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I have MTB bike with 3x7 speed groupset.

Then I replaced the FD Shimano tourney by a Deore FD-M590-10 (with with top pull). Is it a 3x10?

But the shift (Altus ST-EF50-L) can shift only the 2 (the smaller) chainrings because it can't complete pulling for the 3rd one.

Note that the top/max screw is not stopping the movement

are using different pull distances? Is it normal or i installed something wrong?

Additional info:

  • Chainring 42x34x24 T
  • Loss the alineation pro-set
  • Freewheel MF-TZ21 (maxcog 28T)
  • FD-TZ20 tourney (the previous)

shimano service pdf

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  • I replaced the Deore FD 3x10 by a Tourney FD and I am facing the same issue. Can the problem be caused by the shift?
    – Daniel Perez
    Commented Jan 13, 2023 at 9:24

1 Answer 1

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Pull ratios should be the same, but in the case of front derailleurs, the critical dimension is the chain outer width. 10-speed chains are between 5.84mm and 6.1mm, while 7-speed ones are 7.3mm. So a 3-speed jumps might be too big.

2x are less sensitive to that, because moving to the big chainring only requires the inside part of the cage to be at the right position, and (the outer part of the cage to move to the small chainring), so you have more margin to play with the stops and tension. But in the case of 3x, it's much harder, as the cage needs to be correctly positioned for each chainring.

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  • The Chainring is 42x34x24 T and max CogRing 28T. Anyway it seems that the shift want to more pull more cable than the FD capacity, so FD is stopping the to achieve to reach the 3rd gear shift
    – Daniel Perez
    Commented Jan 7, 2023 at 14:44
  • The capacity is not a relevant metric here. Because of the wider chain, you have to cheat (combination of stop and barrel adjustment) and cause a larger movement than what the FD is designed for. Which means skewed towards the center if you adjusted it on the small/medium. To shift to the big, you would need standard actuation + the chain width difference.
    – Rеnаud
    Commented Jan 7, 2023 at 21:01

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