front derailleur won't go largest cog

[Peter Wang]

Hi, I had a shimano 505 front derailleur, when the shifter in 3, it won't go to largest cog, stay in middle cog, the cable is tight enough, if I pull the cable manfully, it will go to the largest cog. here is pictures, who can help me to fix it?

peter

[Jesper]

(06-21-2021, 07:03 PM)Peter Wang Wrote:  Hi, I have a shimano 505 front derailleur, when the shifter is in 3, it won't go to largest cog, stays in middle cog, the cable is tight enough, if I pull the cable manually, it will go to the largest cog. here are pictures. Who can help me to fix it?

Hi Peter and welcome,

The FD is a C050 model. Your shifter cable may have too much slack possibly from stretching. Shift the derailleur onto the smallest gear and continue until the derailleur cage stops moving inward. If the cable has slack, you may be able to remove it by adjusting the cable tension at the shifter (grip?) and/or cable stop if it has a barrel adjusters. I think some Shimano grip shifters have a means of unclamping the cable at the shifter barrel adjuster where there is a set screw or some sort of fastener that can be loosened up to remove excess cable slack. If none, or if there is not enough adjustment available; loosen up the cable clamp nut/bolt on the derailleur and try to pull any slack out of the cable. Check your innermost and outermost cage movement to ensure you won't drop a chain because the low and high limit screws are improperly set. A little lubricant on the cage and control arm pivots might not hurt either (or remove and completely service the FD). You might want to post a photo of that shifter (grip?) to give us an idea as to adjustment options.
If you can't get it straightened out, it should be a quick, easy, and inexpensive fix at a shop barring any damage to the derailleur or other related components excepting the cable itself which low in cost.

Good luck.

[Jesper]

Forgot to ask it the bike has been in an accident or stored outside exposed to the elements. Both could be directly or indirectly related to your present, and I assume only, problem.