# Do you put a spacer on top of your stem?



## baker921 (Jul 20, 2007)

I believe the idea is to prevent ovalising the top of your fork steerer when tightening the stem bolts. I don't think new bikes usually come this way.


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## Kristatos (Jan 10, 2008)

I think the only reason to leave space there now is if you're still fussing with the setup or may want to move the stem up higher in the future. I used to leave some extra steerer on my MTB when I did more aggressive riding and would raise the bars for the occasional bike park trip, but now that I ride XC exclusively I just dropped the bars and cut the steerer down.


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## rx-79g (Sep 14, 2010)

Same discussion going on right now:

http://forums.roadbikereview.com/showthread.php?p=3131270#post3131270

Spacers on top can be a good structural idea, and many bikes either come with them, have the stem on the highest setting which is moved down by moving some spacers on top, or have an uncut steerer. Some systems specify not using them.


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## MisterMike (Aug 12, 2004)

I've seen it more as a topic with carbon steerers for sure. You may want to read this Q&A from velonews. The logic seems sound to me and Zinn usually gets his facts straight. 
http://velonews.competitor.com/2009/08/technical-faq/technical-faq-spacers-above-stems_101038


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## PJ352 (Dec 5, 2007)

MisterMike said:


> I've seen it more as a topic with carbon steerers for sure. You may want to read this Q&A from velonews. The logic seems sound to me and *Zinn usually gets his facts straight. *
> http://velonews.competitor.com/2009/08/technical-faq/technical-faq-spacers-above-stems_101038


But not always. As noted in the thread rx-79g links to, Specialized and Cannondale (to name two) do NOT recommend a spacer atop the stem. Another member mentioned Giant TCR's, but I can't verify that.


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## frdfandc (Nov 27, 2007)

Spacer goes on top of the stem when its recommended by the manufacturer. Other wise, no.


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## MR_GRUMPY (Aug 21, 2002)

I've got a 3mm spacer on top of my stem because I'm too lazy to cut the stearer tube again. (non-carbin)

I'd put it under my stem, but spacers under your stem are for sissies.


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## rx-79g (Sep 14, 2010)

frdfandc said:


> Spacer goes on top of the stem when its recommended by the manufacturer. Other wise, no.


No? Why not?


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## Richard (Feb 17, 2006)

On a carbon steer tube, it's never a bad idea to have at least a few mm of spacers above the stem. Put your fingers around an empty toilet paper carboard tube. It's a lot easier to compress it at the top than it is a few mm down.


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## rx-79g (Sep 14, 2010)

Richard said:


> On a carbon steer tube, it's never a bad idea to have at least a few mm of spacers above the stem. Put your fingers around an empty toilet paper carboard tube. It's a lot easier to compress it at the top than it is a few mm down.


Well, it's a bad idea if you aren't supposed to because of the way the fork or plug is made and the instructions tell you not too.


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## kbiker3111 (Nov 7, 2006)

Richard said:


> On a carbon steer tube, it's never a bad idea to have at least a few mm of spacers above the stem. Put your fingers around an empty toilet paper carboard tube. It's a lot easier to compress it at the top than it is a few mm down.


How is this any different from an aluminum steerer tube? If anything the Al tube is thinner and more likely to buckle.


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## laffeaux (Dec 12, 2001)

Yes, I always put a spacer on top.
- It lets me raise the stem if I choose to: due to injury, time of year, or lending the bike to a friend I may raise the stem.
- A fork with a longer steerer can be more easily moved to a different bike in the future. A few frame does not always require a new fork.
- it gives the stem a better grip on the steerer.

There is no downside to leaving it longer.

When I first switched to threadless steerers on mountain bikes, I would cut the steerer to be 2-3mm below the stem. After doing this a couple of times I realized that it was a mistake. It limits the use for the fork - you can't make the steerer longer in the future, so why make it as short as possible?


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## looigi (Nov 24, 2010)

Just got two high end bikes and they both have 5mm spacers on top of the stem. Trek builds their bikes that way, Specialized doesn't.

I see all good and nothing bad in having the steerer extend a bit past the stem and having a spacer above stem.


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## jhamlin38 (Oct 29, 2005)

i have a small spacer on top of my stem and now I ride way, way faster. its added sensational vertical compliance.


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## rx-79g (Sep 14, 2010)

kbiker3111 said:


> How is this any different from an aluminum steerer tube? If anything the Al tube is thinner and more likely to buckle.


Carbon fiber is not as strong as aluminum in all directions. Fiberous materials are not very crush or impact resistant, nor are they hard.

Every aluminum steerer I've seen is quite thick - thicker than the center of a handlebar, for instance.


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## rubbersoul (Mar 1, 2010)

why yes


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## kbiker3111 (Nov 7, 2006)

rx-79g said:


> Carbon fiber is not as strong as aluminum in all directions. Fiberous materials are not very crush or impact resistant, nor are they hard.
> 
> Every aluminum steerer I've seen is quite thick - thicker than the center of a handlebar, for instance.


0_o

I'm looking at a carbon fiber fork and aluminum fork right now and the CF has a thicker steerer by far, but maybe its just this one.


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## bikerjulio (Jan 19, 2010)

laffeaux said:


> There is no downside to leaving it longer.


On my last build, I went on a trip before cutting the steerer, leaving 2cm on top.

Had a little accident when my foot came unclipped and I went down into the bars. Steerer stabbed me in the liver, leaving a nice bruise. :cryin: 

It is now cut down.


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## rx-79g (Sep 14, 2010)

kbiker3111 said:


> 0_o
> 
> I'm looking at a carbon fiber fork and aluminum fork right now and the CF has a thicker steerer by far, but maybe its just this one.


I didn't say the aluminum is thicker than the carbon - it shouldn't be. Metals are denser than most composites, and stronger by volume.

I said that the aluminum was rather thick, for an aluminum part.


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## Stogaguy (Feb 11, 2006)

*Perfect!*

I run a spacer on top of my stem for the same reason.


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## roadie01 (Apr 13, 2010)

*Spacer on top of the stem*

As this thread has already stated this is a matter of varying opnion. First and foremost I would recommend sticking with the manufacture's recomendation to avoid future warranty issues should the steerer fail. 

If you read the articles on steer tube failures and Trek's response it makes sense why they would run a 5 MM spacer on top of the stem. Trek obviously recomends using a Bontrager stem with thier bikes and state that other companies hollow out two much of the stem where it clamps the steerer causing uneven clamping forces and stress points. 

My advise as a ex LBS mechanic is:

Always use a torq wrench when tighting any thing carbon related (stems, bars, seat posts, etc..) 
Use carbon friction paste to avoid sliping 
Run a 5MM spacer on top of your stem for adjustibility and to insure the stem has a 100% purchase on the steerer at the point in which it clamps.
Use an internal compression nut that provides 360 degrese of support to the inside of the steerer and position it so that it is in allignment with where the stem clamps the steerer.


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## woz (Dec 26, 2005)

Obviously it's a good idea to follow the manufacturers recommendation, but that's assuming you are sticking with their recommended or approved parts as well. 

So while people are coming in on both sides nobody is really mentioning why this is so. Richard used the example of a toilet paper tube which is totally correct. It's much easier to crush a tube at the end than in the middle. But that's not taking all the factors into account. The type and size of the expander used in the steerer tube. So if you have a low height expander it doesn't reinforce the length of the stem you'd of course want to get the expander in the middle of the stem and leave steerer tube above the stem. However if your expander reinforces from top down then you may not want to leave spacers. For example if your expander is 4cm long and the clamp height of your stem is also 4cm then a flush cut steerer would allow the expander to reinforce the stem for the full length of the stem. However if you cut the steerer 5mm long then it would lift the expander so the bottom 5mm of the stem is not reinforced. 

So with all stock/recommended parts use manufacturers recommendation. However if changing expanders, stems, etc... take a look at what you have to figure out what is the best way to reinforce the steerer to prevent cracking.


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