Tuesday, January 23, 2018

How to choose the right bike frame size

There are plenty of ways to size a bike frame to yourself.  Notice I said 'size a bike frame to you', not the other way around.  When you purchase a bike, the bike should be custom fitted to you, not the other way around.  One of the best websites I've seen on how to fit a bike frame to you, is the Fit Calculator on Competitive Cyclist website: www.competitivecyclist.com 

You'll need a tape measure, stool, a bubble level and someone to take the measurements.
You'll need to take 8 measurements.  What's nice about the Competitive Cyclist Fit Calculator is that is shows you how to correctly take the measurements with both a photo and a video.  It doesn't get any easier/better than that.  You can take your measurements in either inches or centimeters.  I'd take it in inches since most tape measures are in inches. 

Here are the 8 measurements you need to take (I've included my measurements):

Inseam- 32"
Trunk- 24"
Forearm- 13"
Arm- 27"
Thigh- 23"
Lower Leg- 23"
Sternal Notch- 58"
Total Height- 71"

After taking my measurements, I entered them into Competitive Cyclists Fit Calculator.  Competitive Cyclist gave me 3 different results (for 3 different fits): a Competitive Fit (for aggressive riders or racers looking for speed over comfort), an Eddy Fit (less saddle to handlebar drop for more comfort), and the French Fit (puts you in a more upright riding position for maximum comfort and the largest frame).  Out of curiosity, I included the measurements from my Trek Madone 5.2 road bike (which is the same bike Lance Armstrong used to ride- so it's a race bike).  I was dumbfounded by the results.  It seems like my Trek Madone is a combination of all 3 fits..ha.  (see yellow highlights)  Go figure.

BTW, Trek recommends frame sizing from height alone.  According to the Trek sizing chart, I could ride either a 56cm or a 58cm size frame.  Since I'm 5'11" tall, I'm in the middle.  Too bad they don't sell a 57cm size frame.  I believe I opted for the 58cm size frame.  Perhaps that's why my bike measurements span all three of Competitive Cyclists Fits.  Now I'm wondering if my seat/saddle height is a little too low (BB Saddle position).  That would definitely put me in a more aero position when I'm in the drops.  Also seems like I can move my seat up a tad, which would decrease my saddle setback.  I'm not doing anything right now, because I'm comfortable when I ride and seem to be producing optimum power...for an old guy.

Power ON!  Coach Rob

No comments: