Ceramic Oversize Pulley

[RoadRacer2020]

Hello guys, still novice here.

Just want to ask what's the purpose of upgrading your pulley to an oversize one?

And if you have any suggestions, please drop it. My bike is equipped with Shimano 105 r7000 groupset.

Thankksssss

[Jesper]

(07-13-2020, 11:07 PM)RoadRacer2020 Wrote:  Hello guys, still novice here.

Just want to ask what's the purpose of upgrading your pulley to an oversize one?

And if you have any suggestions, please drop it. My bike is equipped with Shimano 105 r7000 groupset.

Thankksssss

Hi "RR",

From what I know they are supposed to be more efficient concerning loss of wattage through the pulley cage "corrected" by: straighter chain angle (link to link), reduced pulley speed, lower bearing friction; but there may be increased areodynamic loss (possibly negligible), and higher weight. It might depend on your use; I think I'd like trying it on a touring set-up, or run a smaller pulley (11-13T) on the upper. Still might require experimenting with different rear clusters to see how well it feels when shifting, but for the price it does not appeal to me. Since I still run 9-10T on many older bikes, by using high tolerance ceramic bearing 13T pulleys serves nearly the same function at a fraction of the cost.
I would assume it helps reduce some chain slack if you were a little loose; but you may have to get a longer chain! This is starting to get expensive; glad I have old adjusting dropouts with ample room to add slack when using a larger pulley derailleur.