# How do I "measure" my hub please?



## baker921 (Jul 20, 2007)

I know this is backwards but my freehub is toast in what is a fairly cheap no brand wheel possibly Rigida. Rather than chuck the whole wheel away I thought I'd like to try replacing the hub as much as anything for the experience. I know this isn't really cost effective so I want to re-use the old spokes therefore I need to get a hub with the same critical dimensions as the old one. Hence what do I measure and any tips in finding suitable matchers? Thanks for any help.


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## ergott (Feb 26, 2006)

I have vernier calipers with centering tips for flange diameter. I measure flange spacing with my Park TS-3. It has parallel arms unlike the TS-2. I can measure overall width, then measure dropout to outside of flange with standard vernier calipers. .5 Overall width - .5 flange width + dropout to flange and I get center to flange. This method is repeatable and easy to measure. I have the calculation in a spreadsheet so I just plug in numbers for speed.

-Eric


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## JCavilia (Sep 12, 2005)

Maybe you need some more basic facts, before you get to ergott's careful measuring techniques.

You need to determine 2 parameters: flange diameter (to the center of the spoke holes), and flange offset (or width) -- the distance from the hub center to the flange. For a rear hub the offsets for the two flanges will be different, with the right one closer to center.

If you get within a millimeter or two on each measurement, you can be pretty confident of being able to re-use the spokes. Diameter is the more critical measurement. An error of a given amount in the width measurement affects spoke length by a much smaller amount.


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## Mike T. (Feb 3, 2004)

You can find how to measure hubs here -

http://www.wheelpro.co.uk/spokecalc/

Click around.


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## baker921 (Jul 20, 2007)

Thanks everybody. Thats just what I needed to get started.


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## AndrwSwitch (May 28, 2009)

It sounds like you've got some good information.

I'm just posting to say that I did a hub swap on a front wheel last Fall, and it's been working fine since then. Stuck a $5 Shimano Parallax hub my mechanic had around in in place of the POS Formula loose-ball hub that the wheel came with. It's nice to at least start the season with everything on a bike working.


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## pitracon (Aug 29, 2006)

ergott said:


> I can measure overall width, then measure dropout to outside of flange with standard vernier calipers. .5 Overall width - .5 flange width + dropout to flange and I get center to flange.
> 
> -Eric


Hi Eric,
Probably I am missing something. Your formula should read

(0.5 Overall width) - ( 0.5 flange width ) MINUS! dropout to (outside) flange

instead?
So according to this, you consider flange distance as the measurement from OLD/2 to center of flange, correct? Other people, like Roger Musson advocate measuring from OLD/2 to inside of flange instead, just clarifying.

Many thanks for your answer and time.


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## TomH (Oct 6, 2008)

Center to flange is the way all the calculators ive used are setup. I like the DT swiss calc the best, and it requires center to flange and diameter.

I cheat and use CAD after a few quick measurements


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## ergott (Feb 26, 2006)

Using center to center of the flange is best in the spirit of accuracy. Truth is using center to outside or inside measurement will not change spoke length enough to make a significant difference.


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