Indexed gears and a noise.

[howard2107]

I have set up and indexed my rear gears (9 speed shimano), and they run bang on. I have also done the same to the front mech (3 ring shimano), and they also change nice and crisp, but! I have tried all sorts of adjustments to stop the chain catching on the front mech cage when its in largest at the back and largest at the front, and smallest back and smallest front. It only just catches it and its more of an annoyance than a problem. Any ideas what maybe wrong, or is it just down to fine adjustment and trial and error? I can't see any damage or mis alignment with the mech, and it appears to be parallel to the chain ring.

Cheers.............Howard

 

[screenman]

Do not use those combinations then.

 

[mythste]

Do not use those combinations then.

In a slightly less abrupt way, I'm afraid screenman is right.

Cross chaining like that is not advisable and will lead to premature chain and casette wear.

Source: I cross chained all the time and buggered my chain

 

[jazzkat]

As above, largest at the front and largest at the back is called cross chaining, it is mechanically really bad for your chain and sprockets. Ideally as you get to the middle of the rear sprocket-set you should change down to the middle ring. This will be kinder to your chain. In the middle (front) ring I'd avoid using maybe the lowest and highest gears at the back but you shouldn't have too many problems. Conversely if you were riding in the smallest front ring, after you've changed up maybe two or three gears my next move would be to change up at the front.

Once you get used to it it's actually better as you always have a couple of gears either side of where you are (except at the very highest and lowest).
Hope that helps.
Apologies if this comes across as teaching your granny to suck eggs, I just wanted to give a thorough answer

 

[pawl]

I have set up and indexed my rear gears (9 speed shimano), and they run bang on. I have also done the same to the front mech (3 ring shimano), and they also change nice and crisp, but! I have tried all sorts of adjustments to stop the chain catching on the front mech cage when its in largest at the back and largest at the front, and smallest back and smallest front. It only just catches it and its more of an annoyance than a problem. Any ideas what maybe wrong, or is it just down to fine adjustment and trial and error? I can't see any damage or mis alignment with the mech, and it appears to be parallel to the chain ring.

Cheers.............Howard

Yes don't cross chain.Some one will be along to explain in detail.

 

[raleighnut]

My triple equipped bikes only have 7 at the rear so I can end up shifting as much at the front as at the rear.

 

[themosquitoking]

My triple equipped bikes only have 7 at the rear so I can end up shifting as much at the front as at the rear.

That's excellent. Keeps both hands exercising the same and therefore roughly the same size.

 

[DaveReading]

I have tried all sorts of adjustments to stop the chain catching on the front mech cage when its in largest at the back and largest at the front, and smallest back and smallest front. It only just catches it and its more of an annoyance than a problem. Any ideas what maybe wrong, or is it just down to fine adjustment and trial and error?

The difference in the chain angle between the large-large and small-small combinations is so great that the chain is pretty well bound to rub on one or both sides of the front derailleur cage if you use those combinations. No amount of adjustment will make any difference.

 

[shouldbeinbed]

What they all said, you need ro consider your front and rear gears as a single entity and shift them often in combination to keep the line of your chain running straight, not diagonally and as parallel to the cogs & teeth as possible to save premature wear and damage to the parts.

 

[sgl5gjr]

as others have said.... cross chaining..... however as a caveat... I do set up in the workshop as near as dammit as I can get the chain not to rub, sometimes it a fag paper thickness in it...lol.....but when you are on the road and the legs are working....it'll rub..

 

[howard2107]

Great, many thanks for the replies, i do see the sense and reasoning behind what has been said. I generally don't cross chain anyway, but i thought i could adjust it out. At least i know that they are now all adjusted properly. Once again fantastic advice and info, form a first class forum.