The mechanic’s report by Kare:
I hauled our trailer to Lohja and back with my old, trusty and rusty Surly Cross-Check. It is a great bike and we have had a lot of fun together, but it did not feel rigid when stomping on the pedals uphill with trailer. On gravel road downhills I also had some dangerous moments when I turned the handlebar and the frame responded just by twisting.
This morning I loaded the trailer again and tested it with different bikes.
My steel road bike SAB is made of Dedacciai’s triple butted high-end steel. With fully loaded trailer It was scary, wobbling all over the road.
My gravel bike Cross-Check is made of basic double-butted CroMo-steel. It was ok but not good.
My cyclocross race bike On-One Pickenflick is made of oversized, unbutted titanium. It has got oversized carbon fork. With trailer it felt rigid. Especially the front end was stiff. Rear end was quite ok.
Pickenflick also has disc brakes and a simple 1 x 10 drivetrain. That means safety and durability. I suppose I will have to swap the cross rubber to touring tires and show Pickenflick some folk music festivals this summer. Steel is real, but oversized titanium is stiff.
Emilia does not have this kind of problems. Pelago Sibbo is one sturdy little bike, and carries fully loaded panniers with ease.