Ode to gear inches

The late Sheldon Brown’s web site is still THE resource for understanding the mystery that is gear inches (as well as a lot of other bicycle-related facts). What are gear inches ? It’s a fancy way of figuring how much a given combination of a bicycle crank ring and a cassette will move you with a full turn of the pedals. (I am really simplifying!).

Shimano Dura-Ace 10-speed cassette

Why would I care ? Well because I have a bike race on Sunday and the last time I was out riding in a group with a tail wind, I couldn’t mash the pedals fast enough, even at 125 rpm, to keep up. I was using a cassette with between 12 teeth and 25 teeth. I have another one, a much friendlier one for flat land, with between 11 and 23 teeth. I wanted to know if the difference between was significant enough for me to want to unmount the wheel, pull out my chainwhip and other tools, and change cassettes.

Sheldon Brown’s gear calculator told me that I would be about 10% better off with the smaller, more aggressive cassette, in the toughest gear.

The first chart is the easier of the two cassettes:

Gear inches for Shimano 12-25 cassette
Gear inches for Shimano 11-23 cassette

That being said, the question is more along the lines of how often I expect to be riding in the highest gear. Since this is not a time trial, but a more bursty road race, it may not make as much sense. More likely than note, I will be riding in the middle of the cassette, as per usual. And this is a hilly course, so the extra easier gear at the end (25 teeth instead of 23) will be appreciated.

I still have most of the evening to think about this. So I’ll give it some more thought.

I’m a sucker for gamification

I am currently in that awkward period known as ‘between marathons’ and so I have to fill the time. This time of year that usually means cycling, though I added an opportunity to be a pace bunny at a marathon in early June and complete marathon #20 in six years, so I have been running lately as well.

I use a Strava a quite a bit and have been a member since October 2010, soon after the service launched.

At some point, Strava launched a challenges feature and I have been hooked ever since. When it comes to riding, challenges include how much you climb (metres), how long you can ride (in metres), or how often you can ride (hours). As for running, challenges are often how much you can run in a month, as well as running a 10km or a half-marathon distance in a given month.

Needless to say, I often find myself putting in that extra 10-20% effort for the sake of a digital badge that goes in a digital trophy cabinet. It’s crazy but it works. I am Exhibit A when it comes to the effects of gamification, at least when it comes to physical activity. (I have no issues resisting the allures of casinos or gambling.)

This month’s challenge for cycling is to climb 6000 metres in the month of May. And so I have been making a point of seeking out hills and mountains to climb, instead of the typical flat in the Saint-Lawrence River Valley. After 1120+ metres on Monday night, I added another 720m this evening after work. Now sitting at 4816m, with a bike race this Sunday that will get me at least another 1700m, putting me over the top. My reward for all of this effort: in addition to a digital badge, I have the opportunity to buy a smoking hot pink — in honour of the Giro d’Italia— cycling jersey from Cuore of Switzerland. I have a few of their Strava challenge jerseys already and the materials and tailoring are wonderful.

Here is the jersey:


Here is tonight’s outing that got me to 80% of the way there.

Tomorrow night is all about running. There is a Strava Challenge—200 km in a month—for that too. 😉