Road front derailleurs

How to choose a road front derailleur

Choose a front derailleur based on three things: the number of speeds in the drivetrain, how it mounts to the frame and the difference in tooth count between the two chainrings. An 11-speed model will not work properly with 12-speed levers — the cable pull differs.

Braze-on or clamp-on

• Braze-on : the derailleur bolts onto a mount built into the frame. This is the most common setup on modern road frames.
• Clamp-on : the derailleur clamps directly onto the seat tube, in 28.6, 31.8 or 34.9 mm. Measure the tube; don’t guess.
• A clamp adapter allows a braze-on derailleur to be fitted to a frame without a mount, while shims let you adapt from one clamp diameter to another.

Mechanical or electronic

The versions Di2, AXS and EPS are most often ordered without battery : the battery is specific to the system and must be ordered separately. Check for ‘without battery’ before you buy — it’s the most commonly overlooked detail with this part.

The number of chainrings

• Double-chainring setups 2x10, 2x11 and 2x12 account for most of the road range.
• The 3x9 and 3x10 triple-chainring setups are still found on Sora and Tiagra, for touring and older frames.
• With a single chainring, there is no front derailleur: the narrow-wide chainring keeps the chain in place.

Chain catchers

A chain catcher — Stronglight, K-Edge — mounts in place of or alongside the derailleur to prevent the chain from falling towards the frame. Useful for time trials and single-chainring setups, where the front derailleur is gone but the chain can still come off.

To find out more: How to adjust your road bike’s front derailleur

See also: Road chainrings · Road brake and shift levers · Road cranksets and crank arms