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I replaced my 3rd front gear with a bash guard. I still get rubbing on the derailer when I have big on big or small on small even though it is a 2 speed front set. Is there a way to shift the position of the cassette to maximize availible gears. I imagine the position is maximized for a 3 speed front set. Or am I being a silly rabbit
 

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you shouldnt need to cross chain, you're using duplicate gear ratios that can be accomplished without cross chaining, so big big is fine (since your "big" is now really a middle chainring) but small small is completely pointless. if you have an 8 speed bike, stay above 6th in the rear when in the small ring up front. and no, you can't change the position of the cassette. you can also check to see that your front deraileur is positioned properly on the seat tube.
 

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Iridethedirt said:
you shouldnt need to cross chainThat is BS, you're using duplicate gear ratios that can be accomplished without cross chaining, so big big is fine (since your "big" is now really a middle chainring) but small small is completely pointless. if you have an 8 speed bike, stay above 6th in the rear when in the small ring up front. and no, you can't change the position of the cassette. you can also check to see that your front deraileur is positioned properly on the seat tube.
Cross chaining serves several useful purposes, secondly any good drive train can cross chain and preform...yes it will decrease efficiency and increase wear...

On a triple chain ring bike, with the big ring removed the only possible cross chaining is little to little....I have not needed that chain option...I have needed big to big...

Anyway the FD should not rub the chain even when cross chained.

So you need to get the FD set-up properly...

It is all about the shifting bumps on the FD, and the height of the FD above the big chain ring (big is easiest to measure)...

So if you are converting a triple rig to a double with a bash guard you still need to figure out how to set-up a triple properly.
 

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Use the deraileur noise to let you know you are where you shouldn't be.

Or use a Sram left shifter so you can trim the deraileur position.

Or try putting the tail of the front deraileur out slightly to clear small to small cross chaining.

There are many different designs of cages on front deraileurs. Some are better at clearing cross chaining.

Or just get with the program...
 
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