with it's Flexible Connector to the trailer arm, from my first Burley trailer, a 1990 Burley Roo. Both parts were original to the 20-year-old trailer when I got it in 2010. For one reason or another, I've used that same 1990 connectors on each subsequent trailer. I expect to soon ditch my current rusty steel Winchester trailer , for a slightly newer, less rusty Winchester -- which doesn't have a hitch connector, so I'll be using the 23-year-old connectors again.

When I got the Burley Roo trailer in May 2010; people with bike trailer experience warned me that the connectors would be the first thing to break. I bought a replacement Classic Connector, at a local bike store for $35 CAN, and wangled a free replacement "lolipop" Flexible Connector -- the rubberoid thing that joins the connector to the hitch arm, and provides the unlimited flexible joint required between the bike and the trailer. That was three years ago, and I haven't had to replace either part, but I'm not complaining.



The Flexible Connector is every bit as important as the Classic Connector it attaches to. It looks a little rude by itself, but that's understandable, given how obscenely well it works.

You have to have the right connections

A two-wheeled bicycle trailer connects to a bicycle, by a hitch arm, in one of three ways, that I know of:

1. To the seat post


2. To the inside of the triangle the frame forms by the back wheel drop-outs


3. To the back wheel axle

The first method raises the overall center-of-gravity of the load you are pulling, and feels weird, and jerky to me. What little I've found on the physics of bicycle trailers emphasizes that the hitch point should be as low as possible, and if the load itself can at all be below the axle, better still. The last method is necessary for disk brake-equipped bicycles. I've read that it puts a real strain on that poor little axle. I don't have disk brakes. The Burley Classic Connector uses the second method.



This diagram gives a good idea how the Burley Classic Connector attaches to the frame, and how the Classic Connector atatches to the trailer hitch arm, or "tongue," via the Flexible Connector -- from Burley's Hitch Manual, page 11.

Bowed but never broken

The kind of forces at play where a trailer hitch connects to a bike frame are going to be prodigious -- I've seen derailleurs twisted like taffy, wheel rims peeled like bananas; chain links tear, and all that stuff is made of steel. A Burley Classic Connector is made of .... something -- fiberglass, some kind of plastic, but not metal, and the Flexible Connector? Wow. I can't bend it with my bare hands but look at this photo of bicycle laid down on it's side, with the trailer connected:



I've tinted the flexible connector green -- look at that deformation! It's designed to do that, and it's been doing it for 23 years, in blazing hot, and freezing cold. This solid Flexible Connector is completely superior to Burley's older, spring-based, flexible joint.

Two years ago, an elderly driver slowly backed into my trailer at a bottle depot. His car pushed the trailer and bike back into a wall. The plastic box on the trailer cracked, but the Classic Connector, which is cleverly designed to never come off when pulled, just gently disengaged itself from the bike frame when it was pushed hard enough.

People in bike trailer forums talk about the newer skewer axle mounts as being "more modern," and more "user friendly," maybe. Some newer bike frames will require that kind of mount, but I don't think it could possibly work better, because, in my experience, the Burley Classic Connector has worked perfectly.