I had to come up with a way to stop the U-bolts from crushing the seat post.
What I did was use some putty to make a support around the back half of the seat post.
First I sanded off all the paint on the back of the thick steel plate, and then I drilled some shallow holes to "Dimple" the plate, this will give the putty something to hold on to.
Sorry for the lousy pic, I was in a bit of a hurry.
I then put the old seat post in place, the non-oval section that was in the bike frame (I did check it too, it was still round!) I first wrapped the seat post with some clear wrap stuff, in retrospect I should have just waxed the seat post, that would have worked better.
I used this putty, it is a two part stuff, comes in a stick, the outside and inside of the stick of putty need to me melded together, then you have about 5 minutes to work with it until it gets rock hard. The putty stuff is very good, I've used it on motorcycles before, when something broke, I've drilled and tapped this stuff and it has held up for many years.
I melded the putty, and then I put a blob of it on the back of the hitch, I put the seat post in place, and tightened (lightly!!) the U-bolts, I then pushed the putty into the shape I wanted, making sure it got pushed down into the dimples on the steel. After about 5 minutes when the putty was hard, but not rock hard, I removed the U-bolts and did some adjusting. Once the putty is set and cured, it is almost like steel, thus working it a bit when it is still somewhat soft, has it's advantages.
I removed the old seat post and then I put some #240 grit sandpaper on on it and sanded the inside of the putty a bit to make it smooth and to enlarge it just a touch. I let that set a side and harden for about an hour, then I put a thin piece of rubber around the seat post.
(you can see the hitch with the putty on it sitting on the rack of the bike, the pic makes the curve in the putty look oval for some reason, but I assure you, it is round)
I am hoping that this will take up any slack in the hitch to seat post connection and might even provide a bit of a damper to the clackity clack of the connection between the hitch and the trailer.
I mounted the hitch, and I carefully tightened the U-bolts. I do not own a torque wrench that goes down to a very low number (on my Christmas list!) so I was careful and consistently tightened them down in a crisscross pattern. When I had it tight enough that nothing moved, I turned each nut an extra 1/4 turn. To make sure I was not crushing this new seat post, I checked the post above and below the U-bolts, front to back, and side to side, with my vernier caliper. It measures 27.2 front to back and side to side, so it is still round.
The old seat post, in the area that it was clamped, now just sitting on the bench is certainly NOT round, it is 27.8 side to side and only 26.4 back to front, so I certainly squished it.
Here is how it looks now.....
Time will tell if this holds up, or if I have to go something else.
I also bought new wheels
The Shimano WH-M505 wheel set....
I know, budget wheels, but they are strong and should last a while, that is what is important to me. I haul around a trailer full of beer for deliveries and I still weigh 266 pounds, so I'm not what you would call "Concerned" about the wheels being a bit heavy.
This is the fourth set of wheels I've had for this bike, let's see, 22 years and three sets of wheels, that is over 7 years a set, not bad I guess. To be fair, the first set only lasted about a year (cheap, and I did lots of off-road riding at that time) I paid about $177 USD for the set, including tax, I think I got a good price.
Now I just have to wait for the spacer for my 7-speed cassette to come in, the wheel is designed for 8 to 9-speed cassettes, but I'm told with a spacer the seven speed cassette I have will work fine. I sure hope so, because the shifters I have are also 7-speed, I really don't need or want to upgrade to an 8 or 9-speed cassette and also have to buy new shifters, no thanks.
This bike will continue to see daily use as a workhorse, one day, down the road, when I get down to say 185 lbs, I will most likely celebrate and buy my self a new bike, but the old Cannodale will keep on being used.
Cheers!