1) Anyway, the hitch came with three spacers, and one thin sleeve. Since one sleeve fits in the end of the hitch and over the seat post, that's were I put it. Then there are two bolts that clamp this assembly down. The problem is that if you tighten it, it can't pivot on the seat post. If you leave it a bit loose, it won't stay were I want it vertically on the seat post, but drops to the bottom and is a tad sloppy.
2) I was curious if the one very thin sleeve was supposed to go inside the other plastic sleeve, but it doesn't fit well.
3) The other pivot point that lets the bike move up and down just has a quick release for a bolt. But this fitting has the same issue, if you tighten it up, it can't move. You leave it loose it's sloppy.
I wanted the burley, and this hitch seems so poorly designed, I may take it back.
Anyway, Am I doing something wrong? Is this really designed by Trek? Should I return it?
Here is something from the "recreational & family" threads where you'll find much info on trailer bikes.
---- I bought a Trek Mt. Train 241 last Saturday, during the LBS's "Spring Sale". The shop was swarming with people snapping up "bargains". The folks running the shop were swamped. They could not locate the owner's manual for the 241, and the available "tech" who attached the 241 to my bike appeared to be about 14 years old.
Out on the road, the 241 had a side to side wobble that scared the heck out of my eight year old nephew until he began to "balance" his half of the "tandem" independently of my half. I suspected the LBS had failed to attached the 241 correctly, and I returned to the store to suggest they put a rubber shim between the seat post and the plastic insert that sits inside the metal clamp. The LBS thought a shim would prevent the "trailer" from pivoting properly and said the wobble was "part of the design".
Anyway, on Sunday, I sent an e-mail to Trek. At 10 a.m. Monday, I got a helpful reply. THAT high level of customer support is why I prefer Trek products over most brands. Two hours into a new business week, they sent exactly the information I needed.
Trek said the plastic insert must fit tightly to the seatpost, using rubber shims, to eliminate wobble, and to enable the metal mount to pivot smoothly around the insert. Trek also said "extra" mounting heads are available as Part 71584, to quickly switch the trailer between bikes.
With proper installation, the Mt. Train 241 (with 24 inch wheels) will suit kids with a good sense of balance between about age six and age ten who weigh less than 80 pounds. Both the seat and handlebars have a wide range of adjustments to "dial" in a good fit. The short crank is much more comfortable for pedaling for eight year old legs than the longer cranks used on many kid's bikes.
Although the weight limit is rated at 80 pounds, you could probably pull about 90 pounds or a 100 pounds IF the lead bike has a beefy steel seatpost, not a light alloy seatpost. The fact that the weight of the trailer is on the seatpost is the weakest point of this design. Placing the clamp right where the seatpost enters the seat tube reduces the stress, but it still might be more stress than "ultra-light" allow seatposts can handle.
I will probably "upgrade" the nuts and bolts on the mounting head as well. Inspecting the mounting system before each ride, and every couple of hours during day-long rides is advisable, to keep everything adjusted tightly.
The "set-up" hassles are well worth the end result: a way for an adult and kid to enjoy long rides together, at the same speed...something that is difficult to achieve when an adult is on a road bike, and the kid is riding a kid's bike. And, it is nice to know EXACTLY where the kid is located when you hear a truck or car approaching from behind you. -----
the hitch will go to the bottom of the seatpost, that's where it goes. I have mine on a piece of PVC pipe to hold it up so the bike clears my rear rack.
On my bike I have it pretty tight around the seatpost, the weight of the unit will get it moving. I also keep the quick release half of the hitch tight and lube it every now and then.