Front Derailleur Won't Shift Up When Pedaling

[marcdominic]

I agree with JonB, chain suck is primarily caused by a worn rear cassette or worn front chain rings. Have you recently changed the chain? A chain tends to wear into the worn cassette and sprockets so everything gradually functions normally but when you make a change… Moreover, this is most likely to happen on changing the rear cassette but keeping the same old (worn) chain.

If so this is most likely your problem…

I ought add [edit] that a fully replaced cassette with a brand new chain and worn front chain ring will cause similar issues…