TerraCycle idler torn down, cleaned and ready to rebuild with new bearings. The idler on both my trikes started acting up at about 1,500 to 2,000 miles. It starts as a soft rubbing noise that you can hear on those slow grinds up hills. Usually heard only on the power part of your stroke while pedaling. So you're listening to a rub...rub...rub...and so on. It drove me batty trying to figure out where the noise was coming from. I have come to find out that others have enjoyed the song of the idler but, just like me, it took awhile to figure it out. It's not an "in your face" kinda noise and can easily be ignored if you don't do a lot of climbing.
New stainless steel sealed bearings. I don't feel that ceramic bearings are worth the investment. It's makes more sense to me to replace the ABEC-7 stainless steel bearings every couple of thousand miles or less. An eight pack of bearings cost me only $14 on Ebay. You probably can find them for less if you're not as impatient as me. These bearings are not some high end single purpose bearings that TerraCycle makes. Basically they're just skateboard wheel bearings (thanks Scott for that bit of info). Make sure they're the right size for your idler and if you're going with stainless steel make sure they're rated at least ABEC-7.
Evidence of a bearing going bad. The cup holds two sealed bearings. I'm guessing the wear on the cup shouldn't be like the picture. This is after less then 2,000 miles. I do a lot of climbing (if you don't climb you don't get the satisfaction of getting to the top or the rush of the downhill run) so I probably ask more of my idlers then most trikers.
Bearings are at the heart of an idler. It's not rocket science to maintain them properly.