Hand built carbon wheels are better. Machine built wheels fall short on the final finishing touches. High speed productivity is the hallmark of machine built wheels.
Hand built carbon wheels produced by a skilled technician are finished with a high degree of attention to detail. It takes skill and patience to fine tune the spoke tensions and stress relieve the wheel. Any short cuts here result in a wheel that goes out of true after a few rides.
Most factory wheels are left low on spoke tension in the hast to improve productivity. An under tensioned wheel results in cyclic fatigue and shortly thereafter to broken spokes. It is the under tensioned spoke which fails first. A properly built and tensioned wheel will rarely break spokes.
The combined process of trueing, tension balancing and stress relieving a wheel takes time. It takes a dedicated technician to put in this effort for the client. The result is a high quality, long lasting wheel set; and a very happy client.
