SURLY's classic Ultra New Hub is very similar to its predecessor. In fact, the hub shell hasn't changed at all. Made of machined aluminum based on 6061-T6 forging with mid-sized flanges.
So what's different is that the Ultra New Hub has been changed to a hollow axle that uses a uniquely designed thread-in-wheel fixing bolt instead of the previous axle with hub nuts. This hollow axle makes conversion to quick releases very easy (bolt removal, QR skewer insertion, wheel attachment to frame or fork, etc.). All Ultra New Hubs come with fixing bolts, but are QR compatible without the need for axle conversions or other extra optional products. The axle is made of chromoly steel, and the fixing bolt is made of 10.9 stainless steel because of its corrosion resistance, high strength, and good appearance. It can be tightened and loosened with a 6mm hex wrench.
The bolt caps and "cone" nuts are also made of stainless steel and have washers cut to firmly engage the frame. Doing so will reduce the chance of the wheel slipping into the frame under heavy load. The cone and dust cap work together to maintain the rigidity of the axle. The Ultra New Hub incorporates an adjustment-free industrial bearing 6901 model.
Another very important thing is that all the hardware used in all Ultra New Hubs can be converted to older New Hubs and they are sold in kits.
* This is the product page of FIX & FREE rear hubs and regular front hubs.