Why using this small spacer on the top of the stem (Team Emirates)?

[tmr5555]

It's because they all get toghether while building the bikes at the beginning of the year, All the mechanics, people from colnago, etc...
Basically if they do it, it's good to go. I'd replicate it no questions asked

[wheelbuilder]

I prefer the look of flush, but always use one above stem to ensure no fouling. If you are flexible enough, none below stem is always the rule.

[TonyM]

My current setup: also with the 5mm spacer on top.
I would however prefer to have it without.
Superleggera stem, 110mm; C60 48S

[Valbrona]

I use a 2.5mm spacer on the top. This does require the steerer to be cut flush to the top of the stem. For me it’s good enough safety wise and it looks better than a 5mm spacer.

A spacer on top of a stem is my my preffered arrangement, but the spacer should always fit on a protruding steerer tube rather than flush on the stem. This is because the spacer is susceptible to being knocked if you crash or your bike topples over. If the spacer is dislodged, well then so is the top cap and this can have the effect of dislodging the bung inside the steerer and possibly damaging the steerer.

"It looks better" philosophy is not very clever when it comes to bikes, or life.

[AJS914]

These 3mm Ritchey spacers are nice. They look a little nicer than the 5mm spacer on top.

[Nefarious86]

Whoops haha

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[themidge]

+1 about 3mm (or 2.5mm in my case), they do the same job as a 5mm one, but look better because of the lower stack. Its lighter too .

[pdlpsher1]

I use a 2.5mm spacer on the top. This does require the steerer to be cut flush to the top of the stem. For me it’s good enough safety wise and it looks better than a 5mm spacer.

A spacer on top of a stem is my my preffered arrangement, but the spacer should always fit on a protruding steerer tube rather than flush on the stem. This is because the spacer is susceptible to being knocked if you crash or your bike topples over. If the spacer is dislodged, well then so is the top cap and this can have the effect of dislodging the bung inside the steerer and possibly damaging the steerer.

"It looks better" philosophy is not very clever when it comes to bikes, or life.

I said the steerer is cut flush. The steerer expander sits on top of the steerer. So the 2.5mm spacer can’t go anywhere and it can’t get knocked out of position. To get the precise steerer length I use a finishing sander to sand down the carbon steerer. My setup is safe as 100% of stem clamp is clamping on the steerer. If someone prefers the steerer to be 2mm longer than the stem that is fine too. Whatever floats your boat. Will post a pic of my setup later.


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[guyc]

"It looks better" philosophy is not very clever when it comes to bikes, or life.

No, but "It looks better and it's just as safe" is pretty much ok.

[pdlpsher1]

Oops. I had thought I have a 2.5mm but it’s a 5mm. I was looking for a 2.5mm but the spacer I like (Point One Racing) only has a 5mm. My bad.






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[wilwil]

I think this has been suggested by bike manufactures, besides stem suppliers such as Deda.

Here is what Bianchi said for instance.

https://www.bianchi.com/global/news/new ... ty-warning

Bianchi has recently learned that stem assembly's on some bicycles with a full carbon steerer tube may have been incorrectly assembled with spacers above the stem totaling more than 5 mm. Bianchi is requiring all consumers that are using bicycle stem assembly's with this configuration on a full carbon fork to immediately stop using your bicycle and inspect your fork for damage and proper installation.

Why would a possible wear or cut mark from the lower edge of the stem only be there if the stem had had spacers of more than 5mm above it?

[guyc]

Mine is now flush as I prefer it having had the steerer cut down to its final length today

[Calnago]

I think this has been suggested by bike manufactures, besides stem suppliers such as Deda.

Here is what Bianchi said for instance.

https://www.bianchi.com/global/news/new ... ty-warning

Bianchi has recently learned that stem assembly's on some bicycles with a full carbon steerer tube may have been incorrectly assembled with spacers above the stem totaling more than 5 mm. Bianchi is requiring all consumers that are using bicycle stem assembly's with this configuration on a full carbon fork to immediately stop using your bicycle and inspect your fork for damage and proper installation.

Why would a possible wear or cut mark from the lower edge of the stem only be there if the stem had had spacers of more than 5mm above it?

It goes back to what was being said earlier... and relates to where the internal expansion plug ends up being. In lots of cases the expansion plug is quite short and is designed to be positioned in a very specific spot within the steertube, and most typically wants to support the lower bolt area and the lower edge of the stem where it meets the steertube. If you throw too many spacers above the steertube that means the expansion plug also is positioned higher (also depends on the plugs design as well). Thus it may provide an anchor to provide the preload on the headset still, but it no longer is providing the structural support that it is intended to provide. And every system is different these days, some don’t even use an expansion plug. Best advice if you’re not sure is to follow the manufacturers recommendations.
And again, it really depends on the design of the components you’re using. In the case of the Deda superlegerra stem, that top bolt is extremely close to the top edge of the stem. Therefore, I’d want the steertube to be at least almost flush with the stem top in order to ensure that calming force is not fully concentrated on the edge of the steertube. Trouble with that if you want a flush cap is that many caps have a lip that extends down a mm or two, and it could bottom out on some tops of the expansion plug, providing no space to get a proper preload, however slight it may be, on the headset bearings before locking things down. There are ways to do this, like temporarily placing a spacer on top simply to enable the preload adjustment, then removing it. But in general, it’s good to be able to apply the preload without your top cap bottoming out in the context of your final setup.
Trek/Bontrager has had some interesting designs over the years, but still recommend a spacer above the stem in all cases where a carbon steertube is used. And that includes cases where their integrated stem/bars are used. They also recommend at least one spacer between the bottom of the stem and the headset as well. Although, I’ve certainly seen cases of them omitting that bottom spacer on some of their pro Bikes, but I can’t recall any of their pro builds I’ve seen where they don’t have a 5mm spacer above the stem, regardless of bar/stem combo. Point is, be aware of what and why you are doing something and if at all in doubt, follow the manufacturers recommendations.

[wilwil]

I think this has been suggested by bike manufactures, besides stem suppliers such as Deda.

Here is what Bianchi said for instance.

https://www.bianchi.com/global/news/new ... ty-warning

Bianchi has recently learned that stem assembly's on some bicycles with a full carbon steerer tube may have been incorrectly assembled with spacers above the stem totaling more than 5 mm. Bianchi is requiring all consumers that are using bicycle stem assembly's with this configuration on a full carbon fork to immediately stop using your bicycle and inspect your fork for damage and proper installation.

Why would a possible wear or cut mark from the lower edge of the stem only be there if the stem had had spacers of more than 5mm above it?

It goes back to what was being said earlier... and relates to where the interenal expansion plug ends up being. In lots of cases the expansion plug is quite short and is designed to be positioned in a very specific spot within the steertube, and most typically wants to support the lower bolt area and the lower edge of the stem where it meets the steertube. If you throw too many spacers above the steertube that means the expansion plug also is positioned higher (also depends on the plugs design as well). This it may provide an anchor to provide the preload on the headset still, but it no longer is providing the structural support that it is intended to provide. And every system is different these days, some don’t even use an extremely an expansion plug. Best advice if you’re not sure is to follow the manufacturers recommendations.

I understand that, but how deep the plug goes won't effect cut marks happening on the outside face of the steerer as mentioned in the Bianchi warning. I have seen such marks and put it down to over sharp edges on stem or spacers.
Cutting the steerer as short as possible makes the frame much harder to sell or adjust if you need to change your position. I usually have 10-15mm spacer above and make sure the bung is deep enough. Doesn't look as nice though. Canyons and C59s came with Acoss headsets that have no bung.

[rgamble]

Lets say for whatever reason the steertube is cut even with the top of the stem, you want the top cap to sit flush & you want peace of mind.

When setting the preload sit a 5mil spacer on top, do the adjustment, tighten the stem bolt(s), remove to spacer, and place the top cap.

A thin cap like Extralight (with a hollow 3mil titanium bolt) works well.