I've got a 16-ish mile commute each way and I've done it on 3 of my 4 bikes:
1988 Trek 400 (dumpster salvage, converted singlespeed, rack/panniers)
2008 Surly X-Check (geared brevet bike, Carradice/Berthoud randonneuring luggage)
2011 Vassago Fisticuff (singlespeed monstercross racer, courier bag, no racks)
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"I feel like my world was classier before I found cyclocross."
- Mandi M.