~ Auto Buzz ~: On Vestigial Gearing and Its Evolutionary Implications

Friday 24 June 2016

On Vestigial Gearing and Its Evolutionary Implications





How do you know when you've got gears you don't use or need? It's a tough call. Some might even say there is no such thing as "gears you don't need," especially when it comes to those low-low-low ones. If you can set up your bike with a sub-(sub)-1:1 gear, go for it! And even if you usually don't use them, you never know when they might come in handy, so better save them for a rainy day. I mean, who knows - you might go on a long trip where all the climbing comes at the end, when you are already right and truly exhausted. Or you could be called upon to rescue a cat from a tree.

Anyway, that has been my take on it at least. Which is why, even when I stopped relying on the biggest cogs in my SRAMpagnolo drivetrain on a regular basis, I kept them. Just in case!

...Until one day, I lost use of them completely. I am a little embarrassed to admit this, but hey - I never did claim to be fastidious when it came to bike maintenance. But anyhow, at some point my chain started skipping whenever I would try to get in the big cogs. Adjusting the derailleur didn't fix it, and it was that particular flavour of skipping, where I could tell the cable needed to be replaced. But I procrastinated. And procrastinated. And in the meanwhile I simply didn't use those 3 biggest cogs that were problematic. And hey - it was winter, so I didn't go on any long or overly hilly rides anyway. I would get the drivetrain fixed before spring came.

But spring came, and I procrastinated still. I started doing longer rides, steeper climbs, all with the malfunctioning drivetrain. In short, 4 months went by while I rode without the use of my lowest gears. And I didn't miss them.

Looking at my drivetrain one day, I realised I was essentially lugging around three "vestigial" cogs. And an unnecessarily long-armed derailleur that was installed specifically to accommodate them, into the bargain. Now: If I had managed to make do without them for this long, while doing rides incorporating the steepest climbs around, exactly what was I saving them for?

I examined the SRAM cassette to remind myself what gearing I was in fact using. To my surprise, the biggest three cogs were 36t, 32t and 28t. Whoa. That meant the biggest functional cog in the cassette was a 25t. So really I was using a 7-speed 11-25t cassette to do all those  climbs, except with a lot of extra weight attached to it. I believe the technical term for that is: Jayzus!

So... I don't know. I am not going to go as far as switching to a racing cassette. And I still believe in stashing some "just in case" gears. But I think that the 12-29t cassette I had on my original all-Campagnolo drivetrain will be quite sufficient in that respect.

As mentioned in the previous post, I am dismantling my roadbike to have the frame painted. And when I get the frame back, I am going to re-assemble it slightly differently. Namely, the bladed-spoke wheels (which I have already given away) will be replaced with something more crosswind-friendly. And while I'm at it, I also think I will go back to my original all-Campy (sorry: "Campag") drivetrain, with a standard "rear mech" and "sprockets," if you know what I mean. It's a little sad to have finally achieved a perfectly functional hybrid sub-1:1 drivetrain, only to get rid of it 3 years later. But hey: Use it or lose it. It's evolution, baby. (Now: if anyone local needs an X9 derailleur and a 11-36t cassette, give me a shout.)

Do you ever discover "vestigial" parts on your bicycle? I am curious what they are, and what you do about it!




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