Stems and sizes - what´s the norm

[MyiataTRR]

So I´m looking for a stem for a little project. The steerer outer/headset is 1 1/8", hence I need a stem with a 1" diameter. As I understand it the stem is usually 1/8" smaller then the headset. What I find troubling is locating a proper size stem, as there seems to be no one way to nominate the size.

So what is the usual norm? Giving the headset size and I have to detract the 1/8, giving the actual stem diameter? Or both? Looking on the ´Bay I find all different descriptions, and if not specified, I´m not really sure what size it is.

Also, if anyone got black, 10 - 30 degree, 100 - 130 mm reach, 1" diameter (to fit with a 1 1/8" headset...see, I´m confusing myself now), PM me

 

[jax13]

assuming i was explaining it to the missus........

basically - you have 1" headsets and a 1 1/8" headsets (i know there is 1 1/4 too but lets keep it simple!)

a 1" headset needs a 1" stem and 1 1/8 needs 1 1/8. they are named for the headset size rather than the steerer size otherwise 1" stems would be classed as 22.2 (i think) and 1 1/8 would be 25.4mm.

there is also the threaded / non threaded side of things where you will either need a quill stem or an ahead stem depending on the type. adaptors can be used to go from a quill to an ahead safely although they don't always look like the neatest conversions.

so..... if you have a 1 1/8" headset and the forks are loose fitting rather than held being held on by the top of the headset screwing down onto the steerer holding them in place - you need a 1 1/8" ahead stem. if your headset is screwed onto the steerer at the top you need a 1 1/8" quill.

hope thats clear enough!!

 

[one-eyed_jim]

It's a bit of a minefield. Have a read of this:

http://www.retrobike.co.uk/forum/viewtopic.php?t=131126

In summary, it's more common to specify the physical quill diameter in millimetres, and the nominal headset size in inches. Not all eBay sellers are aware of that however, so be prepared to double check.

 

[MyiataTRR]

Thanks, pretty much as I thought then, and as always the answer is double check