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Technical & Reference Section => Tech and Restoration => Topic started by: 20to26 on July 17, 2009, 02:09 PM

Title: headtube & headsets diameter sizes
Post by: 20to26 on July 17, 2009, 02:09 PM
I've noticed on some of my GT frames that some headset cups fit very loosely (like they're 1.1/8"...) and I need reducers to fit a 1" headset. Strangely I just removed a Hatta MX-II from one to fit an Epoch headset and I need reducers... :-\

anybody know what gives? Are there 1" headsets with different cup size diameters on the OS bikes?
Title: Re: headtube & headsets diameter sizes
Post by: thecrooch on July 17, 2009, 03:23 PM
it may be (and dont quote me on this) a road 1" headset - BMX headsets have a different size to road even though both are 1"

Chris King do an explanation that ill try and dig out in a mo....

here: http://www.aspirevelotech.com/Reference/CupSkirt.htm (http://www.aspirevelotech.com/Reference/CupSkirt.htm)
Title: Re: headtube & headsets diameter sizes
Post by: 20to26 on July 17, 2009, 04:13 PM
thanks for that Si, it seems odd that in this particular case I'm fitting a GT Epoch style headset into a GT BMX frame and it's not a snug fit. About 1mm out each side as the chart in the link shows. So perhaps GT made some narrower cup diameter headsets too for some reason.
Title: Re: headtube & headsets diameter sizes
Post by: thecrooch on July 17, 2009, 04:16 PM
Shim it with a coke can  - always works!
Title: Re: headtube & headsets diameter sizes
Post by: tobybrown35 on July 17, 2009, 07:05 PM
had same problem dans comp do a shim 7 dollars and about 40 dollars postage  :daumenhoch:
Title: Re: headtube & headsets diameter sizes
Post by: oldtired on July 17, 2009, 07:13 PM
brass sheet to make a shim,from hardware shop , comes in different guages so you can get it  a snug fit, couple o quid at the most for the amount you need, failing that

Shim it with a coke can  - always works!


+1 on that   :daumenhoch:
Title: Re: headtube & headsets diameter sizes
Post by: Gary72 on July 17, 2009, 11:40 PM
I have a odyssey pro headset, and it needs a shim for BMX. Only ended up using the locking nut as that fits the threaded part fine.  I think Crooch dug out the chris king thing when I asked this question.

Title: Re: headtube & headsets diameter sizes
Post by: Gary72 on July 17, 2009, 11:42 PM
http://www.radbmx.co.uk/forum/index.php'topic=62798.0

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