Chainring or rear mech mis-alignment or neither?...

[TonyEnjoyD]

Hi,

On my roadie - Giant SCR3 upgraded to 105 5600 groupset, if I back-pedal, the chain rolls off to the inner ring if on the large chainring or onto the BB if the smaller.
Shifting and general running is perfect with no change lag, rattles or catching the mech cage (either front or rear)
As I never back-pedal on the move, this only happens when clipping in to move off and the pedal has moved forward and I need to bring it up to move off.

So, what do the experts on here reckon?

Thanks
T

 

[the_mikey]

Aside from the front derailleur limits (the FD should stop the chain ejecting onto the BB), could it be a chainline issue?

 

[TonyEnjoyD]

Tbh @the_mikey i think it only happened after I upgraded to 105 from Sora, so may well be that!
Cheers
T

 

[solidthegreat]

Tbh @the_mikey i think it only happened after I upgraded to 105 from Sora, so may well be that!
Cheers
T

Pretty certain it's the limiter screws (h & V). Shift to small ring at the front and large ring at the rear and adjust H V screws 1 turn at a time and test. You should see the derailleur move. Adjust so You have only a mm or so between the back plate and chain of the fd.
Then put it in the big ring front and small ring at the back and adjust the other screw so it is about a mm or so from the inside of the front plate of the fd. Then test and index the gears.
Hope this helps.

 

[screenman]

If you back pedal then the chain is being wound back under the chain ring, so I would say front mech has no connection with the problem. Rear mech hanger alignment maybe.

 

[Lanzecki]

Sticky freewheel or Jockey wheel?

 

[Lanzecki]

Just found this http://www.cyclechat.net/threads/de...orward-when-freewheeling.143696/#post-2776144

 

[TonyEnjoyD]

Thanks all - I'll SE if I can fettle it
T