Campy RD limit screws vs. Shimano's ??

[DHallerman]

Limit screws may be real basic stuff, but I want to be sure since in the near future I'll be installing my first Campy RD (Centaur 11) after years of installing lots of Shimano RDs.

Now if you don't know, the instructions for every Shimano RD I've seen have you adjust the low limit screw so that the jockey pulley is directly beneath the biggest cog. But the high limit screw should be adjusted so that the jockey pulley is just to the outside of the smallest cog. Kinda like the left side of the pulley virtually touches the right side of the smallest cog when viewed from the rear. I've always done it that way, even when using Jtek Shiftmates, and it works well.

So what about Campagnolo? I'm guessing Campy's RD limit screws need to place the jockey pulley directly beneath both largest and smallest cogs. Is that correct? Do the two brands of rear mechs differ in that way?

Or something else?

Thanks for your perspective.

Dave, who was set off on this path by the "Campagnolo 11-speed shifter/derailleur compatibility chart" thread

[Mark McM]

Fortunately, Campagnolo publishes all their installation manuals on the "Documentation" portion of their web page:

https://www.campagnolo.com/US/en/Sup...#documentation


Here's the instructions for installing 12spd rear derailleurs:

https://www.campagnolo.com/media/fil..._07_21_ENG.pdf


Campagnolo has a different way of setting the derailleur limit screws. For the high limit screw, they specify that the upper jockey wheel should be aligned with the small sprocket. But for the low limit, they say that the screw should be turned out until the chain can be shifted to the large sprocket, and that derailleur cage should not contact the spokes.


Personally, I use Campagnolo's method for setting the low limit, and Shimano's method for setting the high limit. For the low limit, the derailleur should only be allowed to swing far enough to able to shift into the largest sprocket. But for the high limit, the derailleur return spring has the least force in this position, so if the derailleur hits the stop too early, it may not pull the chain all the way down. So I allow the derailleur a little extra freedom by aligning the derailleur pulleys just a scoosh to the outside of the small sprocket.

[DHallerman]

Mark, thank you much for this walk-through. In my mind's eye, the personal method you use (Campagnolo's method for setting the low limit, and Shimano's method for setting the high limit) sounds much like the standard Shimano method.

That is, the low limit places the pulley directly beneath the largest cog in either case, Shimano or Campy, so that the mech doesn't go into the spokes. And that "little extra freedom" Shimano-style by aligning the pulley just slightly to the outside of the small cog, even with Campy, makes much sense.

Typically, I set RD high and low limits without the chain being installed. Instead, viewing from behind, I simply push the derailleur to its two limits, in and out, observe the top pulley's position relative to the two end cogs, and adjust the limit screws as necessary. And only then do I install the chain.

Dave