Gear Problem help please

[Davos87]

Been out on a ride today and for whatever reason the chain won't move onto the smalest chain ring of three. This is the first time this has happened?
What do I need to do?
Any advice on how I may be able to rectify this will be appreciated.
Cheers in anticipation.

 

[RecordAceFromNew]

It can be due to a variety of different reasons. Chief amongst those are probably a) gunged up cabling, b) gunged up front mech, c) front mech L limit screw too far in, d) twisted/bent front mech, e) shifter problem. This is a good guide.

Having put the shifter on low gear, you can get a feel of whether the cable/mech are gunged up by pulling on the exposed gear inner cable and see whether the mech snap back inboard quickly and smoothly. You can also check visually whether the mech is touching the L limit screw, whether the cage is parallel to the rings viewed from above, and why the cage outer is not pushing the chain onto the small ring.

 

[Davos87]

Thank you for the suggestions, advice and link to the park tools site. Will use that as my guide and attempt to fettle it over the weekend. Cheers.