I'm having my LBS drop a 13-26 cassette on my resto project to replace the 11-21 stock cassette. Even so, I'm sure that with the 39/53 front, there will be some hills I encounter which will have me pushing the bike.
No shame in walking it. Just come back and keep attacking the hill over and over until one day you can ride all the way up.
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"I feel like my world was classier before I found cyclocross."
- Mandi M.