Tiagra rear derailleur is often mounted on gravel bikes but I did not like its limit to 34 maximum cog size. My hackers attitude comes out in these situations (and I don’t care breaking the component warranty) so I decided to modify the derailleur to hold larger cogs.

The problem is that the B-Screw is short and won’t allow you to increase the distanze between the lower cogs from the upper cassette. While some tutorial suggest to put a longer b-screw, I tried what can be seen below :

I used a chain pin and insert it to make the mechanical stop longer. Some thread blocker or resin to keep it still and you’re set.

It works 🙂