Triple front derailleur set up - help please

[curzons246]

I have set up and adjusted my triple front derailieur following Park Tools video. It all works fine except when moving from large chain ring to middle chain ring, it always skips the middle ring and drops to the small chain ring. No such problem on the way up just on the way down. Any advice please. Ps it's a road bike with shimano 8 speed STI's

 

[Rusty Nails]

If it drops to the small chainring from the outside it could possibly be that the tension in the cable is too slack. Put the shifter to lowest gear then increase the tension in the cable.

This is assuming you have the inner and outer ring limits set properly.

 

[curzons246]

Thanks for that, I'm sure the limits are set correctly, I'll try the tension tomorrow ( I've put everything away to watch the tennis).

 

[Ajax Bay]

Hope you enjoyed the tennis. I did.

 

[raleighnut]

The only thing that 'indexes' the middle ring is cable tension, you need to ensure that the cage is centred on the middle ring when it is selected.

The other thing that throws people is very often when the cable is correctly adjusted and the small ring is selected the cable appears slack
DO NOT attempt to take this slack out, it is perfectly normal, some set ups are worse than others though. The chain won't 'overthrow' if you have the inner stop set right but sometimes the cable 'slack' can be disconcerting.

 

[Mike_P]

I have a bodge for setting up triples, cable loose, gear lever set for the largest chainring, suitable wooden block positioned between the seat tube and the triple such that the chain is correctly on the largest chainring, cable tightened.

 

[Ming the Merciless]

Get a friction shifter. All this messing around with inferior indexed gearing.😉

 

[boydj]

If it drops to the small chainring from the outside it could possibly be that the tension in the cable is too slack. Put the shifter to lowest gear then increase the tension in the cable.

This is assuming you have the inner and outer ring limits set properly.

I think @raleighnut has it right. It's more likely the cable is too tight. There should be a touch of slack when the chain is on the small ring. There is a bit of trial and error to get it right, so experiment a bit with the bike on a stand if you have one.

 

[nmfeb70]

Thanks for that, I'm sure the limits are set correctly, I'll try the tension tomorrow ( I've put everything away to watch the tennis).

Nothing to do with the limit screws, probably cable tension. Get back & let us know.

 

[curzons246]

Ok, playing with the tension and using the wooden block method I got the drop from big to the middle ring. The shifter felt happier to, I've found the excess tension can lock the shifter. Release the tension and it operates ok. In this reduced state of cable tension though it doesn't lift cleanly if at all I'm afraid.

 

[Mike_P]

How old is the cable and the outer ? Could be they need replacing.

 

[curzons246]

Mike, the inner is new, I'll see if I can find a bit of new outer..

 

[curzons246]

The only thing that 'indexes' the middle ring is cable tension, you need to ensure that the cage is centred on the middle ring when it is selected.

The other thing that throws people is very often when the cable is correctly adjusted and the small ring is selected the cable appears slack
DO NOT attempt to take this slack out, it is perfectly normal, some set ups are worse than others though. The chain won't 'overthrow' if you have the inner stop set right but sometimes the cable 'slack' can be disconcerting.

Ralieghnut, your indexing on the middle ring has done the trick. Thank you very much indeed

 

[raleighnut]

Ralieghnut, your indexing on the middle ring has done the trick. Thank you very much indeed

It is the only way to get a triple to work,

Mike, the inner is new, I'll see if I can find a bit of new outer..

You may need to tweak it again in a couple of weeks if you've fitted a new inner cable as they do 'settle down' into position after some usage.