Abstract: A device for making micro adjusting a steering bearing of a head bowl of a bicycle head tube includes an inner ring of the steering bearing, a pressing ring and a clamping ring, which are mounted sequentially together in an upper end of the bicycle head tube. An upper end of the clamping ring is fastened with a handlebar upright tube of the bicycle, wherein the clamping ring provides a pair of lugs, each lug having a threaded hole for engaging with a fastening means, the clamping ring is provided with an inner circumferential tapered surface. The inner ring of the steering bearing is provided with an inner circumferential tapered surface. The pressing ring is provided with an upper outer circumferential tapered surface and a lower outer circumferential tapered surface. The upper outer circumferential tapered surface of the pressing ring is engaged with the inner circumferential surface of the clamping ring.

Abstract: An adjusting device assembly for making, a manual adjustment of a bicycle head bowl bearing comprises a front fork upright tube inserted into a head tube in which a bearing bowl is received. A bearing is received in the bearing bowl and can be located securely by an inner ring, which can be forced to move downwards by a locating ring which is in turn caused to move downwards by a clamping ring capable of being caused to move downwards by an adjustment bolt which can be fastened manually.