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Originally Posted by
larsbb
Is it the hub or the sprocket that determines if the bike is a fixie, single speed or other?
A bit of all really.
”True” fixies require a hub with a threaded ”neck” around the wheel axle. This ”neck” should have two diameters, the smaller, outer one being reverse threaded to accept a locknut to hold the sprocket in place.
However, the thread for the sprocket is the same thread as for screw-on freewheels, which means that fixie hubs can be used together with screw-on freewheels. Easiest as SS bikes, but often also as derailer gear bikes by adding/moving axle spacers and resisting the wheel.
And of course there are/have been a few conversion kits, adapters and specials.
Used to be one where you took a Shimano (derailer gear) cassette hub and replaced the freehub body(in cassette hubs, the sprockets and the actual clutch mechanism are treated as separate pieces. The f/h body is what holds the clutch) with a solid piece which turned it into a kinda-sorta fixie hub.
then there are sprockets that bolts onto the brake rotor mounts to create a fixie wheel.
Originally Posted by
larsbb
I would think that it was the hub, so if I was wanting like a shimano xt hub, how would i know if it is single speed and fits the sprocket I have bought?
I’m not aware of any XT hubs made as SS from the start. AFAIK they’re all cassette hubs.
But you can buy a splined sprocket and a set of spacers to mount a SS sprocket to a stock XT hub with a minimum of fuss.
I believe Shimano has a line of bmx hubs, which would be SS hubs, and entirely possible to lace into the rim of your choice.
To know if a sprocket will fit a hub, check the specs of the mounting method, splined vs threaded.