Double-C (300k) is a nice way to spend a Saturday. For any ride 100k and up I usually have my spare folding tire in my fix-it kit. It's an over-developed rando sense of self-support. The day you leave something behind is the day you'll need it.
I ride 23s or 25s on the track, rolled 28s on the road for a while, and I've recently moved up to 32s so I can hit more gravel trails and dirt roads.
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"I feel like my world was classier before I found cyclocross."
- Mandi M.