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local trails rider
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12,300 Posts
Discussion Starter · #1 ·
At least Turner, Transition and Banshee are going to start giving the "Reach" and "Stack" figures of their frames/bikes.

Reach = horizontal distance from BB to head tube - top tube joint
Stack = vertical distance from BB to head tube - top tube joint
http://bansheebikes.blogspot.com/2008/12/reach-and-stack-based-sizing.html

I think this should work. I'd mainly need to add
- seat tube angle (and length) that lets me put the seat where I need it
- BB height that is low enough but not too low
- head tube angle that gives good steering response
 

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local trails rider
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12,300 Posts
Discussion Starter · #3 ·
I have three bikes now:
Seat tubes range from 16 to 19 inches and I have no difficulties getting the seat high (or low) enough.

The longest horizontal top tube is 60.9cm and the shortest about 57cm. Those bikes have near identical riding positions, aided by different seat tube angles. "Reach" measurements are same, "Stack" measurements are close enough to handle with stem and bar arrangements.
 

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Premium Member
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48,238 Posts
perttime said:
At least Turner, Transition and Banshee are going to start giving the "Reach" and "Stack" figures of their frames/bikes.

Reach = horizontal distance from BB to head tube - top tube joint
Stack = vertical distance from BB to head tube - top tube joint
http://bansheebikes.blogspot.com/2008/12/reach-and-stack-based-sizing.html

I think this should work. I'd mainly need to add
- seat tube angle (and length) that lets me put the seat where I need it
- BB height that is low enough but not too low
- head tube angle that gives good steering response
It is a start. The "reach" is similar to what I have been calling "functional top tube length".
 

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Registered
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5,762 Posts


I think they should add a third number - BB to TT distance. So that it is independent from the choice of A2C of the fork and from sag. Obviously it is easy to compute it from stack and reach, but I think as a single number it is even more important as it is the only one that can be actually measured on the frame alone). That is pretty much the downtube length.
 

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Bicyclochondriac.
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15,210 Posts
perttime said:
At least Turner, Transition and Banshee are going to start giving the "Reach" and "Stack" figures of their frames/bikes.

Reach = horizontal distance from BB to head tube - top tube joint
Stack = vertical distance from BB to head tube - top tube joint
http://bansheebikes.blogspot.com/2008/12/reach-and-stack-based-sizing.html
This is great news, IMO. MUCH more useful than effective tt, as that is heavily effected by seat tube angle.
 

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No longer 26
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3,090 Posts
Great idea. The center of the bottom bracket is the best point to start the sizing/fit of a bike I'd say. I always have the handlebar and saddle measurements taken in relation to the bottom bracket written in the workshop so I can set up any bike to my "fit" quickly and easily.
G
 
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