Is SLX FD 675-B front derailleur appropriate for my bike?

Question

It seems I've made a few 'tiny' errors when choosing components to upgrade my bike. The biggest issues I'm facing at the moment are crankset and front derailleur...

Bike is Eyble Psych 4 Black Edition (full suspension, 26" wheels) and I'm upgrading various (all) Shimano components to SLX. Because I'm not very familiar with all aspects of MTB geometry and compatibility of parts - I've put myself into weird position.

I've chosen M677 crankset (2x10, 22-36t) which (if I get things right) dictates position/hight of front derailleur (SLX 765-B, 2x10, clamp type). I've installed FD provisionally and found out that it sit quite low on seat tube (seat tube is with top pull cable routing). FD clamp is almost touching the joint of seat tube, downtube and chainstays (which are asymmetric) and it could interfere with movement of rear end of bike. (I didn't put chain yet and I tried to compress rear shock all the way - and I didn't notice that FD is hitting anything.)

Anyway, I'm worried if this setup is right and should I continue installing other parts? If this is horribly wrong - what are my options regarding another FD (please recommend proper FD type) or (preferably not) changing other components?

PS. I know I should have informed myself better before buying things :D

Answer 1

I wouldn't feel too bad about getting the wrong FD here. This is a very easy mistake when ordering a bunch of stuff for an unbuilt bike. Maybe there was a spec sheet available somewhere that advised against low clamp for your frame, or maybe not.

You shouldn't run that FD because, suspension clearance and any other issues aside, you've mounted it as low as it can go and there's still way too much vertical gap between the cage and teeth, shown in your first pic. That really shouldn't be more than the recommended 1-3mm. It will want to throw the chain, and the designed-in contact points with the chain and cage will likely be off. (Likely because the derailer does have some forgiveness there to accommodate the chain/FD angle changing based on what the suspension is doing, but starting with it way off is still likely to cause problems).

You also absolutely should not run it if it can contact the frame at any point in the suspension travel, or threatens to. When in doubt, test it definitively by fully deflating or unbolting the shock so you can freely check the rear end movement.

You need a high-clamp/bottom-swing FD, FD-M676 if you want to stay on-series.

Confusingly, once upon a time high-clamp/bottom-swing was the norm, and then low-clamp/top-swing came along to solve problems with suspension designs that were coming out, usually involving the seat tube not being there to clamp to. Now top-swing has become more the default, and other types of mounting problems bite you instead.