Chain won't shift to large chainring (Tiagra)...

[Shearwater Missile]

I think what can also happen is over time the cable will wear the plastic of the guide because of friction and the grit etc. It may be as well to think about changing it anyway, if that has been there a long time. I know on my summer bike, despite keeping everything clean, there was a groove and the cable got closer to the frame as a result. Just a thought.

 

[Mazz]

I think what can also happen is over time the cable will wear the plastic of the guide because of friction and the grit etc. It may be as well to think about changing it anyway, if that has been there a long time. I know on my summer bike, despite keeping everything clean, there was a groove and the cable got closer to the frame as a result. Just a thought.

Very good point. With all that grit and toing/froing of the gear cables, you could be right. I'll have a closer look, cheers.

 

[Ming the Merciless]

Yes mate, I flipped the bike over to look at the cable runs under the BB. It was a mess, but I've cleaned and greased it now. Bang on, smoothness of shifting has improved significantly, cheers.
View attachment 799421

Was that found in a 4,000 year old pyramid?

 

[Punkawallah]

Looking at the picture it looks like no one’s cleaned it since 2013.😉

Slut :-)

 

[Mazz]

Was that found in a 4,000 year old pyramid?

Round here, CC doesn't stand for Cycle Chat, it stands for Carter & Carnarvon 👍

 

[Shearwater Missile]

Very good point. With all that grit and toing/froing of the gear cables, you could be right. I'll have a closer look, cheers.

I am not sure if some guides are made from different grades of plastic. The one of mine which was worn had done a lot less miles and dry miles at that. I tend to use the Shimano ones now, even if I have to modify to fit: That was because when my Vitus one needed replacing CRC could not supply the correct one, it goes through the frame. Anyway, hope it helps for the future should it start again.

 

[gbb]

It could be because your front derailleur is filthy. A clean and a couple of drops of oil wouldn‘t do any harm in easing the force needed.

Certainly with my old Sora front mech, always in winter, corrosion would build in the pivot and cause a complete sieze.
Slightly undo (NOT Remove) the rearward facing pivot bolt, apply some penetrant or oil, manipulate that pivot bolt and it would always sort itself out. Retighten, ride.
I dont know if Tiagra mechs have the same principle pivot tbf.

 

[the_mikey]

Seemed to working fine on the ride this morning.
I was a bit surprised that by them replacing the rear wheel, that the front derailleur mech was affected - although that might be down to the impact with the car/road as the bike fell onto the drivetrain. Maybe that messed up the front derailleur settings. No idea.

A worn or damaged cable can sometimes cause this, the cable guide in the Tiagra shifter is not very forgiving of some shifter cable diameters and seems to encourage their self destruction.