Bicycle Mechanics - Bike Sizes?? what to they mean?

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CourtAzukiRacer
11-19-07, 06:05 PM
I have seen a lot of people talking about bikes and relate to sizes.
example:
57CM MENS SCHWINN BLACK ROAD BIKE.. 32 1/2 INCHES TO CLEAR THE TOP BAR..
etc...
Im 6'2 and have an Azuki Racer and an 84 Murray. When I ride them I do feel small on them. What size would fit me??
CaptainCool
11-19-07, 06:28 PM
Frame size is usually center of bottom bracket to center of top tube. It's sometimes quoted as c-c, while c-t would be center of bottom bracket to top of top tube.
Standover, the other number you have, is ground to center of top tube. For safety, keep it a bit lower than your true inseam (not pants inseam).
For your size, get fitted at a bike shop, or feed some measurements into: http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO
orange leader
11-19-07, 09:32 PM
To add to the Captain's response, The center to center measurement is also often abbreviated as c-t-c or ctc. and this is the frame size.
There is also a top tube measurement which will effect fit, which is usually measured c-t-c as well. That one helps people figure out if the top tube's length will match their torso and arm length.
Road bikes are generally measured in centimeters. Mountain bikes are generally listed in inches.
And to make it more confusing (I'm a big believer in full disclosure) there are frames out there that use "effective" sizes where they drop the top tube or slope it so you have more stand-over clearance, but the frame will feel the same (seat will position itself the same as) a frame with the "effective size" listed.
Keep in mind that a bike's fit can be changed by raising/lowering the seat, and/or changing the stem to a longer or shorter one as you need.
If you're 6'2" and are planning to ride a road bike, you'll probably want a 58 to 60 cm bike (seat tube length, ctc). Top tubes for road bikes are traditionally the same length as the seat tube, but sometimes are a bit longer or shorter, and if you can find one that suites your body type that's great (long legs, short torso go with a longer seat tube and shorter top tube). These differences can affect the ride quality too.
If you're 6'2 and looking for a mtn bike, you're probably looking for a 19-21" frame.
As the captain said, it's best to go to a shop and get fitted for a proper ride. Many shops have adjustable stationary bikes that will tell you exactly what frame measurements will make you the most comfortable, and give you the most power from your pedal stroke. They usually charge a fee, but will often credit you that amount towards the purchase of a bike at their shop.
Sheldon Brown
11-19-07, 09:39 PM
I have seen a lot of people talking about bikes and relate to sizes.
example:
57CM MENS SCHWINN BLACK ROAD BIKE.. 32 1/2 INCHES TO CLEAR THE TOP BAR..
etc...
Im 6'2 and have an Azuki Racer and an 84 Murray. When I ride them I do feel small on them. What size would fit me??
See: http://sheldonbrown.com/frame-sizing
Sheldon "Top Tube" Brown
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