Shimano Front Derailleur Triple Vs Compact

Maggers

When I got my new road bike it was originally fitted with a Shimano Tiagra Triple. The shop had managed to offer me an upgrade to a 105 Compact and changed it over. I'm not sure if they changed over the Derailleur to though. There's not a lot of clearance between the Derailleur and the crank when it's set up to get the chain up smoothly from the small to big ring. With the screws wound out as far as they'll go it's still not enough to give me the shift up 100% of the time. Is there a way of knowing if it wasn't changed or do the Derailleurs have the same sizes for compact and triple and it's just me having the wrong set up?

cheers

ben16v

pretty sure the differences lie with the shifters and not the deraillier, sounds like the cable is too long and a bit of slack needs taking out - that should be possible with the adjusters on the downtube. the screws are there to stop itgoing off either side of the rings - but take it back to the shop and get them to tune them

keef66

If you look at the pics of 105 front mechs on eg Wiggle or CRC you'll soon see that the triple mech has a much deeper inner plate than the double

http://www.wiggle.co.uk/shimano-105-570 ... r-t-braze/

http://www.wiggle.co.uk/shimano-105-570 ... ur-d-band/

Edit: sorry, I read 105 compact in your OP. Same with Tiagra though.

Front shifting with a triple mech and a compact crankset is always going to be a bit clunky / trickier to set up.

Maggers

cheers for the replies. I see what you mean about the 2 wiggle links. With a bit of elbow grease I've uncovered that the derailleur installed is a FD 4603 (i.e. tiagra triple). I'll get meself a double, anyone got reasons for going for Ultegra over 105? I'm changing out the cassette and big chain ring which are both 105. Guess it's best to stay with the same grade throughout?

*update*
other than the price anyone tell me what the difference between these two is? Braze Vs Band?

http://www.wiggle.co.uk/shimano-105-570 ... ur-d-band/

http://www.wiggle.co.uk/shimano-105-570 ... r-d-braze/

keef66

Maggers wrote:

cheers for the replies. I see what you mean about the 2 wiggle links. With a bit of elbow grease I've uncovered that the derailleur installed is a FD 4603 (i.e. tiagra triple). I'll get meself a double, anyone got reasons for going for Ultegra over 105? I'm changing out the cassette and big chain ring which are both 105. Guess it's best to stay with the same grade throughout?

*update*
other than the price anyone tell me what the difference between these two is? Braze Vs Band?

http://www.wiggle.co.uk/shimano-105-570 ... ur-d-band/

http://www.wiggle.co.uk/shimano-105-570 ... r-d-braze/

They are the same price. Difference is how they attach to the bike. Band is a clamp that goes round the seat-tube. Braze bolts directly on to a slotted mount which your bike frame already has (on steel frames this mount was brazed on when the frame was built, hence the term)

Which you need depends on whether your frame has a front mech mount or not.

gozzy

I trust they changed your shift lever to a double one.

Maggers

Is there an easy way to tell? Feel I may have been stitched a little...

francis666

I have swapped and changed both triples and compacts so here's a few working knowledge facts.

A triple will have a rear mech/derailleur (hate spelling that!) with a long cage to take up the extra slack that is created from the need to have a longer chain to cope with the greater size difference between the smallest and largest chain wheels compared to a compact.
Triples tend to be better for Hill work as they give a much larger range/higher gearing (the smallest chain wheel is much smaller than that available on a compact)
A long cage rear mech can also be used on a compact (double chain ring), but means your using a little more chain than needed and thus a slight weight penalty.
A small cage rear mech/derailleur cannot be used for a triple (unless you remove one of the outer chainrings, giving you a homemade compact).
I have actually removed the inner chain ring form a triple so that my Ultegra short cage rear mech would still work (more than once and it does very well).
The front mech of a triple can be used for a compact by adjusting the max - min screws so that the third chain ring will not engage (as its not there it would make the chain come off). You can even still use the triple front mech lever like this as it cant go to the third position as the max-min screws will stop it.
You obviously cant make a double front mech/lever work for a triple, as there simply isn't any indexing available or position for the mech to go to.
One of my bikes is home made Hybrid. Originally a Claude Butler MTB. It now has 700c wheels on it and a short cage Shimano Utlegra rear mech. The English BB was ruined from years of use, so I put a Shimano Hollowtech 2 BB on it and a triple Deore MTB/Hybrid (largest chainwheel is 48T instead of normal MTB 44T). I removed the smallest chainwheel and it now works well as a double on a triple front lever and triple front mech. The max -min screws adjusted to stop the chain falling off where the smallest wheel used to be.
With you specific problem, can be two reasons the front mech is not going out far enough: (most likely) The cable is too tight (loosen it off) but then adjust the max screw or the chain will fall off) or second (unlikely), they have put too many spacers in the bottom BB pushing the cranksett to far out. Your bike is new and its got 105, then it will have a Hollowtech2. This can push the crank out just a bit too far for the front mech to reach.
If your shop did this work for you, then bring it back and get them to sort it!
Francis