GEORGE SCHRECK

It is seat tube length, so you have to ask the top tube length.

It is more complicated than that though. Some bikes are measured to the center of the top tube and some are measured to the top of the seat tube. In addition, the bottom bracket can affect the real size of the frame, as a high bottom bracket can result in a larger bike even if the seat tube length seems like the correct length for you. A bottom bracket that is one CM higher than antoher bike can make a 56 seat tube equivalent to a 57 CM.

Also, sloping top tubes result in a short seat tube that is not indicative of the real size of the bike. As a result, you have to ask what the effective seat tube and top tube length is.

----Original Message----
From: Steve.Long@clark.wa.gov
Date: 12/06/2006 2:22 PM
To:
Subj: [OBRA Chat] Sizing question

Sizing question

I think I may be a little confused about bike sizing. When someone says I ride a 57cm, 58 cm bike, or if you look online at say Colorado Cyclist and you see a bike that says say 55 cm, is that referring to the top tube length or the seat tube length?

Steve Long
GIS Analyst
Clark County, WA
360-397-2092 ext 4421

Monty Hill

My understanding is the measurement typicalyl refers to seat tube length. With the top tube varying to a lesser extent. Meaning small bike have a larger top tube than seat tube and larger bikes have a smaller top tube than seat tube. The most typical size bike 54 or 55 usually have a top tube that is very similar, thus the confusion. There are variances in how the tubes are measured center to center or end to end.

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>>> "Long, Steve" 12/6/2006 2:22 pm >>>
I think I may be a little confused about bike sizing. When someone says
I ride a 57cm, 58 cm bike, or if you look online at say Colorado Cyclist
and you see a bike that says say 55 cm, is that referring to the top
tube length or the seat tube length?

Steve Long
GIS Analyst
Clark County, WA
360-397-2092 ext 4421

Long, Steve

I think I may be a little confused about bike sizing. When someone says
I ride a 57cm, 58 cm bike, or if you look online at say Colorado Cyclist
and you see a bike that says say 55 cm, is that referring to the top
tube length or the seat tube length?

Steve Long
GIS Analyst
Clark County, WA
360-397-2092 ext 4421