Italian manufacturer Extralite's SPX rear hub is the grandfather of their ultra lightweight SX hub series. The main difference between this and the others is that this SPX features straight pull spokes on both left and right sides which results in an increased bracing angle and an arguably more durable spoke. At 133 grams this is their lightest rear hub.
The Ultrarear SPX is one of the lightest rear road hubs available, with a design that promises performance on par with much heavier models. A tool-free micro adjuster allows for optimum bearing preload, while the high quality steel cartridge bearings are optimized for low drag.
Extralite's SX, SLX, and SPX hubs utilize interchangeable axle ends for Campagnolo and Shimano compatibility. This allows for the best possible spoke bracing angles for maximum lateral stiffness.
As with all Extralite products, UltraHubs exceed the European UNI/DIN Safety standards. Extralite's safety tests simulate a very strong 90kg (200lb) rider output.
We recommend that Extralite hubs, especially the SPX be built by an experienced wheelbuilder. We are happy to provide this service, and can provide helpful suggestions in rim and spoke selections. Please contact us directly or submit a form for a custom wheelbuild here.
Extralite hubs feature carefully designed rubber o-ring seals and lightweight ratcheting mechanisms which require frequent service to ensure long life and maximum performance. This service is easily performed with simple hand tools. An instruction manual for UltraRear 2.0 hubs is provided here:http://www.extralite.com/Manuals/UltraRear%20SLX%20Version%202.pdf
Extralite strongly recommends the use of their Alugrease Super 1 when lubricating the UltraRear's o-rings, bushings, and drive rings.