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For actual track use, there's really no point in anything other than a disc. Six Day riders seem to like non-disc rear wheels, but nobody else does. Same goes for time trialling on fixed on normal courses; it needs to be either blowing a gale or going over mountains before anything else makes sense, and then you probably wouldn't be on fixed anyway. So my first question is: What do you want it for?

What about the front wheel? It's common to have a disc rear, but I don't see many fronts although they are readily available. Any reason to not use one for track racing?