Osella
Senior Retro Guru
Could be the BB width, but unlikely if you haven't changed it..
If you've set up a new front mech, it could be that the wire isn't tight enough, or more likely your limit adjustment screw is too tight and won't allow the mech to be pulled that far over. Best way to check is to turn the adjuster barrel on the shifter anticlockwise around 4-5 turns (go nuts - but take note of how much you turn it so you can undo what you just did!) and see if it gets any better.
If it does, you need to pull the wire tighter through the mech, if it it makes no difference then it's the limit adjuster screw.
Alternatively try pushing the mech cage out over the 3rd chainring by hand, if it won't go any further, it's the limit screw!
If you've set up a new front mech, it could be that the wire isn't tight enough, or more likely your limit adjustment screw is too tight and won't allow the mech to be pulled that far over. Best way to check is to turn the adjuster barrel on the shifter anticlockwise around 4-5 turns (go nuts - but take note of how much you turn it so you can undo what you just did!) and see if it gets any better.
If it does, you need to pull the wire tighter through the mech, if it it makes no difference then it's the limit adjuster screw.
Alternatively try pushing the mech cage out over the 3rd chainring by hand, if it won't go any further, it's the limit screw!