I'm no expert on the subject, that's for sure. Being a mechanical engineer, it just makes sense to me that the job of carrying axial loads would be better served by TR bearings. All that being said, the bottom line is I can't find any such TR bearings to replace the balls, so........ I'll just clean,pack,adjust for minimal side play and run. The old bearings will probably be just fine unless I do something stupid like use big fat tires and run the slalom course. Thanks for the input though!!!!