Bike frames: Why “what size am I?” can be a tricky question

Our staffer Aaron came across this article in VeloNews about measurement standards for determining a bike’s frame size.

The article highlights an important question we hear from the majority of our customers: “What size am I?” – and the answer isn’t as straightforward as they often expect.

In the past 10 years, someone looking for a bike would probably refer to frame size as “XX cm.” This measurement referred more or less to the distance from the center of the pedal crank to the frame’s top tube. A 6’0″ man would probably know, “I ride a 58 cm”; a 5’6″ woman would probably say “I ride a 52 cm.”

Stack and Reach chart - Dan Empfield

Stack and Reach chart - by Dan Empfield

But bike design has evolved, and traditional sizing terms can sometimes be more of a range (“I’m about a 58cm”) than a standard.

Some factors: For example, the distance between the crank and top tube does not account for sloping on tubes within the frame, nor does it account for the reach from bike saddle to handlebars. All of these variables effect the overall fit of the ride, creating variations that no longer depict traditional size.

Accordingly, of course many people are confused. The specs can get quite complicated!

Ultimately, as with all products, bikes design and terminology will always be evolving. The new terms in the article proposed using two numbers, essentially frame height and frame reach distance. So, height/reach, or XX/XX. It doesn’t fix everything, but offers some reasonable considerations.

We don’t expect our customers to be experts; our team is trained to provide the best expertise in bike size and fitting, even as specific as adjusting for headset, stem length, pedal setting and saddle placement. But we like the conversation that Dan Empfield and team are leading around improving not just bike frame design but also the terminology for frame sizes.



About bicyclehabitat

New York City's neighborhood bike store since 1978
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