Circlip retains sprocket
Fixed or free at the turn of this screw
After a long gestation, an example of SRAM’s novel Fixed/Free Torpedo hub has finally landed on the editorial desk. The idea is straightforward enough and will appeal instantly to anyone currently running a flipflop hub on a fixed wheel/gear machine; the hub switches between fixed wheel and freewheel modes at the turn (well, seven of them) of a screw.
The screw in question has a flat slot head and sits in the right-hand (drive side) end of the spindle. The hub has domed spindle nuts, presumably for safety, and in a nice touch both nuts have a small hole in the dome through which the screw can be reached.
As with SRAM’s basic hub gears, a sprocket with three lugs sits on a steel boss and is retained by a substantial circlip. This allows use with a fixed hub with no risk of the sprocket unscrewing.
Large flanges should ensure a sturdy wheel, while the overall construction looks well able to endure hard usage in arduous conditions. The bearings are not, however, sealed, but merely shielded in the manner of the T3 three-speed hub so no trying to ride through floods…
Turning the screw all the way out engages freewheel operation; turning it all the way in locks the freewheel and turns the hub into a fixed wheeler. Why would you want to do this? The trendy urbanite will probably conclude that simply being able to do it is justification enough, but the serious fixed wheel rider will appreciate the usefulness of being able to ride fixed in town or slippery conditions with the choice of a freewheel in hilly country. Assuming, that is, he or she has front and rear brakes…
This still leaves only one gear ratio, of course, where a flip-flop hub allows the choice of different ratios for fixed and free. Perhaps more important, especially in terms of the hub’s appeal to UK riders, will be the fact that it is offered with an Over Locknut Dimension of 130mm rather than the track (and, therefore, fixed) standard of 120mm. RCUK has already mentioned this to the manufacturer and it should not be too difficult to provide 5mm narrower hub cones if required…
UPDATE: We have been informed by SRAM that a 120mm OLD version will be available within a couple of months. Should be good.