Front derailleur-How to DIY your bike with good carbon frame

Front derailleur

This is becoming irrelevant on modern mountain bikes and some gravel bikes, but it’s still important for road bikes.

Braze-on front derailleur: This is a direct-mount option that doesn’t clamp the seat tube. Frames with a braze-on have a tab sticking out from the seattube to mount the derailleur. 

Seat tube clamp front derailleur: You’ll need a derailleur clamp that matches your frame’s seat tube diameter. The dimensions can be found online but it's also very easy to measure your seat tube with calipers. Common sizes are 28.6mm, 31.8mm, and 34.9mm.