Bicycle stem size standards - article comments

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To prevent article pages from being miles long, but preserve all the useful questions and answers provided over time, I've decided to copy/paste the website comments to the forum - and "move" further discussions here.

These are the comments from the article:
Bicycle stem size standards

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If you can't find the answer to your question in this thread, please open a separate thread with your question/problem, in an appropriate forum section (this is the Frames, forks & seat-posts section).

Relja
 
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  1. napemr
    25/03/2020 at 08:37
    Thank you, it seems like I’ve never gotten a tutorial about stem bikes as clearly as this
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    Jarno
    24/05/2020 at 22:28
    Thank you so much! This helped me a lot to buy a replacement part.
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    michael Hughes
    25/05/2020 at 14:44
    i am looking to replace a bent bracket on a Diamond back BMX mini bike. It looks like it has a threadedless stem which is 7/8 OD by 6 inches long question I have is how to ensure that the top part which is a welded bottom plate to stem with top clamp for handle bar and for bolts will be correct when ordering since sites don’t show that dimension
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    Gary
    17/08/2020 at 18:23
    I am looking for a handle bar or a substitute handlebar clamp. I have a restored single speed bike from the 1970’s. The handlebars were way uncomfortable as they wrapped around. the handlebar clamp attaches with a very long screw into the stem. The circumference of the area on the handlebar were the clamp would be is 3 inches. Diameter is just under 0.95 of an inch (24.254895017319mm). Is there a larger handlebar clamp out there? Should I just buy a new stem and if so what size stem? Can I buy a stem that will fit the bike and fit the more standard size mountain bike style handlebars?
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      Relja
      17/08/2020 at 20:45
      Give me the metric system, or give me death!
      🙂
      This article lists all the standards.
      I’m not sure what kind of stem that is, but guess it’s a quill stem.
      Measure the diameter as shown in picture 4a.
      If it’s 22.2 mm, then it’s relatively common nowadays and finding one that has handlebar clamp for 25.4 mm (1″) should be relatively easy and they are quite cheap.
      Finding one for more modern, “oversized” handlebars (1 1/4″), is not as simple, but there still are 25.4 mm bars available (at least in Serbia).
      24.25 mm is something I haven’t seen (or at least measured). Not sure where I’d look for bars that fit such stem.
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    Stuart Lewine
    09/03/2021 at 17:18
    Hi,
    I am looking to buy an adjustable stem for my Himiway E bike. The person from the company (in China -so there is probably a language issue), gave me some measurements or specs that comes stock on my present bike, but they do not make sense to me. Maybe you can help, and thank you in advance! This shouldn’t be this difficult, but I don’t want to order the wrong thing. He sent exactly this:
    Stem: MD-M400 @28.6*60E*10D*41H
    Bar: @31.8MM
    Handlebar: MTB-NR-25 @22.2*660L
    Bend: 15 degrees Bar bore: @31.8 Rise: 80 Alloy
    Stu
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      Relja
      09/03/2021 at 18:28
      Hello Stuart,
      Some guessing – since it’s not written clearly enough for me to understand (maybe someone else can, but I can’t):
      1. Fork steering column outer diameter (and stem’s inner diameter, where it clamps the steering column) is 1 1/8″ (28.6 mm).
      2. Stem’s handlebar clamp is the “oversized” – 1 1/4″ (or 31.8, or 31.7 mm – depending on how one rounds the 1 1/4″ to mm).
      3. Handlebar width – the part where grips and levers are mounted is 22.2 mm (standard MTB handlebars).
      – For details see the handlebar dimension standards.
      4. The last info is about the stem’s angle (15 degrees), handlebar gripping diameter (repeated here?), and it would make sense to provide length in mm, but it says “Rise:” – no idea why.
      I suppose that “Alloy” refers to “aluminium alloy.”
      If all that is correct (i.e. if I didn’t misunderstand the given info), I would expect these to fit (Amazon affiliate links – showing what the matching stems look like):
      adjustable stem 1
      Similar, different make, a bit shorter

      Relja
 
  1. Bradley Casson
    04/04/2021 at 10:19
    Do most bikes have a 1 1/8 or is anything smaller? I’m wanting to upgrade my forks bjt make sure it fits
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    Robert Clark
    26/04/2021 at 13:55
    I got a Wake 780mm aluminum bar to mount on FOMTOR stem and it was a perfect fit. This is easy to install and haven’t had an issue for the first couple rides. The 60mm rise is half of what the stock stem length was, so my hand position is closer to my body, which is much more ergonomically comfortable. I definitely recommend this stem.
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    Ed Aukema
    02/05/2021 at 18:54
    Can a threadless stem be mounted on the inside of the steering column istead of outside(furthest from the rider) my wife loves her bike but as she gets older she dislikes bending over as much as she needs to. Was looking into purchasing a cruiser style handle for her. Looking at the bike it suddenly hit me about the possibility of switching it up instead.
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      Relja
      02/05/2021 at 19:21
      Hi Ed,
      I’d prefer the bars to be in front of the steering column. At least a bit.
      There is the option of using an adjustable stem (Amazon affiliate link for the decent-quality Ritchey model).
      It can be set to point 55 degrees upward, making the bars be higher, and closer to the rider.
      Relja
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      Jon Thompson
      26/04/2023 at 16:52
      This is a bad idea. The nature of steering a bicycle is that you turn the handlebars in the direction you want the wheel to go. If the stem and handlebars are backwards, you now turn them opposite the direction you want the wheel to go.
      While the human brain can handle this, physics cannot. Putting the handlebars over the wheel means that whatever body weight is supported by your hands is supported by the wheel. If the handlebars are opposite the wheel your body is no longer supported by the wheel and you’re asking for a crash unless you’re moving _very_ slowly.
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    Andrew Black
    12/08/2021 at 22:19
    A small correction. Above you have written: “Standard for most threaded forks with an outer diameter of 31.8 mm (1 ⅛″)”. Well, as you have written elsewhere, 1 ⅛” is 28.575mm, not 31.8mm
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      Relja
      13/08/2021 at 06:39
      Hi Andrew,
      Thank you very much for the correction – much appreciated.
      I’ve fixed the error.
      Relja
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    Paul Steenwyk
    29/04/2022 at 05:14
    This was very helpful. I appreciated the clear description of terminology, as well as the helpful pictures of exactly where to measure to size for the right bike stem.
 
  1. Christopher Lyons
    28/08/2022 at 04:11
    I have a bicycle from I believe 1976 and it does not have a 22.2 MM stem but smaller.
    I am uncertain what size I think possibly 16 or 18 mm.
    Sincerely, Christopher I have
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    Jack Ducan
    09/01/2023 at 03:55
    A threaded headset is also beneficial for road bike riders who wish to achieve comfort while sporting an upright cycling position when cycling, but the replacement of parts, such as forks and stem tubes, is expensive due to their limited market availability.
 
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