You should not have trouble getting a spoke of any length at any full-service bike shop. Many cut their own to length right there. And it should only cost a few dollars or less.
j
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Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
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SB forever