A roller bearing, comprising; a. a hollow, cylindrical outer race with a midline axis (120; 120') and inward facing, non-helical grooves; and b. a plurality of rollers axially aligned inside said outer race, said rollers being axially aligned and evenly spaced apart from said midline axis (120; 120') of said outer race, each said roller includes a plurality of non-helical teeth that mesh with said grooves on said outer race; characterized in the that the roller bearing further comprises c. two inner race pieces (45, 50; 45', 50') axially aligned with said outer race and inward from said rollers, each said race piece (45, 50; 45', 50') includes a plurality of grooves (47, 52; 47', 52') that mesh with said teeth on said rollers, said race pieces (45, 50; 45', 50') being separated by a gap (65; 65') with a desired width allowing said inner race pieces (45, 50; 45', 50') to move longitudinally together or apart to adjust the clearance between said grooves (47, 52; 47', 52') on said inner race pieces (45, 50; 45', 50') and said teeth on said rollers when assembled, each said inner race pieces (45, 50; 45', 50') includes a shaft bore and. d. a shim (70; 70') disposed inside said gap (65; 65') located between said inner race pieces (45, 50; 45', 50'), said shim (70; 70') having a width that is wider than the gap (65; 65') and thereby forcing said inner race pieces (45, 50; 45', 50') longitudinally apart and against said rollers to reduce the clearance or pre-load of said roller bearing; or to move said inner race pieces (45, 50; 45', 50') axially to allow a pre-load force to be applied to said roller bearing after placement on a shaft; or said shim having a width that is smaller than the gap (65; 65') and thereby allowing said inner race pieces (45, 50; 45', 50') to move. a. a hollow, cylindrical outer race with a midline axis (120; 120') and inward facing, non-helical grooves; and b. a plurality of rollers axially aligned inside said outer race, said rollers being axially aligned and evenly spaced apart from said midline axis (120; 120') of said outer race, each said roller includes a plurality of non-helical teeth that mesh with said grooves on said outer race; characterized in the that the roller bearing further comprises c. two inner race pieces (45, 50; 45', 50') axially aligned with said outer race and inward from said rollers, each said race piece (45, 50; 45', 50') includes a plurality of grooves (47, 52; 47', 52') that mesh with said teeth on said rollers, said race pieces (45, 50; 45', 50') being separated by a gap (65; 65') with a desired width allowing said inner race pieces (45, 50; 45', 50') to move longitudinally together or apart to adjust the clearance between said grooves (47, 52; 47', 52') on said inner race pieces (45, 50; 45', 50') and said teeth on said rollers when assembled, each said inner race pieces (45, 50; 45', 50') includes a shaft bore and. d. a shim (70; 70') disposed inside said gap (65; 65') located between said inner race pieces (45, 50; 45', 50'), said shim (70; 70') having a width that is wider than the gap (65; 65') and thereby forcing said inner race pieces (45, 50; 45', 50') longitudinally apart and against said rollers to reduce the clearance or pre-load of said roller bearing; or to move said inner race pieces (45, 50; 45', 50') axially to allow a pre-load force to be applied to said roller bearing after placement on a shaft; or said shim having a width that is smaller than the gap (65; 65') and thereby allowing said inner race pieces (45, 50; 45', 50') to move.