I put a picture of my original frame. The internal diameter of the straight cylinder is 31mm.
In this frame was installed an original fork of diameter 1''.
I would like to buy this fork : https://www.bike-components.de/fr/Surly/Fourche-Rigide-Straggler-Disc-28-700c-p38261/
but the diameter is 1 1/8''.
I wonder, since there is some space between the frame and the 1'' fork, if I can installed this 1 1/8'' fork ?
I will need also to buy a new stem, but it's ok, my problem is more about the compatibility frame/fork.