Bicycle Sizing, Fitting, and Buying, Part I

I got an email yesterday that read:

Dave, I have a friend who wants to buy a bike. He is 5'-11", would a 26" bike be the right size for him? Thanks, DF

This is what I wrote back: DF, This is problematic and confusing. '26"' typically refers to the wheel/tire size used for most mountain bikes and some hybrids bike. Bikes with this size wheel are typically made with a range of frame sizes, which are typically specified in one of two ways: either by the length of the seat-tube, or by a generic SMLXL designation. Someone 5'-11" would typically ride a size "L" bike, or one with a seat tube between 18 and 22 inches. Here is a picture of how to measure the seat tube, but it's more complicated than it looks. Depending on where you take your measurements, results could vary by 6 inches. And even then there are too many variables to count. This type of confusion is all too common. I think it stems from the fact that we Norte Americanos think of bike riding as recreation, and something we did when we were kids. Kids bikes are sized by the wheel/tire size, starting with a so-called 8 or 12 inch wheel, and going up to 24" or 26". Actually, there are more wheel/tire sizes than you can count, and it's a topic of which I'm quite fond. This is a handy resource if you want to know more.

Buying on EBay or Craigslist

Here's the rub. In order to have a good used bike transaction, at least one of the parties has to know something about bikes, and be somewhat honest. It's clear from the size designation you gave me that the seller doesn't know his seat tube from his head tube, to coin a phrase. Since you're asking me, I'll guess that your friend isn't an expert either. The result, as far as I'm concerned, should be "No Sale." Sometimes friends send me craigslist or eBay postings to evaluate for value and fitting. It usually works out pretty well. If you want to get into it, this is the most reasonable article I've found on bicycle fitting, but it's not much help in this case, since the bike and the rider aren't right in front of you. This (Sheldon Brown's article on bike sizing) is also a good site about bike sizing, and all things bike. Bike fitting is like chocolate chip cookies: everyone has their own recipe and they think it is the best, and if you challenge it, then you're challenging the knowledge and expertise of challengee, his mentors and gurus, and all those who came before him, including his grandmother, from whom he got the recipe in the first place. Have a good night. Oh, thanks to Martin for being cool with me using a picture of his bad-a** Armageddon bike (that is, the bike you ride out of town on when the Armageddon comes).