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 :
![](https://r12evn7z.cdn.imgeng.in/wp-content/uploads/2019/05/2019-05-18-14.58.07-1024x768.jpg)
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 🙂