Here is a pic of how the Burley Piccolo links up. It attaches to a proprietary Burley rack. There is a threaded portion in the center of the rack, that the hitch screws in to. The big silver steel portion of the hitch is a backup to the bolt. The whole rig is wicked secure. I did a 7 or 8 mile ride with my daughter last weekend, and hardy noticed that my daughter was there. She has no sense of balance yet, so that's pretty cool. I even did a 3-mile ride with an empty piccolo, and there was no problem.

Overall, I'm blown away by the Piccolo. The downsides are:

1. No longer produced.
2. Hard to find, and generally demand a premium price.
3. Must use the proprietary rack
4. Heavier than other trailer bikes

The upsides are:

1. Wicked stable
2. Gear shifting on the Piccolo!!!!
3. bombproof
4. Accessories are still available from Burley.

I got lucky and found one on Craigslist for $50.00.