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  1. #1
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    How Much is Too Much - Stem Spacers

    Hey;

    I've always wondered, and I guess like everything it would depend...

    I've always had no choice but to stack up the spacers on my stems, but I've never liked it. I've got 50mm of spacers with 7" HT right now, and was considering using an 8 next time just to cut down on the stack. Then there is something like pictured below. I fully understand that when you are tall, you "don't have any choice", but I just can't imagine that being the best idea, long term at the least.

    Thoughts?
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  2. #2
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    My thought on this is simple and I know I've said it before. The head tube is exactly the number of spacers you use too short if you have spacers. That's just how I see it though, I just use the scuff washer that CK provides between the headset and the stem on all my bikes.

  3. #3
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    Best is about 10mm of spacer above or below the stem.
    In your case, start with a 30 or 40 degree rise stem. It's always best to use stem instead of spacers.
    It looks like you need a custom bike.

  4. #4
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    Trailmaker, I saw that setup on the fat forum and thought the same thing. i know you build your own frames so if you know you need the height I say go for the longer head tube. I do like a small amount of spacers just for adjustment purposes but once you find your spot I'm guessing you don't move it much.

  5. #5
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    Just preference/aesthetics

    As long as the head tube is long enough to handle the forces on the frame, it's just a matter of preference. My cargo bike has probably a foot of spacers - because I want to be able to get the bars an appropriate height for any rider, if someone small needs to ride it (obviously I'd use a shorter stem as well in that instance).

    Personally I like to have the rider use a few spacers, because you never know when someone is going to want to move the bars up/down a little (maybe you started doing yoga and you've got a bit more flexibility, or whatever). You can do quite a bit with bar and stem too, of course. I like to make sure my customers have a couple of inches of adjustability (including swapping bars and stems) up or down from their current desired position.

    So use as many or as few as you think looks good, as long as you've got at least at 100mm or so head tube.

    -Walt
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  6. #6
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    Some forks have specs on the number of spacers that can be used -- unsupported length above the HS. I've recalled seeing 2" on some on the past (don't remember what). I'm surprised it's not more prevalent to have the spec out there.

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    If you need your hands up that high you may want to get the rise via BMX style bars. The advantage of stem/bars to get the rise is that it helps you keep the top tube low for increased stand over height.
    Mark Farnsworth, Raleigh, NC
    http://farnsworthbikes.com

  8. #8
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    Hmmm...

    No one really sees it as a structural issue. They seem to flex a lot more. Maybe I equate flex with structural inadequacy, and that might not be proper. I know it has always bugged me, at least philosophically, but there has been little to be done about it. I simply thought that the bike setup shown in my first post was excessive. It certainly does not represent what I consider a long enough HT for a 20" (assumed) frame.

    My current stable pictured below, covering 8 years of riding; XL Heckler, XL RIP9, XL+ TrailMaker Humvee. Stacked on up! Guess I wont worry about, or I'll start looking harder for 35* rise stems.
    Attached Thumbnails Attached Thumbnails How Much is Too Much - Stem Spacers-mystemspacers.jpg  

    Last edited by TrailMaker; 01-23-2013 at 09:16 AM.
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  9. #9
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    it's a structural issue with carbon. Even the thinnest steel steerer can be used full length if you want.

  10. #10
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    Quote Originally Posted by Feldybikes View Post
    Some forks have specs on the number of spacers that can be used -- unsupported length above the HS. I've recalled seeing 2" on some on the past (don't remember what). I'm surprised it's not more prevalent to have the spec out there.
    The converse of that is that some forks require a minimum length of spacers as well--I don't know which ones, but I do know there are some carbon steerer forks that need to have at least a little spacer between the stem and the headset to keep the steerer from shearing off. It seems like there was a discussion around this during the TdF one year after a guy had the fork fail. I'd have a link, but I don't use carbon steerers on anything so it's not relevant to me.

  11. #11
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    Quote Originally Posted by unterhausen View Post
    it's a structural issue with carbon. Even the thinnest steel steerer can be used full length if you want.
    Will the manufactures of those forks back that up?

    Most production fork makers say that 4cm is the limit on spacers. There have been a few forks that were designed for more. I remember a no out of production Alpha Q fork that Zinn got them to make that was rated to run unlimited stack. Enve might do something similar these days. The reality is that you should check with the manufacture to see what the stack threshold is.

  12. #12
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    Quote Originally Posted by customfab View Post
    The reality is that you should check with the manufacture to see what the stack threshold is.
    I agree, that's why I said it was an issue with carbon steerers, particularly when considering the potential issues of crushing them with the stem.

    I'm sure you could make a carbon steerer that would work with a meter of spacers. However, the people that want carbon forks would rather go with lighter weight steerers that require some care.

  13. #13
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    Quote Originally Posted by jay_ntwr View Post
    My thought on this is simple and I know I've said it before. The head tube is exactly the number of spacers you use too short if you have spacers. That's just how I see it though, I just use the scuff washer that CK provides between the headset and the stem on all my bikes.
    +1

    I will say that having some fudge room for fine tuning / different stem stack height is nice. Especially as nice stems are getting harder to find with more than -+6deg.

    I will also say I recall seeing somewhere that a carpet fiber steerer manufacturer wanted at least a 5mm spacer above the stem...

    IMO standover clearance is waaaaaaay over-prioritized these days. The HT is the length it needs to be......Somewhere along the line someone who got racked riding the biggest Schwinn Traveler produced when they were eight years old convinced the world that standover clearance is paramount to bicycle fit. I toss published standover heights in with laterally stiff/vertically compliant/nimble/stable/eleventeen%stiffer marketing.
    Slowly slipping to retrogrouchyness

  14. #14
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    Quote Originally Posted by unterhausen View Post
    I'm sure you could make a carbon steerer that would work with a meter of spacers. However, the people that want carbon forks would rather go with lighter weight steerers that require some care.
    I would say that holds true if we are talking suspension forks. But pretty much every quality road fork these days is all carbon.

  15. #15
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    At Interbike 2007 I brought this topic up and wrote about it here.

  16. #16
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    Quote Originally Posted by Howley View Post
    At Interbike 2007 I brought this topic up and wrote about it here.
    Interesting;

    This caused me to think yet again about the topic, and I came to a new point, yet again. That much stack height obviously allows a lot of flex in the steerer. Yes, the spacers can squirm around, and I've even found the carbon ones getting somewhat significantly abraded! The interlocking spacers is an interesting idea, and I'm a bit surprised they are not more common, really. I had been thinking that the ultimate solution was to get some stock and make a solid 1-piece alloy spacer. Your offering triggered another perspective.

    Where there is flex, it is very often important to spread forces over as large an area of a given piece as possible. In the case of any given steerer tube, this is the state that likely exists with a big stack of spacers. The entire length of the steerer is allowed to flex just a tad if the stack is slipping a bit on each interface. Locking those spacers together, or making them one solid piece, would focus ALL of that force in two places; the base of the stem clamp and quite a bit at the top bearing. Theory, indeed.

    The more I think about it, the more I am drawn back to the much castigated and maligned riser stem as the best solution. Not many 31.8 risers out there.....
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  17. #17
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    IMO,
    A riser stem offers the best interface to the steerer tube, if you just need a bit of rise.
    And,
    If you want to maintain that low stand-over heigh, high handlebar situation, and need more than what is currently offered, the other choice is a high-rise handlebar.

    The BMX guys/Gals torque the heck out of their stuff, and they don't seem to have a problem with a high-rise handlebar.

    Also,
    IMHO,
    Stacking spacers, or using an extra thick spacer, is just asking for trouble.

    It's no different than stacking a bunch of washers onto a bolted assembly, because you can't/won't locate a proper length fastener.
    Last edited by bikeabuser; 01-23-2013 at 08:10 AM.

  18. #18
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    Amazon.com: Dimension 31.8 110mm 125 Degree Black Stem: Sports & Outdoors

    Dimension makes some weird stuff. I had an old Dimension stem that was 125mm 35 degree rise. Looked ridiculous and the bolts were huge!

    I believe there is no substitute for a taller head tube. The spacers and stem can get your hands where they need to be but they can't reduce the amount of stress and torque on the steerer or headset bearings.
    When the chicks at school see how gay we are, they're gonna be all over us.

  19. #19
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    Indeed;

    There are some of the companies out on the fringes that make some funky stuff, Dimension being one of them.

    Do realize that the third of the front ends that I pictured above is already with a 7" HT!!!

    Contemplating the BMX route takes me back to the dreaded days when I stripped out stems regularly because they just wouldn't hold. Those that did hold (or that I welded!) often snapped! In the pre-BMX craze dayz, it was a real treat to score a Schwinn cast stem!
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
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  20. #20
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    Quote Originally Posted by TrailMaker View Post
    Indeed;

    There are some of the companies out on the fringes that make some funky stuff, Dimension being one of them.

    Do realize that the third of the front ends that I pictured above is already with a 7" HT!!!

    Contemplating the BMX route takes me back to the dreaded days when I stripped out stems regularly because they just wouldn't hold. Those that did hold (or that I welded!) often snapped! In the pre-BMX craze dayz, it was a real treat to score a Schwinn cast stem!
    I only see the one pic in your original post. The other post with attached images is empty...
    When the chicks at school see how gay we are, they're gonna be all over us.

  21. #21
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    Damnn things...

    I use different browsers and see one pic or the other!

    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
    - John Hajny, a.k.a. TrailMaker

  22. #22
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    Surly says this...

    "How many stack spacers can I use on my Surly fork?Hey, go nuts. Seriously, these are beefy steel steer tubes and there is no lawyer breathing down our collective necks saying you can only have a couple of spacers. Geek out, stack 'er all the way up if you like."

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