Shutter Precision 8 Dynamo hubs are unrivalled in every sense of the word. They are more efficient, technologically advanced, simpler and lighter in weight than any competing hub dynamo by class. When lights are on, the P-8 Series (3W) and S-8 (3W for 20” and 2.4W for 700c) hub dynamos achieve an incomparable efficiency of 72 percent (i.e. watts of mechanical energy converted directly in watts of electrical energy – minus wasted muscular effort that would otherwise be propelling rider and bicycle forward).
The heart of the SP generator mechanism is a solid high-specification magnetic ring that rotates around copper coils as the wheel turns to produce electricity. This mechanical design is crucial as most modern hub dynamos rely on a number of magnets bonded onto the inside of the hub’s shell. When hub dynamos breakdown, it is often due to failure of the bonding adhesive holding the individual magnets in place – such breakdowns are more common in colder climates that accelerate deterioration of bonding adhesives. The design of SP hub dynamos makes this type of catastrophic failure virtually impossible.
Here is a positive review from Road.cc.
The Shutter Precision PD 8X dynamo hub would build up nicely with a wide alloy rim for daily riding or Audax use. Available in rim or disc brake configurations and now the Thru bolt version is available too.