FD cage not moved by limit screws

[TwickersDave]

Hi,

I've got an issue with my front derailleur whereby I can only adjust it by using the barrel adjuster. When I use the limit screws nothing happens. It shifts OK when using the lever but I'm getting too much chain rub which I'm sure is affecting the shifting on the rear derailleur, but I can't do anything about it until the front derailleur is sorted. It's a Shimano 105 FD, RD and levers.

Any ideas?

 

[bpsmith]

The Park Tools site is superb for step by step advice on maintenance. Really easy to follow too. Just start from scratch and follow the whole process:

http://www.parktool.com/blog/repair-help/front-derailleur-adjustments

 

[Brommyboy]

The limit screws determine to limit of movement, ie the stop to the travel. The barrel adjuster effectively changes the cable length. If this does not provide enough movement, then the cables itself may need re-adjusting. If the FD is a narrow cage, then the chain will rub unless you adjust its movement slightly using the gear lever.

 

[raleighnut]

^^^^^^ +1

 

[TwickersDave]

The limit screws determine to limit of movement, ie the stop to the travel. The barrel adjuster effectively changes the cable length. If this does not provide enough movement, then the cables itself may need re-adjusting. If the FD is a narrow cage, then the chain will rub unless you adjust its movement slightly using the gear lever.

Understood, but what I'm saying is that the limit screws do not move the cage, even if I slacken the cable right off using the barrel adjuster. I can screw either of them right in or out and nothing happens.

 

[raleighnut]

Understood, but what I'm saying is that the limit screws do not move the cage, even if I slacken the cable right off using the barrel adjuster. I can screw either of them right in or out and nothing happens.

It won't

 

[TwickersDave]

It won't

So the point of those two screws is?

All the maintenance stuff I've looked at says adjust the inner clearance before attaching the cable, so if you don't use the limit screw then how is it done?

 

[raleighnut]

Push the mech by hand inwards (no chain) the inner screw should stop the mech from going any further than you want it to, if it does go too far screw it in a bit and it will stop the mech sooner. They are both travel limit stop screws and neither will move the mech they simply stop it from moving.

 

[TwickersDave]

Push the mech by hand inwards (no chain) the inner screw should stop the mech from going any further than you want it to, if it does go too far screw it in a bit and it will stop the mech sooner. They are both travel limit stop screws and neither will move the mech they simply stop it from moving.

Ok, the haze is clearing. Will try it tonight. Thanks.

 

[bpsmith]

I don't agree. The inner limit screw will move the mech at its lowest point, as it needs to in order to stop the chain movement when in use. The same goes for the outer limit. If the OP is not seeing ANY movement of the mech when adjusting the lower limit with no tension on the cable, then something's wrong.

I agree that whilst in use, they do not affect the shifting of the chain, but they certainly do move the mech when adjusting. That's assuming that they are being adjusted with or without tension and in the right positions when doing either lower or upper limit.

The Park Tools link explains very easily from start to finish.

 

[raleighnut]

You must have very strong hands to move the mech against its spring using the stop screws.

 

[DaveReading]

You must have very strong hands to move the mech against its spring using the stop screws.

Nonsense.

 

[Brommyboy]

Without the cable attached, the cage defaults to its inner position. Adjusting the inner stop screw should move the cage at this point. Pulling the cage outward to its limit can be done with the cable attached if you like, and the screw will adjust to alter this outer position. These two positions are set merely to prevent the chain from over-running the inner or outer chain rings. They have no bearing on the actual gear adjustment for gear changes.

 

[TwickersDave]

I don't agree. The inner limit screw will move the mech at its lowest point, as it needs to in order to stop the chain movement when in use. The same goes for the outer limit. If the OP is not seeing ANY movement of the mech when adjusting the lower limit with no tension on the cable, then something's wrong.

I agree that whilst in use, they do not affect the shifting of the chain, but they certainly do move the mech when adjusting. That's assuming that they are being adjusted with or without tension and in the right positions when doing either lower or upper limit.

The Park Tools link explains very easily from start to finish.

This, especially your first paragraph, is what I was expecting when trying to sort it out last night. So if some is wrong with the FD, any ideas what it might be? Or is it a trip to the lbs?

 

[raleighnut]

This, especially your first paragraph, is what I was expecting when trying to sort it out last night. So if some is wrong with the FD, any ideas what it might be? Or is it a trip to the lbs?

Try screwing the inner limit screw in until it stops, then move the shifter lever so the mech moves out you should now be able to screw the limit screw in a bit more. I find it impossible to move my 105 front mech out just by turning the limit screw.