# how many headset spacers is too many?



## futurerocker1 (Sep 16, 2009)

right now I currently have 4 10 mm spacers, 3 below stem and one above. I was thinking about trying 2 on top.. but this would have looked goofy. How many spacers do you run? how many is safe/recommended?


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## Hopping_Rocks (Aug 23, 2008)

You can have zero, or as many as you need to fill up the space on the steer tube.


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## intoflatlines (Mar 31, 2010)

With my old stem I had 1 x 10mm, 2 x 3mm, and 1 x 2mm.

I just put on a new stem that is shorter and now I have 2 x 10mm, 2 x 3mm, and 1 x 2mm.

It brings the stem to where I need it and doesn't look bad at all. I remember some guy made a couple threads on here a month or so back and he had like 15+ cm of spacers on.. now that looked goofy.

Edit: I see that you were talking about spacers on top.. I thought you were talking about spacers on the bottom. I think a couple of cm on top wouldn't be bad but any more and it might become more dangerous/painful.


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## highdelll (Oct 3, 2008)

I don't think spacers on top look goofy


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## JonathanGennick (Sep 15, 2006)

futurerocker1 said:


> right now I currently have 4 10 mm spacers, 3 below stem and one above. I was thinking about trying 2 on top.. but this would have looked goofy. How many spacers do you run? how many is safe/recommended?


What you have is 40cm of room to play with in order to move the bars up and down to a position that you like. You can buy different size spacers and change up the order until you're happy w/the result.

If you like a result with spacers on top, but don't want the spacers on top, you can have your local bike shop cut down your steerer tube to shorten it. Think twice before doing this. It is not possible to uncut.

Last year I ran a bike all season with a five or six cm of spacers on top of the stem, because I wanted to leave headroom to change over to drop bars. (I did change this year. I wish I had left just one more spacer last year).

My personal preference is to measure things out such that I need at least a (usually) 5mm spacer on top of the stem. That way, I know that 100% of my stem is in contact with the steerer.


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## Dremer03 (Jun 19, 2009)

I have 5cm of spacers, and my stem is all the way at the top of my uncut steerer tube. I used to run it much lower with spacers on top, but switched them around to be in a more comfy position. Soon enough I will have a riser bar, and I might finally cut the steerer tube when I get my position sorted out.


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## Squash (Jul 20, 2003)

*In answer to your....*

original question, ther is no mimimum or maximum rule when it comes to steerer tube spacers. 40mm isn't that much, it's only 4cm or 1.57 inches. On my commuter I've got it set up with 50mm of spacers to give a good upright riding position. It reduces stress on the back and neck muscles and offers better visibility. I don't have to lift my head near as much to see down the road.

The only draw back is if you use a bunch of small spacers to make up that distance they can shift a bit, cause noises, creaks etc., and are not as efficient in transfering the torque from the top cap to the headset in preloading the head set bearings. Even high quality spacers aren't perfect and can shift a bit and unevenly load the bearings. So it is wise to use the largest spacers you can get to fill that gap, and save the smaller ones for fine tuning. In your case 4 10mm spacers is just fine.

As for moving a couple up top. Some folks think it looks goofy, but it is a valid method for testing different bar heights to see what suits you best without making a permanent cut. Lets face it, you can always cut some off, but you can't put it back on if you make a mistake! So juggling spacers up and down is a VERY good idea until you settle on a bar height that you like. If you intend to get a riser bar down the road then DON'T cut that steerer until you have it on the bike. I never cut a steerer tube until I have settled on the bar and stem that I intend to use, and then the bar height dialed in. And even then I'm usually inclined to leave 10 or 20mm above the stem for any future changes I might make.

So go ahead and move those spacers around. It's a good tool to dial in bike fit and riding position. Once you've got it tweaked to your liking then cut the steerer if you want. Just don't do it before you've got it all figured out. :thumbsup:

Good Dirt


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## futurerocker1 (Sep 16, 2009)

thanks for all the replies guys.. this was my first build and I was cautious to cut the steerer tube, that's why I left it so long. I also want to be able to use the fork on other frames if I ever decide to switch. Here's a pic where you can kind of see the setup I have, unfortunately my bikes at home and im at school for finals so i wont be making any changes yet.


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## smilinsteve (Jul 21, 2009)

Leaving room on your steer tube is just logical
- to adjust stem height, 
-to accomodate stems with taller clamps, or
- to allow transfering the fork to a new frame with longer head tube.

A lot of bikes don't have spacers above the stem, purely because someone decided it is not pretty. I think that's dumb. 

In the old days before aheadset style headsets, stems were quill type, and it was easy to adjust stem height. Now you need some extra steer tube.


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## AndrwSwitch (Nov 8, 2007)

There's one thing to be cautious with with a big spacer stack. It does put more leverage on an unsupported part of the steer tube, and some lightweight steer tubes aren't designed to take that. Check your fork's manual - if it applies to it, there should be a note in the installation section that tells you how many spacers is acceptable.

Other than that... whatever makes the bike fit you is the right configuration.


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## smilinsteve (Jul 21, 2009)

AndrwSwitch said:


> There's one thing to be cautious with with a big spacer stack. It does put more leverage on an unsupported part of the steer tube, and some lightweight steer tubes aren't designed to take that. Check your fork's manual - if it applies to it, there should be a note in the installation section that tells you how many spacers is acceptable.
> 
> Other than that... whatever makes the bike fit you is the right configuration.


Good point (referring to spacers under the stem, not above).


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## smilinsteve (Jul 21, 2009)

This was posted on another thread:

http://forums.mtbr.com/showthread.php?t=585593


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## squibbtp (Jul 3, 2009)

smilinsteve said:


> This was posted on another thread:
> 
> http://forums.mtbr.com/showthread.php?t=585593


wow that is super high!


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## manual63 (Nov 5, 2006)

If you have too many above, it doesn't matter what it looks like or not. It's not all that safe in my opinion. The steerer tube sticking up with spacers on it is just looking to impale your body somewhere......and it would not be fun. I would only do it to test out and get the bar and stem height dialed, then cut that sucker so you don't have something waiting to impale you when you crash.

As far as having them stacked a bunch below. If you are doing this, something isn't right. Frame is too small, bars are too low, and so on. If you need to run a bunch of spacers below, run a higher rise bar and reduce those spacers. Frames and headtubes are not designed to take the extra leverage of a stem way up in the air like that. All it does is weaken the steerer tube because it now has less support and stresses the headtube of the frame more.

You can do what you want, but I don't recommend and extreme above or below the stem. It's just unsafe.


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## mtbnozpikr (Sep 1, 2008)

smilinsteve said:


> This was posted on another thread:
> 
> http://forums.mtbr.com/showthread.php?t=585593


I've seen that before...


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## FroggyBiker (Jan 26, 2009)

YA Ummmmmm I dont thats what he ment when he asked about headset spacers.......though I guess you could call em that!


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## jeffj (Jan 13, 2004)

It (more spacers under the stem) does provide a more upright riding position which some will prefer. Just know that it does alter handling when headed downhill. On steep descents, it's kind of nice to get the bar up a little. But on less than steep descents, it isn't as easy to get the front wheel weighted well enough to keep from pushing (understeer) in corners, and if you can get your weight positioned above the bars, your elbows will be bent a LOT. In other words, it can have some negative handling implications too.

Spacers above the stem are good for having the ability to to go higher with the stem if needed, but they can be more likely to snare ones scrotum (if one does indeed have a scrotum). 

While the probability of this happening is not high, it can happen. It happened to a friend of mine, and it was not pretty. He doesn't have the 'snare' there any longer, and in fact, now has a BMX style stem pad in place to guard against further stem-to-crotch violence. He also has a custom sticker on his top tube in a nice calligraphy style font proclaiming him to be "Sir Nardington of Testiclania". Friends can be brutal.


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## mtbnozpikr (Sep 1, 2008)

jeffj said:


> While the probability of this happening is not high, it can happen. It happened to a friend of mine, and it was not pretty. He doesn't have the 'snare' there any longer, and in fact, now has a BMX style stem pad in place to guard against further stem-to-crotch violence. He also has a custom sticker on his top tube in a nice calligraphy style font proclaiming him to be "Sir Nardington of Testiclania". Friends can be brutal.


That makes me cringe just reading it. His new title is the funniest thing I have seen all day. Thanks for the laugh.


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## raleigh5 (May 30, 2011)

how about doing away with spacers altogether? and the star nut too.

Hands Up! Adjusting Handlebar Stem Height on Your Bicycle


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## got6ponies (Sep 16, 2011)

i keep my spacers on the bottom. less stuff my knees wont hit.


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## TwoTone (Jul 5, 2011)

Hopping_Rocks said:


> You can have zero, or as many as you need to fill up the space on the steer tube.


Not true, forks have a maximum height that the stem should be above the headset.


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## kapusta (Jan 17, 2004)

manual63 said:


> As far as having them stacked a bunch below. If you are doing this, something isn't right. Frame is too small, bars are too low, and so on. If you need to run a bunch of spacers below, run a higher rise bar and reduce those spacers. Frames and headtubes are not designed to take the extra leverage of a stem way up in the air like that. All it does is weaken the steerer tube because it now has less support and stresses the headtube of the frame more.
> .


Whether you use 50cm of spacers and a flat bar or 10mm spacers and a 40mm riser bar, does not matter in terms of the stress on the head tube. Assuming the grips end up in the same position, the stress on the head tube is the same.

It does put _different _stresses on the steer tube, though, because it is putting it on a different part of it. I'm not convinced it is necessarily MORE stress, though. Again, assuming the grips are in the same position.


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## TwoTone (Jul 5, 2011)

kapusta said:


> Whether you use 50cm of spacers and a flat bar or 10mm spacers and a 40mm riser bar, does not matter in terms of the stress on the head tube. Assuming the grips end up in the same position, the stress on the head tube is the same.
> 
> It does put _different _stresses on the steer tube, though, because it is putting it on a different part of it. I'm not convinced it is necessarily MORE stress, though. Again, assuming the grips are in the same position.


Simple physics, you're creating a long lever so yes more stress.


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## mtbnozpikr (Sep 1, 2008)

TwoTone said:


> Simple physics, you're creating a long lever so yes more stress.


I couldn't agree more.


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## AndrwSwitch (Nov 8, 2007)

I always get nervous when someone uses the phrase "simple physics."

If someone uses a few fewer spacers but makes up for them with a higher-angled stem or using riser bars, the stem or handlebar just exerts more torque on the next component in line. At the top of the headset, it's a wash.


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## kapusta (Jan 17, 2004)

TwoTone said:


> Simple physics, you're creating a long lever so yes more stress.


Yes, and the same applies to the riser bar vs the flat bar.

The "lever" that puts stress on the head tube is between your grips and the top of the head tube. In both scenarios (where the grips end up in the same position relative to the head tube), the lever is the same length. The "lever" consists of the steerer sticking up AND the bars (and the stem as well).

Here is an analogy: You are pushing down on a 4' long lever that has 2 grips on it. One lever makes a simple "T" at the top and the grips to the lever are at the ends, 2 feet apart. Switch that out for another lever that is the same at the bottom, but about 2 feet up it splits into a "V" for the remaining 2 feet of length, and the grips are at the end of that, 2 feet apart.

Assuming that the grips on each lever end up in the same position and orientation relative to the other end of the lever, you are going to have the exact same mechanical advantage with either one. This is because the shape of the bar itself is not really relevant, unless it leads to some difference in stiffness.

It is the same thing with bars, stems, and steer tubes, when looking at the forces on the head tube created when you apply force to the grips on the handlebar.


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## womble (Sep 8, 2006)

TwoTone said:


> Simple physics, you're creating a long lever so yes more stress.


I think the only relevant 'simple' consideration here is that the stress on the headtube from below (long lever and large amounts of force from the wheel slamming into obstacles) is going to vastly outweigh any force from above the headtube (comparatively puny forces exerted by the rider's body on the steerer).

The 5-10cm extra lever on top is simply not relevant compared to the 100cm of lever length below.

(Kapusta and Andrw are taking things in a slightly more complex direction, but I think they're fundamentally correct as well.)


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## kapusta (Jan 17, 2004)

AndrwSwitch said:


> I always get nervous when someone uses the phrase "simple physics."
> 
> If someone uses a few fewer spacers but makes up for them with a higher-angled stem or using riser bars, the stem or handlebar just exerts more torque on the next component in line. At the top of the headset, it's a wash.


Yes it is both simple and complex

On the one hand it just a lever that goes from the grips to the top of the head tube. IF the lever is the same, the forces on the head tube are the same.

On the other hand trying to prove this by calculating all the the different forces that go from bar to stem, stem to steer tube, steer tube to head tube in order to show that all the different bar/stem/spacer combinations come out the same is pretty complicated. Not sure I would even know how to do it.


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## Timon (May 11, 2008)

i was reading a rockshox reba sl manual yesterday and there was a diagram showing a MAX spacer allotment of 30mm below the stem.

not sure if that applies to other forks.


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## jgerhardt (Aug 31, 2009)

nomit said:


> i was reading a rockshox reba sl manual yesterday and there was a diagram showing a MAX spacer allotment of 30mm below the stem.
> 
> not sure if that applies to other forks.


Reading the manual to see what the manufacturer recommends, now THAT is a novel solution!


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## smilinsteve (Jul 21, 2009)

kapusta said:


> Whether you use 50cm of spacers and a flat bar or 10mm spacers and a 40mm riser bar, does not matter in terms of the stress on the head tube. Assuming the grips end up in the same position, the stress on the head tube is the same.
> 
> *It does put different stresses on the steer tube*, though, because it is putting it on a different part of it. I'm not convinced it is necessarily MORE stress, though. Again, assuming the grips are in the same position.


Ok I think I'm with you. Looking at the bearing load on the top headset bearings, it is going to be the same for a given hand position, whether you use spacers, riser bar, angled stem etc. to achieve that hand position. 
But, bending stress on the steer tube does change depending on the height of the stem attachment on the steer tube. 
So, limits for spacer height are designed to limit steer tube stress, not head tube stress or bearing load.

For example, I can isolate the steer tube and upper headset bearing and put 100lb of compressive force radially on the bearing with no bending moment on the steer tube. Or, I can move my force upward on the steer tube, keep the radial force on the bearing at 100lb, but now there is a bending stress on the steer tube equal to the force times the moment arm.

Does that sound right to you geniuses?


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## TwoTone (Jul 5, 2011)

smilinsteve said:


> Ok I think I'm with you. Looking at the bearing load on the top headset bearings, it is going to be the same for a given hand position, whether you use spacers, riser bar, angled stem etc. to achieve that hand position.
> But, bending stress on the steer tube does change depending on the height of the stem attachment on the steer tube.
> So, limits for spacer height are designed to limit steer tube stress, not head tube stress or bearing load.
> 
> ...


Thank you, that was my point, its simple, you raise the point of attachment on the steering tube you create a longer lever.

It doesn't matter where the bars and grips are, the stem is still clamped higher on the steer tube increasing the chances of bending it.


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## AndrwSwitch (Nov 8, 2007)

Sort of...

If you model the situation as planar, which is accurate enough IMO and a whole lot easier, there are three components of force that are interesting. One is axial force - along the steer tube. The next is applied shear force that's perpendicular to the steer tube. And the last is moment.

The axial force can be more-or-less ignored - it just travels straight through the steer tube to the fork, the wheel, and the ground. Absent a beer can issue, it doesn't effect the system.

The shear force is the one that everybody's worried about. And it's true that the bending moment it generates at any given point, say the one right around the top bearing, is more if the spacer stack is taller.

But you also have to consider the applied moment. Change the size or shape of the stem, and this changes too. In the example of using a slightly longer and higher-angled stem or a set of riser bars and a shorter spacer stack to achieve the same thing as a shorter, lower-angled stem or a set of flat bars and a taller spacer stack, the riser bars or higher-angled stem constitute a longer lever, so they'll apply more moment to the steer tube. The sum of the applied moment and the bending moment from the shear force are going to be the same, below the stem, as they would be at the same point relative to the top bearing for the other handlebar/stem/spacer configuration, as long as the place where the force is applied - the location of the grips - stays constant.

The truth is I don't have a great idea of where the 30mm limit comes from. I was wondering last night if maybe it's actually to do with the amount of deformation of the steer tube that's permissible. Or, maybe it's just a way for the engineers who design suspension forks to limit how far away it's possible to put the grips. Maybe they're trying to expose less steer tube to other kinds of applied forces, like someone whacking it into something when he crashes.


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## kapusta (Jan 17, 2004)

smilinsteve said:


> For example, I can isolate the steer tube and upper headset bearing and put 100lb of compressive force radially on the bearing with no bending moment on the steer tube. Or, I can move my force upward on the steer tube, keep the radial force on the bearing at 100lb, but now there is a bending stress on the steer tube equal to the force times the moment arm.
> 
> Does that sound right to you geniuses?


I'm not one of the geniuses, but.....

I believe you are addressing the differences among different bar/stem/spacer combinations (which yield the same grip to head tube position) in the stresses on the steer tube? If so, this is my non-mathematical way of looking at it:

I think within the specific example you give, you are completely correct. However, I think the example leaves out a critical difference between the two scenarios: The affect of using high rise bar/stem combo vs a flat(er) combo on the steer tube where it clamps.

I've try another analogy: Take a flat bar and grab it where the stem clamps. Now try to hold it while I hold the grips and push and pull back and forth (we'll assume that you have gloves that can get a good grip). Now try the same thing with a bmx bar with 5" of rise. This one is going to twist in you hands as you try to grip it.

If you have a riser bar, there is more bending/twisting on the steer tube where the stem is clamped. If you move the force up but use a flat bar, there is not as much twisting at the stem., but the mechanical advantage is greater.

Applying this same concept to the example you gave, when you are applying the force at the bottom of the steer tube(assuming you are trying to recreate the forces from a higher rise bar/stem combo) you also need to add some "twisiting" forces (for lack of a better vocabulary on my part) to the steer tube that will be less than what you would apply farther up.

This is what I meant when I said the forces are "_different _" on the head tube. What I do not know is which ultimately is more likely to cause the steer tube to fail.

One other point. To stick with your specific example, if you are keeping the forces at the head tube the same, you would be exerting LESS force against the steer tube as you move up it.


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## mtbnozpikr (Sep 1, 2008)

AndrwSwitch said:


> Sort of...
> 
> If you model the situation as planar, which is accurate enough IMO and a whole lot easier, there are three components of force that are interesting. One is axial force - along the steer tube. The next is applied shear force that's perpendicular to the steer tube. And the last is moment.
> 
> ...


That's a good description of what's actually happening. As for the 30mm limit you mentioned, I too wonder where the number comes from.


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## kapusta (Jan 17, 2004)

TwoTone said:


> Thank you, that was my point, its simple, you raise the point of attachment on the steering tube you create a longer lever.


If you are talking about using the _same _bar and stem combo, and simply putting more spacers under one of them, then yes, there is more stress on both the head tube and steerer on the one with more spacers. But that is not what we are talking about here.

Even in his example (which is accurate, though as I pointed out in a response, not quite complete), you will note that he specifies the same forces _at the head tube_. If that is the case, then you are applying less force to the steer tube as you move higher.



> It doesn't matter where the bars and grips are, the stem is still clamped higher on the steer tube increasing the chances of bending it.


Just to be clear, I don't think that is what he said (that is does not matter where the grips and bar are).

I think you may be confusing the stresses on the head tube with the stresses on the steer tube. The steer tube is just PART OF the lever with respect to the head tube.

As far as bending the steer tube:Simply making a lever longer does not make the lever itself more likely to bend IF you are decreasing the forces on it (which you are doing when you use a low rise bar/stem as opposed to a high rise bar/stem).


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## kapusta (Jan 17, 2004)

mtbnozpikr said:


> That's a good description of what's actually happening. As for the 30mm limit you mentioned, I too wonder where the number comes from.


I am guessing that they need to keep the recommendations simple, and when they say "30mm", they are accounting for the highest rise bar/stem combo that someone is likely to run with it.

Again, that is just my guess.


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## smilinsteve (Jul 21, 2009)

kapusta said:


> I am guessing that they need to keep the recommendations simple, and when they say "30mm", they are accounting for the highest rise bar/stem combo that someone is likely to run with it.
> 
> Again, that is just my guess.


It looks to me like the 30mm is Rockshox max for carbon steerers, and they don't give a max for aluminum, here:

http://www.sram.com/_media/techdocs/95-4015-023-000 Suspension Fork - Rev C.pdf


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## kapusta (Jan 17, 2004)

Stripes said:


> I have 40mm of spacers below my stem (back issues) and 5mm above. It's on a Fox 36 so I'm not expecting it to cause any trouble with stress and force from regular riding with a 180 lb rider unless I plan on going 6 feet to flat (which seems like a bad idea anyway).
> 
> Some people like myself have back issues and this may be the only comfortable way to ride. While I'm working on strengthening my core, being too bent over can cause me days of pain that I'm willing to sacrifice the traditional stem to head tube look for


I'm in the same boat. Luckily for me, most mtb frames work out OK, but for road bikes it has been a real issue. Below is my Casseroll with it's enormous spacer stack.


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## xxxxx (Aug 29, 2011)

I just lowered my bar by moving about 7 or 8 mm or spacers above the stem I had flipped my stem awhile ago too. During XC riding what are the disadvantages of a lower bar assuming the riding position is comfortable?


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## AndrwSwitch (Nov 8, 2007)

xxxxx said:


> During XC riding what are the disadvantages of a lower bar assuming the riding position is comfortable?


Maybe none. Maybe you'll find that it's harder for you to loft your front wheel, and your bike sometimes nosedives in compressions.


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## xxxxx (Aug 29, 2011)

AndrwSwitch said:


> Maybe none. Maybe you'll find that it's harder for you to loft your front wheel, and your bike sometimes nosedives in compressions.


Okay. Thanks I will look for that behavior. I thought maybe it would be harder to pull the front up but I hadn't thought about the front end diving as my weight is more forward. I'm going to check those issues. Thanks again.


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## smilinsteve (Jul 21, 2009)

On the plus side, more weight on the front could help with cornering, but the change you made is a pretty minor adjustnent.


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## neavissa (Sep 26, 2009)

mtbnozpikr said:


> i couldn't agree more.


+1.


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## Grassblade23 (Sep 16, 2015)

*SNoT*



jeffj said:


> ...It happened to a friend of mine, and it was not pretty. He doesn't have the 'snare' there any longer, and in fact, now has a BMX style stem pad in place to guard against further stem-to-crotch violence. He also has a custom sticker on his top tube in a nice calligraphy style font proclaiming him to be "Sir Nardington of Testiclania". Friends can be brutal...


I hate to be the guy to resurrect an ancient thread, but I had to comment on this.

I am currently assembling my first Full Suspension bike. It is a donated frame, and it has the remnants of "Sir Nardington" on the top tube, and "SCV Dirtbags" elsewhere on the frame.

Small world.

<edit>To make this even more random, I found this thread by looking up a question relating to BMX.


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## noose (Feb 11, 2004)

That looks great!


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## jacksonlui (Aug 15, 2015)

There doesn't seem to be a consensus here. It makes sense that if the stem is way above the headtube, there would be more angular force which will add extra stress. It probably wouldn't matter unless you bottom out your fork all the time.


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## One Pivot (Nov 20, 2009)

If you have a silly huge spacer stack, you've got maybe 60mm of lever. The other end of your fork has ~500mm.

If the fork will hold the stress from the long end, it'll hold the much much shorter end as well. Even taking into account stem length, its incomparable.


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## jeffj (Jan 13, 2004)

Grassblade23 said:


> I hate to be the guy to resurrect an ancient thread, but I had to comment on this.
> 
> I am currently assembling my first Full Suspension bike. It is a donated frame, and it has the remnants of "Sir Nardington" on the top tube, and "SCV Dirtbags" elsewhere on the frame.
> 
> ...


Holy Chit! Small world indeed. Funny that you found this by searching for something else.

Chumba XCL, right? That is one stout frame. For all of the 'history' it has written, it was still looking great when I stripped the parts to migrate them to a Giant Reign build a few years back. I think I still have the wheelset from it hanging in my mancave. Glad to know it will still see some action.

I titled that ride report "When Johnson Met Thomson". I saw the incident happen. If it was a You Tube video, it would have gone viral. His screams of pain are likely still bouncing off of the San Gabriel mountains. I don't want to get too graphic, but his man-berries suffered almost to the point of . . . . ruination.

The SCV Dirtbags was a group I started on the socaltrailriders website back when it was pretty popular. Most of the group has migrated to imtbtrails now. My handle there is 'Daddy Dirtbag'.


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## jacksonlui (Aug 15, 2015)

I asked a builder and he said Fox recommends a max of 40mm spacers. I put 45mm in mine only because I didn't have spacers that added up to 40mm. I like a longer stem to allow for flexibility in riding position as well as resale value.


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## Ben Bravis (Jul 6, 2015)

Speaking from experience here, spacers on top is a BAD idea. I once had 2cm of spacers on top, never again! Go OTB just once with those spacers and you'll get it...

Sent from my XT1080 using Tapatalk


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## TheUnknownRider (Oct 2, 2015)

dare I make my first post on this forum by suggesting that the people commenting negatively about too many stem spacers likely don't give a second thought about the lever arm that a 100mm long stem creates on the steering tube or that the increased diameter and load bearing surface of spacers around the steering tube will increase its stiffness ...


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## Ben Bravis (Jul 6, 2015)

I took my spacers off the top VERY quickly after I impaled my jewels on them while going OTB....

Sent from my XT1080 using Tapatalk


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## noose (Feb 11, 2004)

jacksonlui said:


> I asked a builder and he said Fox recommends a max of 40mm spacers. I put 45mm in mine only because I didn't have spacers that added up to 40mm. I like a longer stem to allow for flexibility in riding position as well as resale value.


I completely agree. If I'm riding steep descents I want to be able to put spacers under my stem to raise my bars. Resale value and stiffness are added bonuses.

Sent from my SM-G920W8 using Tapatalk


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## terrasmak (Jun 14, 2011)

Ben Bravis said:


> I took my spacers off the top VERY quickly after I impaled my jewels on them while going OTB....
> 
> Sent from my XT1080 using Tapatalk


I have 15mm on top and wonder if it to much


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## Ben Bravis (Jul 6, 2015)

terrasmak said:


> I have 15mm on top and wonder if it to much


I only had 20mm on at the time

Sent from my XT1080 using Tapatalk


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## ejewels (Jul 16, 2009)

manual63 said:


> As far as having them stacked a bunch below. If you are doing this, something isn't right. Frame is too small, bars are too low, and so on. If you need to run a bunch of spacers below, run a higher rise bar and reduce those spacers. Frames and headtubes are not designed to take the extra leverage of a stem way up in the air like that. All it does is weaken the steerer tube because it now has less support and stresses the headtube of the frame more.


Just found this searching around and figured I'd bring it up for any beginners wondering about proper spacer amounts. The correct answer is however many you need to get the right fit.

Many modern geo bikes now come with lower stacks, so my bike that fits me and my super long legs, I need all the spacers under the stem. So saying "something is wrong" is not true at all. I was fit by my LBS on the MTB AND my road bike too. Using all the spacers that ships with the bike doesn't mean the bike is too small. Look around at a group ride and I guarantee you'll see many that kept all the spacers on when they bought it. If I sized my MTB's by that, I'd be on a XXL at 5'9".


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## TwoTone (Jul 5, 2011)

ejewels said:


> Just found this searching around and figured I'd bring it up for any beginners wondering about proper spacer amounts. The correct answer is however many you need to get the right fit.
> 
> Many modern geo bikes now come with lower stacks, so my bike that fits me and my super long legs, I need all the spacers under the stem. So saying "something is wrong" is not true at all. I was fit by my LBS on the MTB AND my road bike too. Using all the spacers that ships with the bike doesn't mean the bike is too small. Look around at a group ride and I guarantee you'll see many that kept all the spacers on when they bought it. If I sized my MTB's by that, I'd be on a XXL at 5'9".


Gee your word or the manufacturer's? Gee decisions decisions.

I think I'd follow this warning from Fox's website:
WARNING: Never use more than 30 mm of height of steerer stem spacers under the steerer stem, as this condition can cause the steerer tube to fail prematurely, causing a loss of control resulting in SERIOUS INJURY OR DEATH.


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## mack_turtle (Jan 6, 2009)

Steerer tube material is one limit. Carbon and alu steerers will require few spacers than a steel one. Look at the tower of spacers people put on Long Haul Truckers and the like.

I would rather have a tall stem or riser bars than a big ol stack of spacers any day. Better yet, a frame that's made with a well thought-out design that makes a ludicrous stack unneeded.


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## ejewels (Jul 16, 2009)

TwoTone said:


> Gee your word or the manufacturer's? Gee decisions decisions.
> 
> I think I'd follow this warning from Fox's website:
> WARNING: Never use more than 30 mm of height of steerer stem spacers under the steerer stem, as this condition can cause the steerer tube to fail prematurely, causing a loss of control resulting in SERIOUS INJURY OR DEATH.


so you're saying new bikes that are shipped with all the spacers under the stem is going against this? That would be a huge legal issue and danger. Think about it. Guy buys bike and leaves spacers on (majority of people). He is now going against the mfgs requirements? Seems to me the bike wouldn't be sold ghat way if it was wrong.

Common sense.


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## ejewels (Jul 16, 2009)

I should also mention that my bike came with 3cm of spacers under the stem and that's what I run. If that's extreme and wrong than many bikes on mtbr are wrong.

Also, the point of my post was to say that having more spacers under the stem doesn't necessarily mean the bike is too smal like the one poster suggestedl. Case in point, long legs and the rider doesn't want a lot of saddle to bar drop.


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## ghoti (Mar 23, 2011)

On top of the stem doesn't really matter. Supposedly it's the force from the handlebars/stem that puts stress on the steerer tube and can cause it to fail right underneath the stem. Fox and RS say no more than 30mm under the stem.


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## TwoTone (Jul 5, 2011)

ejewels said:


> so you're saying new bikes that are shipped with all the spacers under the stem is going against this? That would be a huge legal issue and danger. Think about it. Guy buys bike and leaves spacers on (majority of people). He is now going against the mfgs requirements? Seems to me the bike wouldn't be sold ghat way if it was wrong.
> 
> Common sense.


Which bikes are shipping with more than 30mm under the stem?

As mentioned on top is fine. I actually run a few extra on top to keep my steerer tube longer for flexibility and resale value.


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## TwoTone (Jul 5, 2011)

ejewels said:


> I should also mention that my bike came with 3cm of spacers under the stem and that's what I run. If that's extreme and wrong than many bikes on mtbr are wrong.
> 
> Also, the point of my post was to say that having more spacers under the stem doesn't necessarily mean the bike is too smal like the one poster suggestedl. Case in point, long legs and the rider doesn't want a lot of saddle to bar drop.


The correct way to fix that is with a rise in the stem or riser bars, not more spacers.


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## ejewels (Jul 16, 2009)

OK, but you're saying above 30mm (or what the bikes ship with) correct? In other words if you need more than about 30mm... you need to do that with rise in handlebars and stem?

I was on my phone typing fast but the only reason I posted and revived this thread was to say that using the stock number of spacers (usually about 30mm on modern bikes) doesn't mean the bike is too small as one poster hinted at. Now, I could be wrong and maybe he was referring to an excessive amount of spacers under the stem... but a normal amount that comes with the bike doesn't mean the bike's too small or there is an issue.


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## TNTall (Nov 7, 2016)

futurerocker1 said:


> right now I currently have 4 10 mm spacers, 3 below stem and one above. I was thinking about trying 2 on top.. but this would have looked goofy. How many spacers do you run? how many is safe/recommended?


The Rockshox Pike manual says 30mm spacer max below the stem too. I'm glad this thread came up because I'm putting a new fork on and was thinking about using more spacers and going with a flatter bar. Now I think I'll stay with a riser bar.

I don't like spacers above the stem either. I took a chunk out of my knee with that.


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## TwoTone (Jul 5, 2011)

ejewels said:


> OK, but you're saying above 30mm (or what the bikes ship with) correct? In other words if you need more than about 30mm... you need to do that with rise in handlebars and stem?
> 
> I was on my phone typing fast but the only reason I posted and revived this thread was to say that using the stock number of spacers (usually about 30mm on modern bikes) doesn't mean the bike is too small as one poster hinted at. Now, I could be wrong and maybe he was referring to an excessive amount of spacers under the stem... but a normal amount that comes with the bike doesn't mean the bike's too small or there is an issue.


He was referring to stuff like this which was already posted earlier.


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## ejewels (Jul 16, 2009)

ah ok... my bad.


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