Where is the trailer clamped? Seatpost, skewer, something different? When my son was young, I had a kid trailer attached to the seatpost on my Superlight and it would bob like crazy. I weigh 165, I put enough air for 250 lbs. and it helped. However I was concerned about wear and tear on the pivots more. Later I bought an inexpense hardtail frame from Pricepoint, built that up with old parts for towing the trailer.