We generally have all sizes, from 13 to 22 tooth, of fixed sprockets in stock
in 3/32" (normal narrow derailer chain),
as well as the older style 1/8" sprockets, but we don't recommend the 1/8" width for new conversions. If you don't specify a width in your order,
we'll ship 3/32".
We used to carry less expensive sprockets from Esjot and Cyclo, but we had so much trouble with the cheapos that we've stopped carrying them.
In terms of quality, Phil Wood is the best, E.A.I. is second best, with Shimano Dura-Ace and Rockwerks/Surly tied for 3rd place.
These sprockets permit you to have two different fixed gear ratios, which can be selected without needing to remove the wheel from the frame, as with a flip-flop hub.
If you use them with a single chainring, you will need to be able to move the axle 1/8" per tooth difference when switching position. Chainline will be somewhat compromised.
If you use them with a double chainring with a the same tooth difference, you will be able to change gears without moving the wheel, and will be able to have perfect chainline.
For "9-speed" chain.
17 + 19
Teeth | Axle movement 1/4" | FCY251 $45.95 
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17 + 20
Teeth | Axle movement 3/8" | FCY252 $45.95 |
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17 + 21
Teeth | Axle movement 1/2" | FCY253 $45.95 |
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