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Stem sizes

dan1983dan1983 Posts: 314
edited June 2008 in MTB buying advice
I'm wanting to buy a new stem but I'm unsure about all the different size options.

If something says:

90mm 8 deg 1.1/8" 31.8

What are all the numbers? I'm assuming 90mm would be length, and 8 deg the rise on it. But what about the other two? :?



  • z000mz000m Posts: 544
    31.8 is thickness of the handlebar clamp, 8 deg is the rise.

    i have a RaceFace Evolve XC II Stem 100mm length, 31.8, 6 deg rise
    its like new, i only want £15 for it. they cost £30 on crc

    pm me if ur interested
  • BlackSpurBlackSpur Posts: 4,228
    1 1/8" is the size of the steerer tube (the bit that comes out of the top of the fork that the stem clamps to).
    "Melancholy is incompatible with bicycling." ~James E. Starrs
  • dan1983dan1983 Posts: 314
    z000m - cheers, but I've seen the one I want.

    blackspur - thought it would be but wasn't sure, thanks for help.
  • dan1983dan1983 Posts: 314
    This is going to sound daft, but how do I measure them??

    1.1/8" seems tiny??

    and 31.8 (i'm assuming mm) also seems tiny.

    or am i just being thick?? :oops:
  • OllyUKOllyUK Posts: 230
    dan1983 wrote:
    This is going to sound daft, but how do I measure them??

    1.1/8" seems tiny??

    and 31.8 (i'm assuming mm) also seems tiny.

    or am i just being thick?? :oops:

    1.1/8" is the steerer tube diameter, it is the industry standard on most modern bikes. Your bike will almost certianly have a 1.1/8" steerer tube if it has a fork made in the last 5 years or so.

    31.8mm is the diameter of handlebar that will fit, 31.8 is know as oversized, as the standard is 25.2mm but now Oversized is generally much more popular due to its lower weight (larger diameter allows for thinner walls) and increased strenght. You need to take into consideration what width your current handlebars are.

    Your handlebars mave have this information marked on them, or it may be marked on your old stem, but just measure the claming area with some measuring tape, it will be pretty obvious whether they are 31.8 or 25.2 width.

    If you could post your bike and fork, It should be obvious what your steerer tude diameter is.
  • dan1983dan1983 Posts: 314
    oh diameter! i was thinking it'd be circumference, hence my confusion with sizes!!

    cheers ollyuk, big help.

    only bought the bike last year, so assuming forks will be 1.1/8", and these are my bars: ... elID=11723

    will they be oversize? they're pretty thick.

    bike (which shows fork) is ... 5360026028

    cheers again
  • OllyUKOllyUK Posts: 230
    edited June 2008
    RaceFace do the Next XC Carbon risers in both diameters, so you could have either, go and measure with a tape measure..but make sure you measuer the claming area, not the area where you grip as the diameter is often only oversized in the clamping area.

    And if you dont mind me asking, why are you upgrading your stem?

    EDIT: And yes, you have a 1.1/8" steerer tube.
  • dan1983dan1983 Posts: 314
    Just dont like the ones thats on. Cosmetic rather than performance! I cant find any info about the one thats on, so I'm assuming its just a cheap thing.
  • OllyUKOllyUK Posts: 230
    Concept SL is just Focus' standard finishing kit, I think its own brand, but they are pretty well respected so they're not going to be poor quality. But in no way is it a "cheap thing", they're good quality Aluminium components.

    If you're purley going for cosmetics then (if you're happy with how it currently rides) keep the rise and length the same and go for the diameter that matches your handlebar (as you've ovbiously already upgraded them).
  • dan1983dan1983 Posts: 314
    These are the bars I bought

    I got them from evans anyway so I'm assuming these are them. Therefore my bars arent oversized, so cant get the stem I wanted. But going off what you're saying, I might be better off saving my money and keep the ones I've got
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