Has anyone tryed using loose ceramic silicon nitride Si3N4 bearings. There seems to be a couple people selling them for hubs, crank BBs, and headsets. I figure this is a cheaper way to go then all new parts. I ask because I have a new RED crank and there is a difference over old bearings.

Anything makes a difference over old bearings. What alot of people seem to forget or refuse to accept is that Campagnolo (cant speak for Shimano) only used grade 100 loose balls through the late 80's. Yes, grade 100, that means that 'upgrading' to grade 25 is an improvement. Ceramic bearings primary beneifit for the C&V crowd is for those who may store their bikes after a wet ride. A vast majority of the dead BB's and axle cones I've seen have been from rusted bearing surfaces.

Ceramic bearings may or may not improve the function of C&V equiptment, seriously, whats the point of installing grade 5 bearings if they're rolling on no better than grade 100 cones and races? That beaing said, I have ceramic catrdges in my OLMO BB and ceramic loose balls in few of my bikes with loose ball hubs.

Ceramic bearings may or may not improve the function of C&V equiptment, seriously, whats the point of installing grade 5 bearings if they're rolling on no better than grade 100 cones and races?
I have changed the bearings on all the bikes I ride to grade 25 and the ones with good cups and cones work really well. Then my new bike I put on a RED crank with the ceramic BB and the differance is amazing. For the bikes you put loose ceramic bearings in did you see that kind of difference. At $1 per individual ball a BB would be $22, a great price if it makes the improvement that I'm hoping for. The bikes I'm interested in changing over have good cups and cones.