Difference of bottom bracket cup materials: resin, plastic, metal Bottom bracket cups are made of different materials. What are the pros and cons of the materials? What experiences do you have with them?


The metal could be problematic due to galvanic corrosion
Plastic might get brittle by time due to light, heat and dirt


This is my experience from other domains, though I don't have experience with resin.

E.g. for plastic I can think of pro = easy to remove by sawing and breaking it out if it's stuck and con = getting brittle due to to the environment. One more pro might be that it breaks by too much torque instead of ruining the threads. On the other hand, when I broke it this way, it causes more headache to remove the remainder. :)
You have the pros and cons pretty much down. I'll add a couple:


Metal cups are stiffer.
Plastic/resin cups are less expensive.


I am not familiar with resin, but I would suppose it has similar characteristics to plastic.

From what I've seen, all the higher-end bbs use metal. Probably meaning that the only reason plastic is used is to reduce costs.

As a competent mechanic who has changed many bbs, I would favor metal. I'm not worried about cross-threading, and greasing the threads removes the potential for corrosion.