Front mech not throwing chain onto big ring

[wisdom]

Sons bike is an oldish giant boulder with mid range shimano gear.It's no longer shifting up onto the big chain ring.Cables very tight and there doesn't seem to be any more movement on the front mech.It was working ok until last week.Any ideas please.

 

[cyberknight]

Does the H screw need adjusting ?

 

[pclay]

It may have siezed. If it has, liberal spray of wd40, or take off and soak in olive oil overnight.

 

[Tim Hall]

As it used to work but now (suddenly) doesn't, I'd be looking for mechanical damage. Has it had a knock? Is it parallel to the chain rings? Is the cable damaged? Perhaps frayed where it leaves the shifter.

 

[Cycleops]

Front mechs are very simple affairs but they can go out of adjustment or get knocked or cable gets stretched. Here's a good guide to adjusting: http://www.parktool.com/blog/repair-help/front-derailleur-adjustment

 

[wisdom]

Thank you all for your replies. It would appear one of his mates adjusted it for him at work.Adjusted it so much that the H screw was screwed right in.I have advised him accordingly

 

[Dogtrousers]

With mates like that ...

 

[Smokin Joe]

With mates like that ...

That's a common "Solution" applied by people who only have a scant knowledge of cycle mechanics. First sign of rough shifting start fiddling about with the stops, the very things that never need adjustment after the initial setting.

 

[gbb]

That's a common "Solution" applied by people who only have a scant knowledge of cycle mechanics. First sign of rough shifting start fiddling about with the stops, the very things that never need adjustment after the initial setting.

Agree wholeheartedly. It's the LAST thing I consider, stop screws just don't un adjust themselves IME

 

[wisdom]

Exactly