I currently own a 2003 Trek 2300 bicycle, which has Shimano Ultegra 9 speed components. Almost all of the drive train is original but, in the 6+ years I’ve owned the bike, I have put over 20K miles on it. The components are starting to show their age. Time for a replacement. Since the 9 speed Ultegra components are starting to get hard to find, I was thinking I should upgrade to 10 speed. There are no modifications to the frame, so that is not a limiting factor. The current setup has a triple crank but, on my last trip to California, I found I did not need the granny gear. It would save some weight, money and effort if I move back to a double.
Since I’m now talking about doing a complete overhaul of the drive train on my bike, I decided to revisit the crank length issue. On my previous bike, a 1987 Shwinn Prelude, I had a pair of 180mm cranks. This Trek has only 175mm cranks. This was my only disappointment in the bike, but considering what I was gaining, I though it was a small price to pay.
Why do I think I need a 180mm cranks? Well, I’m 6’4″ and and take a 36″ inseam in my pants. The Trek 2300 is, and the Shwinn Prelude was, a 63cm frame measured along the seat tube. With other bikes that I have owned I have run into problems with the bike just not fitting right, so I am very sensitive to the size of the bike. Can I stick with the 175mm crank? Yes, the Trek has proven that. I do feel that I’m not getting the full power out of it? No, I seem to be not quite as strong as I would have hoped.
Last Friday, I went down to my local bike shop and talked with the owner. He thought I was nuts on two accounts. The first thought he had was the cost of doing the complete overhaul. I had estimated the cost of parts to be over $1,000. The second though he had was that I would be best to stick with the 175mm cranks and to be spinning faster. I currently spin around 95 to 105 RPM when I’m out on the road; when I ride the trainer, I tend to grind it out since I want to work on leg strength.
So where does this leave me? I think I have more questions than I did in the past. Doing some research on the Internet, you find several different sites about crank length. Should I trust them? They sound good, but is it really just pop science behind their arguments? Here are some of the site’s I have found: