Can you fit a road front derailleur to the Anthem X?

The short answer is "no". It'd be "yes" if you could get a low mount road FD, but you can't. Road front derailleur's are either top mount or braze on. You can normally use a braze-on road FD with a bolt on adapter.

A top mount derailleur will not work on the Anthem X frames because where it needs to mount is no longer a "normal" type of seat tube. The seat tube is hydro-formed in a very organic sort of shape to provide the rocker pivot location for the top rocker plates. A top mount FD or bolt-on adapter will have to bolt around this, and it won't.

Here's a picture of the area where the top-mount road FD would have to mount to:

Here's a picture of a Dura Ace FD-7800 held roughly in place where it would need to go:

From the pictures you can see that the hydro-formed tubes provide a very unusual shape for a derailleur clamp to go around.

Are there any options?

Almost anything is possible if you're prepared to get your hands dirty! There are two options, but both involve some technical skills:

  • Option 1: form a carbon fibre clamp / band in place at the right position on the seat tube;
  • Option 2: make a bolt on clamp that mounts below the hydroforming on the seat tube starts and then has an extended attachment point that goes higher up than what you get on a regular braze-on adapter.

What about the FD being bottom pull?

Fitting a FD to most MTBs involves converting the FD from bottom pull to top pull using an adapter. A number of companies make such adapters - Speen probably makes the lightest. As an aside, some MTBs may have gear cable routing under the bottom bracket and then you don't need the adapter.

The detailed analysis

I put myself together a Dura-ace FD7800 front derailleur , Speen Umlenker and carbon cycles eXotic Carbon Front Derailleur Clamp, with a few aluminium bolts thrown in for good measure. Total weight 82g.

Dura ace front derailleur with speen umlenker and carboncycles clamp

Here are the problems:

  • hydroformed tube is too large - the seat tube increses in diameter as it approaches the rocker pivot, so a 34.9 FD clamp will not close-up properly. This makes for a very weak mounting, especially if you use a carbon clamp;

  • the seat tube has a different angle at the point where the derailleur clamp needs to go - this throws off the derailleur angle and makes the rear cage foul the tyre and rear triangle when in the granny gear;

  • the speen umlenker positions the cable attachment point far out to the side so the gear cable fouls/rubs on the inside of the driveside rocker plate.

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