Front derailleur design question

[cnighbor1]

Front derailleur design question.
Why couldn't the two sides of a front derailleur be just a bit wider. Seems ever time I install a front derailleur one of the sides hit the chain. If opening just say 1/16" wider than it would make adjusting easier. Yes a bit more cable to wrap up but I would take it n making it easier to adjust. Yes I rotate till position is correct.

[zmalwo]

it would mess up down and upshift and the lower and upper limit.

[robt57]

Make sure your cable length is set to make best advantage of the trimming features of the shifter in use. And defiantly have the cable centered in pull with regards to the DR limit adjustments.


Some shifters are way better than others with trim positions.

[Mark McM]

There are several reasons it probably isn't a good idea to make the front derailleur cage wider. The cage plates on a front derailleur do two things: One plate pushes the chain laterally, until it either catches on the adjacent chainring (shifts to bigger chainrings), or pushes it off the chainring (shifts to smaller chainrings; and the other plate keeps the chain from going to far, and falling off the chainrings. Making the derailleur cage wider would hamper this secondary function of keeping the chain from shifting too far. In addition, when in the large chainring, there is very little clearance between the derailleur cage and the crank arm, so there is little room to widen the cage much.

Typically, the chain rubs at the rear of the derailleur cage, not at the front. The front portion of the derailleur cage has to remain narrow to prevent over-shifting, but derailleur designers often widen the rear of the cage to help limit chain rub. A well designed front derailleur can be adjusted so that there is no chain rub at all in the large chainring, and only minimal rub when the small/small chainring/sprocket combination (which you shouldn't be using anyway).