Technical & Reference Section > Tech and Restoration

Stem Shims

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duncan:
I'd like to run a BMX stem and bars on my Mountainbike. It has 1" threaded forks, but the inside diameter is just too big for a close fit.

The original Mountainbike stem quill diameter (and inside fork steerer diameter) is 22.2mm, but my BMX stem is 21.1mm
Is there anywhere I can buy a shim/adapter to fit into the forks?

It does tighten up as it is, but not sure I'd trust it over any rough ground, plus there's a little side-to-side bend given the extra millimetre between quill and steerer.
Has anyone successfully tried this before using their own solution (cut up coke can etc)?
I know I could buy a Profile Boa stem which was designed for this very purpose, but I'd like to use my old Redline Forklifter if possible.

Thanks.

oberonspacefruit:
 i reckon the coke can thing would be fine. its alloy so it wont rust. i doubt if you would get a shim. though you can get shims for seatposts, see what sizes they do in those....

theRuler:
use some thin metal - the coke can sounds best

a shim with a 0.45mm wall would be pretty delicate so i doubt you can buy them

duncan:
Thanks for the replies,

Something that confuses me is that many webpages call a 22.2mm stem a 1" stem.
1" = 25.4mm, they're obviously referring to the 1" fork size, but it makes hunting for the right sized shim very confusing.

Is a shim sized by the stem it fits onto, or the outer diameter of the forks it fits into?
As they're split and can expand, I suppose it doesn't matter as long as it can fill up the extra 1.1mm space.

I did find this: http://www.billys.co.uk/english/group.php?prod=smid-quillshim
It's a convertor sleeve for 1"quill to fit 1 1/8" Steerer, not quite the right size but I'll keep looking.
I think I'd need something like a 15/16" to 1" shim.

I'll give the coke can method a try if I don't find something soon.

duncan:
This is the one I need, made by Wald, model number LLC #905:
http://www.bikepartsusa.com/product_info.asp?f_c=Seat+post&f_c2=shim&cp=2&p=01%2D127648

It's a seatpost shim, that converts 13/16" to 7/8".
Just so happens it can also be used to convert 21.1mm to 22.2mm for a stem!

No international shipping there, but I have located it elsewhere.

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