Caad 8 gears

[Moby Jones]

I am a bit frustrated with the gears on my 4 month old caad. I had a problem with the chain jumping off the small chainring so i took my bike to the LBS. The chap was able to get almost all the gears working apart from two which are not right, the chain is catching on the front Derailleur. I am going to take the bike back on Friday.
When i bought the bike from Evans the chap in the shop mentioned something about using the gear selector to trim the gears.
When i took it to my LBS he said the gears had been set up incorrectly and he had made what he felt were the correct adjustments. Like i said everything seems to be ok apart from two gears which i use quite alot.
Does anyone have any experience of the gears on a caad8 double sora

 

[Herzog]

Apologies if this is a basic question, but when you say "two are not right", do you mean the smallest rear cogs (when used with the smallest chainring)?

 

[Moby Jones]

Apologies if this is a basic question, but when you say "two are not right", do you mean the smallest rear cogs (when used with the smallest chainring)?

By not right i mean when on the biggest chainring on the first two gears the chain is hitting the front Derailleur, every other gear is fine

 

[Arch]

By not right i mean when on the biggest chainring on the first two gears the chain is hitting the front Derailleur, every other gear is fine

As far as I know, that's just how it is. I don't know what sort of gear shifter you have for the front mech, but on all mine, the shifter has small increments so that you can trim it correctly. When you change into those gears, you shift the front mech ever so slightly, a click or two, in order to clear the chain. (Actually, that's more likely to be an issue with the small ring I think, so perhaps not - but then I rarely use my biggest ring on a triple!)

Sorry, it's still not quite clear for me, though. The problem is when the chain is on the big chainring, but which sprockets is it on at the rear? The two largest, or smallest? 'the first two' could mean either, depending how you look at it... And is it catching on the inside or outside of the mech cage (the side nearer your bike, or the side nearer the pedal?)

If it's on the largest sprockets, and largest chainring, that's a combo you shouldn't be using. That gear will be available somewhere else in the range. If it's the smallest (the furthest out), then perhaps the high gear stop on the front mech needs releasing a touch, to let it move out a fraction more without throwing the chain completely.

 

[2Loose]

To quote the late Sheldon Brown

"Try to avoid the gears that make the chain cross over at an extreme angle. These "criss-cross" gears are bad for the chain and sprockets. Especially bad is to combine the inside (small) front sprocket with the outside (small) rear sprocket. This noisy, inefficient gear causes the chain to wear out prematurely."

Extreme angles of chain (Large chainring, smallest rear cog \ smallest chainring, largest rear cog) will almost always catch the edge of the front mech and therefore be noisy. Trimming the front mech as Arch suggests can help with the noise, but the angle of the chain will still cause extra wear.

Accept that this is the way it is and avoid those gears where possible.

 

[Herzog]

To quote the late Sheldon Brown

"Try to avoid the gears that make the chain cross over at an extreme angle. These "criss-cross" gears are bad for the chain and sprockets. Especially bad is to combine the inside (small) front sprocket with the outside (small) rear sprocket. This noisy, inefficient gear causes the chain to wear out prematurely."

Extreme angles of chain (Large chainring, smallest rear cog \ smallest chainring, largest rear cog) will almost always catch the edge of the front mech and therefore be noisy. Trimming the front mech as Arch suggests can help with the noise, but the angle of the chain will still cause extra wear.

Accept that this is the way it is and avoid those gears where possible.

Agreed, that's what I was getting at.

 

[Moby Jones]

It was ok when I first got the bike but the way it is set up now I cannot use the big chainring front with the big chainring rear, there is too much noise/rubbing of chain on front derailuer. I was able to trim my gears before but I cannot do that now I will take it in tomorrow and see what he can do

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[Arch]

It was ok when I first got the bike but the way it is set up now I cannot use the big chainring front with the big chainring rear, there is too much noise/rubbing of chain on front derailuer. I was able to trim my gears before but I cannot do that now I will take it in tomorrow and see what he can do

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See above, you shouldn't use the big ring and the big sprocket. Places the chain under too much strain, and will wear it all out quicker. That particular gear will be available somewhere else in your range with a straighter chainline since you are pairing 'high' at the front with 'low' at the back - that gear will be somewhere in the middle of your range. Have you got a double or triple set up front?

 

[Moby Jones]

It's a double,

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