Chain rubbing on front derailer

[Distorted Vision]

I was testing the gears on my brand new Cannondale Synapse whilst it was in the workstand before I rode it. I noticed that the chain was rubbing on front derailer when it was in the smallest chainset and smallest sprocket on the cassette. It is perfect in other gears.

Is there something wrong or is it merely a gear I should avoid using?

 

[Grant Fondo]

Yeah avoid

 

[lazyfatgit]

You should avoid using small-small and big-big gears.

 

[OldShep]

You should, but have you trimmed it?

 

[roadrash]

As said cross chaining should be avoided, see here..
..https://wickwerks.com/support/crosschaining/

 

[Distorted Vision]

Okay great thanks.

 

[Cycleops]

If brand new you should return it to the supplying dealer who should sort it for you.

 

[CXRAndy]

'cross chaining' is not the best way to ride. You're placing the chain in a 'S' shape which creates added friction and increased wear on the chain and sprockets.

Use small chainring with the 5 easy gears and big ring on 6 harder gears.

 

[Slick]

Okay great thanks.

Everyone is quite right about the cross chaining but you could either trim that front derailer or try adjusting it to reduce that rubbing.

 

[Yellow Saddle]

If brand new you should return it to the supplying dealer who should sort it for you.

No, c'mon. You've been in this game long enough to not say stuff like that.

 

[Yellow Saddle]

Cross-chaining, whether riding big/big or small/small, is a no-no. It puts great strain on the chain, sprockets, chainrings and jockey wheels.

It grinds the chainrings down by making them thinner, which then leads to pressure bulges. It also grinds down the sides of the jockey wheel and causes it to derail, with catastrophic rendezvous for chain, spokes and derailer. Sometimes the right chainstay also joins the party and it is game over.

Don't do it. Just consider those gears as not available to you. On electronic systems those are blanked off and the system will change so that you cannot cross-chain.

 

[raleighnut]

Is that the chain rubbing on the sideplates of the front mech or on the bottom 'joiner' pin?

 

[Cycleops]

No, c'mon. You've been in this game long enough to not say stuff like that.

True, but they might be able to minimise it but using it like that is not a good idea.

 

[fossyant]

True, but they might be able to minimise it but using it like that is not a good idea.

No they won't - chains rub in big big / small small especially on 8,9,10,11 speed cassettes. Might get away with a 5 speed !

 

[Yellow Saddle]

True, but they might be able to minimise it but using it like that is not a good idea.

You are digging a bigger and bigger hole for yourself.
No amount of fiddling with the derailer can fix the fact that the chain, in a cross-chain position, has to run along a diagonal line from front to back. The shorter the chainstay, the more obtuse the angle. Further, that angle is not made up of a gentle curve of the chain. No, it is made up of a hard bend where the chain exits the front sprocket and an equally hard bend where the chain enters the rear sprockets. The two sprockets cannot accommodate a diagonal line, therefore the chain has to flex.
A scraping FD is actually a blessing because it warns you of you doing illegal stuff with the chain. Put it out of its pain and shift.

Lastly, encouraging people to take it back to the shop only distributes the BS. Now the poor shopkeeper has to educate the customer who is already in a state of brainwashing thanks to internet wisdom.