Hey guys, today I'll show you how I fit the new derailleur on an old frame by using a headset spacer
The clamp of the derailleur is 34.9mm and the seat tube of this frame is 28.6mm
To fill the gap, I use a 3/8 inch headset spacer because the dimensions of this headset spacer
Totally fulfilled the gap between the seat tube and the derailleur clamp
To insert it on the seat tube, you need to open it up
Cut out 3-5mm of it, I use a Dremel to cut it down
The spacer is very solid
So remove a thin layer on the other side would help to bend it up
Now put in some rubber to prevent scratching the frame when you install it
Align the spacer and put on the new derailleur