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  1. #1
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    Spacer under the stem

    Im wondering what stem length you guys using and how many spacers under you having?

    On my new bike it came with 25mm under, 5mm on top with 50mm stem. Im planing to change the stem to 40mm and not sure how low i should go for with the spacers...

  2. #2
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    There is no default answer. It is based on what works best for you, your bike geo and the feel you like.

    Lower the stem see how it feels. Raise it and see how it feels. That is how you will know.

  3. #3
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    ^^^yeah. Depends entirely on the bike, how you fit on it and how you ride. That's why it's designed to be variable. Typical range with the right size bike for a normal rider is 0-3 cm of spacers below the stem.
    Do the math.

  4. #4
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    We can answer with every combination possible.
    We can tell you "what I would run is...." with the setup you have.

    Only 1 answer will be right. The right answer is the one that you and I agree on by coincidence.


    Typically pulling the stem closer would warrant a higher bar position. But only if the position is currently ideal for you. Maybe it will feel better being closer.

    Why do you want to use a shorter stem anyway?

    Also, if you stack all spacers below the stem and the bars still feel too low, you will need to install a riser bar.

  5. #5
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    Quote Originally Posted by blkangel View Post
    There is no default answer. It is based on what works best for you, your bike geo and the feel you like.

    Lower the stem see how it feels. Raise it and see how it feels. That is how you will know.
    I understand what longer\shorter stem and more\less spacers doing, im not expecting to get an answer what will be the best for my needs, for this i will have to 'trial and error' till i find the right setting for me.

    Im just curious how others setting their stem\spacers and why...

  6. #6
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    I run a 50mm stem on my Jet 9 (w a 10mm spacer) and Fat Bike (20mm spacer) and plan on running a 70mm on my Karate Monkey (10mm spacer).

    Running those because that is what felt best. Had a 70 on the Niner felt my weight was too far forward. Shortened the stem. I also went wider bars on Niner and day bike so I shortened the stem a little. My setups are the way they are because they work best for me.

    I had a Breezer Thunder One and it had a 90mm stem because that worked best for that bike.

  7. #7
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    I try to set mine up for the type of riding I do. Between comfort and stability.

    5'8" 30in inseam

    Bike #1, 29r with a 130mm fork. Flat Bar with a 55mm Syntace Flatforce stem. One 3mm spacer under the stem. More pedaling and climbing. I feel better a bit more stretched out.

    Bike #2, 27.5 with a 150mm fork. 20mm riser and 40mm Thomson stem with no spacers. Less pedaling and more downhill.

    The more travel up front...the more I like the 27.5. Keeps the handlebar at a more reasonable height.

  8. #8
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    Im changing to shorter stem because i moved to wider bar, so it makes sense. While im changing it, i’ll experiment with less spacers to see how the riding position feels and how the bike behave. The new bike came with 25mm spacers under the stem plus 20mm rise bar and it feels a bit to high…

  9. #9
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    This calculator; Stem Comparison Tool | yojimg.net, will give you an idea if new bar positions relative to the changes you make. Don't forget to add the bar rise to see where your grips land.

  10. #10
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    Quote Originally Posted by Muddy-Runs View Post
    I understand what longer\shorter stem and more\less spacers doing, im not expecting to get an answer what will be the best for my needs, for this i will have to 'trial and error' till i find the right setting for me.

    Im just curious how others setting their stem\spacers and why...
    How and why my spacers are where they are: I set my spacer position to what is comfortable. That should answer the actual question?

  11. #11
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    On both my DJ and my stumpy evo I am running one spacer below the stem and none above. I just marked and cut the steerer because for me at least I knew that I liked my setup and there was no need to keep the extra steerer. It is a 35mm stem on my DJ and a 45mm on my stumpy

  12. #12
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    It depends on the bike and how I fit on it. On one bike I have no spacers under the stem and another I had 40mm of spacer with a zero rise bar, and now 20mm with a 20mm rise bar.

    How many spacers someone uses tells you next to nothing meaningful about their cockpit setup. Instead, look at how high their grips are compared to their saddle. Spacers are just one contributing factor to where the grips end up. The length of the fork, the head tube length, the headset spacers, stem rise, and bar rise all add up to the end height.

    In all the examples I gave above, my bars end up about level with my saddle.
    15mm is a second-best solution to a problem that was already solved.

  13. #13
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    So whats the difference between 15mm spacers under the stem with 20mm rise bar and 5mm spacers and 30mm rise bar?
    Im assuming the hight also effecting riding position as well as how the bike behave (in general and cornering) like stem length, but since its give the same rise\hight, how is it changing the bike behave?

  14. #14
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    Quote Originally Posted by Muddy-Runs View Post
    So whats the difference between 15mm spacers under the stem with 20mm rise bar and 5mm spacers and 30mm rise bar?
    Im assuming the hight also effecting riding position as well as how the bike behave (in general and cornering) like stem length, but since its give the same rise\hight, how is it changing the bike behave?
    All else being equal, they'd be the same. But typically, that's not entirely true because handlebars can be rotated to fine tune grip location and position.

    The critical part is where the grips are. How you get there doesn't matter so much, as long as you remain within design constraints of the frame, fork, and rest of the parts. Some fork manufacturers dictate a max number of spacers under the stem, especially for carbon steerers. Some don't, but you need to be aware for your setup if there are any constraints.

  15. #15
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    Asking this like like asking "What size pants do you wear and which hole do you use on your belt to hold them up?" Short of building massive matrix of data that include several rider body dimensions, the reach and stack of their bikes, the kind of terrain they ride, how flexible they are, etc., and you were able to get accurate information from thousands of riders, the answers to your question are totally meaningless. Your basic questions excludes variables such as handlebar rise, back/ up sweep, stem angle, headset stack height, headtube length, etc.

    You might as well ask, "how many roads must a man walk down before you can call him a man?"

  16. #16
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    Quote Originally Posted by Muddy-Runs View Post
    So whats the difference between 15mm spacers under the stem with 20mm rise bar and 5mm spacers and 30mm rise bar?
    Im assuming the hight also effecting riding position as well as how the bike behave (in general and cornering) like stem length, but since its give the same rise\hight, how is it changing the bike behave?
    Well, assuming they have the same length stem the 15mm worth of spacers will eat up your reach and and shorten your cockpit length but he grip will be the same height. The bars can be rotated to compensate but then you get some odd sweep and rise going on.

  17. #17
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    Quote Originally Posted by beer_coffee_water View Post
    Well, assuming they have the same length stem the 15mm worth of spacers will eat up your reach and and shorten your cockpit length but he grip will be the same height. The bars can be rotated to compensate but then you get some odd sweep and rise going on.
    Same stem length (40mm) with 0 degree, same bar with the same sweep and position (20mm & 30mm rise versions) sitting on 65.4 degree HTA (M sized Bronson v3) - the grips will be in the same hight\position.
    15mm spacers with 20mm rise bar will short the reach a bit compared to 5mm and 30mm rise bar, but except shortening the reach, how this difference\change will affect the bike behave ?

    @ mack_turtle, Tnx for sharing your knowledge, that was very helpful.

  18. #18
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    Quote Originally Posted by beer_coffee_water View Post
    Well, assuming they have the same length stem the 15mm worth of spacers will eat up your reach and and shorten your cockpit length but he grip will be the same height. The bars can be rotated to compensate but then you get some odd sweep and rise going on.
    Part of this is why I said "all else being equal (meaning ALL the handlebar dimensions except for height, including how you position the bars)" they're they same. ANY amount of raising the grips shortens the cockpit. Doesn't matter if this is done with stem spacers, or a handlebar with higher rise, or a taller rise stem.

    Quote Originally Posted by Muddy-Runs View Post
    how this difference\change will affect the bike behave
    it won't

  19. #19
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    Quote Originally Posted by Muddy-Runs View Post
    how this difference\change will affect the bike behave ?
    Spacer under the stem-screenshot_20190518-085842_samsung-internet.jpg

    The further down on the steertube you have your stem (less spacers) the more pressure your bodyweight will have on the front wheel in a seated neutral position. This is because of the increase in overall reach causing you to lean forward more. The effect, if noticed, will mostly be on flat and climbing trail sections because the height of the grips is same between combos.

    Will it make a huge difference? I am not sure. Only your body mechanics can tell you that. It may result in a more comfortable ride with less fatigue. The best way to do this is to get cheap bars and stems until you find what is right for you.

  20. #20
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    Quote Originally Posted by beer_coffee_water View Post
    Click image for larger version. 

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    The further down on the steertube you have your stem (less spacers) the more pressure your bodyweight will have on the front wheel in a seated neutral position. This is because of the increase in overall reach causing you to lean forward more. The effect, if noticed, will mostly be on flat and climbing trail sections because the height of the grips is same between combos.

    Will it make a huge difference? I am not sure. Only your body mechanics can tell you that. It may result in a more comfortable ride with less fatigue. The best way to do this is to get cheap bars and stems until you find what is right for you.
    Tnx for the info and help!

    How about having two different settings of spacers hight, stem length and rise bar hight that makes them equal in the reach\grip position, so only the contact point on the steertube will be different (lower vs. higher), how this will affect the bike behave\control in general and in cornering ?

    Im trying to get as much info as i can before im starting to buy different stems and bars to play with...

  21. #21
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    It all has more to do with fork AC and HT length that determine how many spacers there are.
    :nono:

  22. #22
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    Quote Originally Posted by LargeMan View Post
    It all has more to do with fork AC and HT length that determine how many spacers there are.
    What is AC and HT means?

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