Completly re-setting front derailer

Piersy Boy

Hi,

After some advice - my friends Giant TCR 3.0 front derailer is not shifting correctly or at all for that matter. We have tried to adjust the stops and wire tension but to no effect.

The mech isn't bent so it should be working fine.

I think the solution is to take it apart and fit it back together from scratch - however, i have never done this before and so would like so do's and dont's and any tutorials you can guide me towards!

Thanks in advance.

neeb

What brand and model is the derailleur?

What happens when you try to shift, i.e. in what way is it not working?

Monty Dog

www.parktool.com

Worth removing the mech and giving it a good clean to ensure that any muck preventing movement is removed. Work the pivots by hand to ensure that they aren't sticking.

Alignment is critical - parallel with chainrings and edge of cage clears big ring by 1-3mm

Piersy Boy

neeb wrote:

What brand and model is the derailleur?

Shimano Sora

What happens when you try to shift, i.e. in what way is it not working?

When shifting, the derailer barely moves. even though the wires move.
Wont drop onto the lowest gear (of 3) but will only shift up when on middle gear.

Hope this helps and makes sense!

neeb

When you try to shift onto the smallest chainring, do you end up with a lot of slack in the cable, i.e. the cable is relaxing but the shifter not moving inwards? If you push the derailleur inwards by hand (after trying to shift down) and then turn the cranks, can you get it to shift, or will it not move at all?

lucan

Have a look on youtube for "front mech adjustment". There are plenty of demos which helped me when I was failing badly setting mine up.

R8JimBob88

Have you had a play with the adjustment screws? Mine was out not long ago, wouldnt shift to the big front ring

Piersy Boy

neeb wrote:

When you try to shift onto the smallest chainring, do you end up with a lot of slack in the cable, i.e. the cable is relaxing but the shifter not moving inwards? If you push the derailleur inwards by hand (after trying to shift down) and then turn the cranks, can you get it to shift, or will it not move at all?

Exactly what you have said - it just wont shift over, even when manually holding the derailer across and then turning the cranks.

What do you suggest?

Thanks

woodywmb

Inner limit screw needs adjusted. But you should go through one of the online tutorials and study the Park Tools site so you know how to set the indexing.

itboffin

Park tools is your best bet http://www.parktool.com/blog/repair-hel ... djustments

Get the height right, then start as it says with the smallest chainring at the front and the rear on the largest sprocket, get the low gears set up without worrying too much about the high & low screws at first, then set the high gears, biggest chainring, smallest sprocket.

Once you've done those you can start on the high/low screws, which wont take must unless you've already adjusted/fiddled.

Watch this video http://bicycletutor.com/adjust-front-derailer/ then use the park guide.

morstar

Has it been cleaned at all or is there a possibility it is simply ceasing up?
Not trying to cast aspersions on the cleaning regime but it does happen.
If gunked up, lots of lube, slacken the cable and move by hand to gradually free up the mech.

neeb

If you're sure that turning the correct adjustment screw all of the way out doesn't allow it to shift down, and if there is slack in the cable after operating the lever to shift, then it must be a problem with the derailleur itself or with the way it is clamped to the seat tube (too high up or down, not angled correctly). If it was working fine before, then it's probably the derailleur. See Monty Dog's advice above!

Monty Dog

FWIW I've only ever had one front mech go wrong - they're so simple and most are pretty robust. 99% of time it's due to poor alignment / set up or where a forced shift pushes the chain between the cage and the chainring and mangles it. For some reason, people start tinkering with the stop screws when they don't understand how they work.