Has anyone ever overhauled a set of these. I know lots hate them, I've had at least six good years out of this set and want to continue their life on my single speed. The front's pretty easy, just sealed cartridge bearings that i guess i should just completely replace, the back is kinda weird, non-drive side cartridge bearings, regular bearing setup on the drive side. Is there any kind of upgrade one can make to improve the quality, or are you stuck with spinergy b.s? Cartridges look like shimano. Any help? This is the first time I have taken these apart, they are pretty crunchy, but a testament to the product's life if they haven't been abused very much. Thanks.