After many, many years of riding and many, many hours of constant, relentless -- nay, obsessive -- futzing with my bikes, I like to think that I'm pretty sensitive to bike setup. You scoot my saddle forward a few millimeters, I'm gonna know it. Drop my handlebars by the width of one skinny spacer, I'll figure it out. I'm the Rain Man of contact points: "Yeah, this is definitely not my saddle height. Definitely. K-Mart bikes suck."
Or at least I thought so. See, the two-seater in our fleet has been suffering some bottom bracket maladies lately, so I needed to pull the crankarms to get an accurate spindle length measurement for a replacement. In doing so, I also wanted to check the model number on the crankarm to make sure I was getting the right bottom bracket (it's the now-obsolete Octalink, and those came in two flavors). But what's this? A 170mm non-drive/timing side arm on the front end and a 175mm in the back? Cue confused Scooby Doo noise.
So I checked the drive side: 175mm on the front end, 170 on the back. In other words, the timing cranks had been mixed up. Now in all the times I've pulled the cranks on this bike, I've left the pedals on, and my stoker rides toeclips while I ride clipless -- which is to say that the chances are slim-to-none that I was the one who swapped the arms. I'm guessing it came straight from the Cannondale factory that way. Or maybe it was put together at the shop that way -- I don't know how much assembly was done at the factory and how much was left for the dealer on tandems. Either way, big oops.
That means that for almost ten years and countless thousands of miles, I've been riding a 175 on my right side and a 170 on my left, while Carla's been turning a 170 on the right and a 175 on the left. Never noticed. Neither of us suspected a thing. And now that I've swapped them back to their rightful locations? Can't tell the difference. Not even a placebo effect.
If there's a moral to this story, I don't know what it is. But I can tell you that the next time I feel the urge to stop mid-ride and move my saddle up or down a fraction of a millimeter, I think I'll just tell myself to get over it.