Problem: when the smaller chain ring is selected, the chain is well centered in the front derailleur's bracket but is rubbing against its lowest part. See the shredded rubber remains there? It happens not only with quick rear gears but with slow to medium rear gears as well.

I noticed this after replacing the crank set and was about to blame it. However, the new set is identical to the original one, 36T/22T Shimano FC-MT210-2. Given the state of the rubber pad Y-2CL00080 of the front derailleur, the chain probably rubs since long time and it simply became audible recently now that no rubber separates the chain and the derailleur.

The rotation of the derailleur around the seat tube cannot solve the rubbing since it does not increase the vertical gap to the chain.

I can't move the derailleur further down along the seat tube - it would touch the bigger chain ring.

The derailleur FD-M3120 is for the correct teeth difference (14T=36T-22T). But I wonder if it is for the correct seat tube angle. This tilt is not adjustable; the imprint says 64°-69°.

Am I missing any other degree of freedom to fiddle with? front derailleur crank set

Added: The seat tube has a kink close to where the front derailleur is mounted. Without this kink, the angle between seat tube and chain stay would be 68°. The kink adds about 5.3°, bringing it outside the range imprinted on the derailleur. It probably would work if the small chain ring had more teeth. seat tube kink seat tube angle reading chain stay angle reading

Even with the derailleur down the seat tube and touching the large chain ring, the chain firmly rests in the derailleur's bottom point already with the third fastest rear gear is selected, let alone faster ones. chain still rubbing

At the end, I only managed to make four slowest rear gears usable. For the record: https://www.scott-sports.com/de/de/product/scott-aspect-940-orange-bike (size XXL).


1 Answer 1


It may be a matter of millimeters, so even if you state that you cannot, I would try to move the derailleur down along the seat tube. From the perspective of the second picture it looks like 3 mm to the bottom and you will have both clearance for the chain and for the big gear when moving up.

Another explanation is that your L-limit screw moved slightly, preventing the derailleur from swinging as before. So the derailleur swings a bit less towards the interior and towards the bottom.

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