Summerson's Guide to Climbing, California Edition

John Summerson's book, The Complete Guide to Climbing by Bike, is a wonderful reference to some of the best cycling climbs in the United States. But the US is obviously vast, and a national guide, while useful for planning trips, may be less useful than guides with a more regional focus. So he's started producing a regional series, as well.

First was a book on the Southwest. This is really good, but is mostly a subset of the national guide, with a few more climbs added in. Still recommended.

Far closer to home for me is the newly released California edition. Wow! What a resourse! If you ride in California, this is a must-buy. Even if you find one, just one climb here you weren't aware of, one gem of a climb to add to your "done that" list, the cost of the book is more than justified. And I can't imagine any rider not finding some inspiration here.

Okay, now to some details.

First, the route profiles... at first I was taken aback at the relatively low resolution of the profiles in the first book. In the CA book, the resolution has improved, but still these are below the level one can get from many sources, such as Lucas Pereira's gradiometer page, or from Strava. But the profiles work! The reason is for each segment, he posts the range of grades in that segment. How much information can one process, anyway? Basically you get the feel for the climb from John's representation, where from full profiles, it can be hard to grasp all the detail. So the profiles work for me.

Then there's his descriptions. Some of these are fantastic, really translating John's passion for climbing and ability to find a unique personality in each individual road. But some of the descriptions do fall a bit short, or are insufficient to navigate the road. For example, Mt Tamalpais in Marin or Lomas Cantadas in the Berkeley Hills both get short treatment. Lomas Cantadas in particular is quite a navigational challenge: we did it in the 2008 Low-Key Hillclimbs. But these are the exception: room for improvement in version 2. Most of the climbs are excellently described given the space limitations.

Then the climb numeric ratings. I love numeric ratings, and John's formula strikes a nice balance between simplicity and ease of calculation and accuracy. Now "accuracy" needs to be put in heavy quotes, as each rider has their own idea about how distance, altitude, grade, and steepness each contribute to how hard a climb is. So any formula, no matter how quantitatively precise, is going to have a heavy dose of subjective. I'll comment more on the formula in a bit, but first some background.

First there's the concept of "climb difficulty": gaining 1000 feet in 2 miles may be tough, yet may be less tough than gaining 1000 feet in 200 miles. Distance alone adds difficulty. A climb rating should be for only the "climbing" component. So the 2 mile climb is rated harder than the 200 mile climb, even if finishing the 200 mile climb is far more challenging.

Next a comment on the definition of a "climb". John described a definition in the first book, but liberalized it for the CA edition. And justifiably: Mount Hamilton was considered three separate climbs in the first guide due to the descents, but is included as a single climb in the CA version. I may comment more on this in a later post, but Hamilton is certainly a climb on its own, so I support the liberalized definition. Unfortunately the stricter definition is still listed on page 14 of the CA edition. He just fails to comply with it in the climb selections.

Then on the statistics: John derives elevation data from digital map data using measured GPS coordinates. Unfortunately, small errors in a GPS reading can result in large errors in altitude, so the numbers aren't always good. See, for example, a discussion of Motionbased Gravity, which applies this same technique.

One example is Old La Honda. The canonical number for Old La Honda out of Woodside is 1290 feet, which checks out with Google's "terrain" map. That's Lucas Pereira's number, for example. John has 1344 feet.

Kings Mountain Road is a bigger issue, where Lucas has 1540 feet, which also checks with Google. But John's number, 1691 feet, is clearly too high. John starts the "climb" at Highway 84, rather than at Greer Road or Entrance Way, with the segment between Highway 84 and Greer having negligible grade. So something's up: I'm not sure what. So if you really care, you might want to check altitude numbers against Google Maps.

Then there's the difficulty formula itself. He describes the formula as square root of grade multiplied by altitude difference (net, not gross) multiplied by an adjustment for peak altitude multiplied by an adjustment for the fraction of the road which is unpaved multiplied by a "bonus" if the road meets a certain criterion for non-uniform grade. All good, although I'd prefer the nonuniformity component be continuous rather than all-or-nothing, but I understand the need for simplicity. But then in the listed ratings, he uses the grade itself, rather than the square root of the grade. Obviously he decided the square root failed to give enough credit to truly steep climbs. But I feel square root works better for shallower grades. I may comment on the formula, and propose a compromise, in another post.

But altogether, I love this book. It's a great resource, one which I hope becomes available in every bike shop. Indeed, anyone getting into cycling should buy a copy. And everyone already into cycling should buy a copy, as well.