I have a cyclocomputer that includes % of grade. I've used it on my benchmark hill, Fargo St., in L.A. - about a 33% grade. My cyclocomputer dovetails with the listed city percentage.
In addition, someone actually measured, foot by foot, the slope of the hill, and found it was as claimed.
So I trust my cyclocomputer. I rarely trust what anyone claims, though, unless they've also gotten an official measurement or used their own 'puter.
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