Measurements - help please!

[psyclone1976]

Hi, how do i measure the top tub and frame size.

this is what i have been doing so far

Frame size - Middle of BB to top of seat tube?

Top tube - middle of seat tube (from where the top tube meets the seat tube) to middle of head tube?

Can someone let me know what it the correct way?

 

[Hilts]

The ways you describe are how I always do it...

 

[Max P]

The seat tube method is right. Top tube is not.

The way you do it will give you the actual top tube but nearly everyone these days uses the effective top tube measurement. The actual top tube is really only applicable to non sloping (generally road) frames.

So take a straight edge from the centre of the head tube/top tube junction and an imaginary horizontal line to the seat post centre.

There was a big topic on this a week or two ago.

 

[orange71]

some people like centre of BB to centre of top tube - sometimes gives you a better idea of the geometry. I tend to go by a combination of c-c and c-t - I like to know both.

 

[Max P]

As here:

http://www.calfeedesign.com/images/framemeasurepic1.gif

Road frames are a bit different as seat tubes tend to be done centre to centre. However, for modern road frames (compact ones) many people use an effective seat tube too.

Nearly all MTB's are c-t these days but Surly use centre to top of top tube not seat tube or centre of top tube...

 

[psyclone1976]

Cool thanks very helpful, trying to measure my GT Psyclone that will be up for sale here very soon.