Bicycle Mechanics - Adjusting road bike front derailler

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nrsmd
08-03-12, 01:08 PM
Looking at videos, it is still unclear to me how to use the high and low screws adjustment screws for the front road bike derailler. When the chain is on the small cog in front and large cog in rear, how do I position the cage with regards to the chain. They books and videos say to leave 1-2 mm clearance between the cage and chain, but they don't clarify if that tolerance is for inner edge of the cage near the wheel or outer edge of the cage near the pedals.

Drew Eckhardt
08-03-12, 01:23 PM
Looking at videos, it is still unclear to me how to use the high and low screws adjustment screws for the front road bike derailler. When the chain is on the small cog in front and large cog in rear, how do I position the cage with regards to the chain. They books and videos say to leave 1-2 mm clearance between the cage and chain, but they don't clarify if that tolerance is for inner edge of the cage near the wheel or outer edge of the cage near the pedals.

The inner edge near the wheel.

The idea is that you need enough clearance to avoid rub when the chain is as far inboard as it will go, but not so much derailleur movement inwards that you can shift beyond the small ring and drop the chain on the bottom bracket shell.