If you're the sort of fan who's impressed by outsized chainrings, the Doc's got some killjoy science to grind your gears
A few years back I went for a ride with former pro Sean Yates. It was a ride notable for the unceasing rain, and for a voice in my head telling me that if you’re riding with a top-10 Paris-Roubaix finisher, you don’t complain about the rain.
On a smallish, steepish hill, he dropped to the small chainring. This surprised me; not a fortnight earlier I’d read that Sean had never used the small chainring in the UK, because the hills weren’t big enough.
“Small chainring, Sean?” I asked.
“ Yes,” he said.
“I thought you didn’t use that in the UK?” “It’s a 52 .”
Sean’s small chainring was, indeed, a 52 tooth. His big one was something like a 58t. I don’t really k now why he was running this set-up on his winter bike, and I didn’t ask, because I felt as small as my teeny-tiny 39t.
doctorhutch.cycling@futurenet.com
I have told this story many, many times since. Invariably it’s greeted with a gasp. A 52-tooth chainring… on the inside?
It’s true that since the dawn of time, a measure of a bike rider has been the size of their chainring. We’ve called them “dinner plates”, we’ve called them “windmills”. And when Tobias Foss rolled into time trial action at the UAE Tour last week armed with a 68t, the internet of cyclists went very gooey indeed.
It wasn’t just that. A few days earlier I saw a time trial televised with on-screen graphics that showed how big everyone’s chainring was. The commentator told us that the winner had won because he had the biggest chainring.
Before we lose our collective minds, a little maths. The size of your chainring makes less difference than you think to the actual gear ratio. Yes, I k now, this is going to be boring, but it will give you the tools to bore others in your turn, and together we can make a febrile world a little calmer.
If you had a fairly stock 52t chainring, and you exchanged it for a 60t, your gear ratio would increase by the equivalent of about two sprocket teeth. Now, on the club run, if you clunk a couple of sprockets further out the cassette, do people immediately celebrate your athleticism? They do not. Even the Foss-monster’s mighty 68t only shifts bet ween three and four sprocket teeth, depending a little what gear you started in.
The best technical justification for the big ring is a small gain in mechanical efficiency – running the chain around bigger corners in the drivetrain reduces the friction losses. So that guy with the big ring? He’s actually trying to make life easier for himself, the slacker.
At the last Olympics the GB team ran chains with 10mm pitch rather than conventi
