Specialized Sirrus Front Derrailleur

cholasnjw

Hi,

I've recently bought a standard Specialized Sirrus.This is the first road-oriented bike I've owned - previously owned budget mountain bikes and a Dahon folding bike.

I'm having a problem with the front derrailleur and I don't know if it's something wrong with the derrailleur, the setup or my riding.

I'm finding that if I mis-time or misjudge changing down from the largest chain ring to the middle chain ring and the chain ends under higher than usual tension the derrailleur wont pull the chain onto the middle chain ring. The tension in the chain keeps deflecting the derrailleur. I did take the bike back to the shop and had them adjust it - no effect. I've also re-adjusted it myself with help from Sheldon Brown's website and my Park Tools manual.

So is this likely to be poor adjustment somewhere, or a fault with the front derrailleur, or just my riding? I've certainly never had this problem on my mountain bike, where even in top gear heading up hill the front derrailleur still pulls the chain to where it needs to be?

Any advice gratefully received.

Cheers,

Nick

CarlosDSanchez

Is the derailer running parallel to the chain rings? Is it clamped to the frame at the correct height? There should be about 1-2mm clearance between the bottom of the derailer and the top of the larges chain ring.

cholasnjw

Hi,

Thanks for the reply.

Yes the derailleur is at the right height and securely fastened. I've tried it in a few positions rotationally - parallel and rotated slightly, since some guides I've found suggest that rotating it may improve down shifting - doesn't seem to make much difference.

Once cadence starts to drop below 60rpm the shift from third chainring down to second becomes difficult or doesn't happen at all, even when I ease up my pedal stroke for the shift. Yet I know my mountain bike would not be having a problem.

I wonder if it would be worth trying the mountain bike derailleur on the hyrbrid as a comparison?

Any further advice will be gratefully received.

Nick

cholasnjw

I think I might have it sorted finally. Been out playing with it this afternoon.

I'm not sure what fixed it. I disconnected everything, removed the cranks, reattached the cranks and screwed them in, repositioned the derailleur and adjusted - now seems to be working OK.

Two things spring to mind - either the adjusting the cranks has altered the chainline slightly, or during adjustment I did notice under tension the chain seemed to ride up over the curvature of the derailleur plate, so I've positioned the derailleur slightly higher.

Anyway. will get out for a good ride tomorrow and see how it goes - will report back afterwards.

Nick