I've read some posts that at least one spacer is required on top of your stem. Other posts said it was bike dependent. I have an old trek 5000 ... Do I need to keep a spacer on top of the stem or could I raise the stem all the way up?

I've never heard of a requirement for a spacer. Assuming you're referring to a threadless headset, the primary rule is the top of the stem or spacer needs to be about 3mm above the top of the steer tube. You can achieve that 3mm gap by stacking spacers below or above the stem. Or you can cut the steer tube.

See middle of the article: https://www.parktool.com/blog/repair...ion-threadless

What I have read and seen on-line: For carbon steerer tubes, the top of the tube should be no lower than the top of the stem clamp. This avoids asymmetrical forces on the fragile carbon steerer tube as one tightens the stem bolts and which could crush the end of the tube. A spacer keeps the end cap from touching the top of the compression bolt cap; if they did touch, it would be difficult if not impossible to secure the steerer tube inside the headset.

Yes, you are correct, for carbon steerer tubes! The above mentioned Park Tool article says "When dealing with a carbon steerer tube, it is critical to have the steerer tube go all the way through the stem, in order to reduce stress on the end of the steerer tube. It is then necessary to have a spacer on top of the stem."

Having the steerer long enough to need a spacer above the stem is a real good idea for future fitting options, independent of steerer material. All my threadless bikes have this and they are all steel steerers. Andy

Ten days ago I purchased a new Cervelo Aspero from my LBS. I asked them to swap the Easton EA50 stem that came with the bike for a shorter one, but they would only do it if I paid full price for it (no credit for the perfectly new OEM stem already on the bike). A bit miffed at this, I declined and bought myself a new Easton EA70 stem on line and installed it myself. What I found when I swapped the stems is that the shop had cut the carbon steerer tube too short. The top of the steerer tube was about 8 mm below the top of the stem clamp. That's not a good thing with carbon tubes, The only way to correct this is to remove a few spacers from below the stem (there were no spacers above it - the top cap was installed directly on the top of the stem) but this would, obviously, lower my stem by about 1 cm.

Normally I wouldn't care, but I bought the bike because it fit me just right. With a lower stem - not so much. I don't want or need to be that low. This is a gravel bike, not a racer.

When I took the bike back to the store today the owner was there, and he acted like I was crazy. I showed him the Enve Composites video on their YouTube channel that recommend exactly what I was telling him (put a spacer above the stem, avoid clamping on a carbon steerer tube that is beneath the top of the stem clamp) but he didn't care.

I just cannot win.

If your EA70 is a current model, it can be run as either +7º or -7º. If you currently have it set as -7º, you can flip it, and would need to remove a handful of spacers to get it back to the same height.

The trusty Stem Comparison Tool will help you.

Carbon steers need it ,

Metal you put a spacer over the stem to lower the bars , knowing when you are old you might want them higher again,
so don't cut it down,,

Because, you realize, it won't grow back..






...

Unless you have the very rare, not-listed-in-the-catalog, Park STS-1 Steerer Tube Stretcher. But you'll need to go to a 1" threadless headset, since the steerer tube gets thinner as it gets longer. (If the bike was 1", you have to go French.)

--Shannon

I'm actually running -17. Was plus 17 but a bike fitter asked me to lower the front. I obviously did a huge change ... It's been better than before but I've been wondering if a slightly in between configuration works best hence the thought of bringing down that top spacer to lift just a bit. The alternative would be a new -7 stem

Oh wow ... I would fight back because that's just reckless / irresponsible. A Google review can go a long way. Tell him you will report him to the bike manufacturer or some regulating authority and do so ...

If the steerer is carbon you have to put a spacer on top and the steerer should be cut slightly above the stem.

If the steerer is metal, you don't need a spacer on top.

With CF steerers, it depends. For instance, Cervelo explicitly states not to put any spacers above the stem, and that the top of the steerer should in fact be 3mm below the top of the stem.

Is that on their US website? Because I searched and searched and could not find any statement to that effect. I have sent them a query via their on-line customer service form, but have yet to heard back.

I'm imagining all the non-C&V folks wondering "go French? "

How fast can an escargot ?

That’s from the manual that comes with the bike, with the instructions on how to cut the steerer and glue in the aluminum sleeve. I’d get a photo of it, but I’ve no idea where it is, as I glued in my sleeve back in 2017. Same stem has been on there, 3mm above the top of the steerer, for ~13k miles.

Idunno, what's a grecian urn?

https://en.wikipedia.org/wiki/Aristotle_Onassis

I like having a small spacer above the headset just in case I want to move up a touch. Not always needed aside from on carbon steerer tubes.

Found it, on line/. Thanks.

For whatever reason Cervelo mandates that the top of the carbon steerer tube be 4 mm below the top of the stem. Everything that I've recently read about carbon forks says the opposite: don't clamp a steerer tube above the tube's top edge. I wonder what's so different about Cervelo fork tubes from the Enve, Specialized, Cannonade, etc tubes...

That seems to me like an exception to the rule. Maybe Cervelo manufactures steerers differently, I don't know.

All bikes I've seen and had with carbon steerers had a spacer on top and the manual stated it was mandatory.

I am very surprised that some forks do not allow a spacer above the stem.That would be a total deal breaker for me.

I favor the way Cervelo does it-- the aluminum glue-in insert is over 3" long, so no matter where the stem is on the steerer, it's fully supported. If someone is running a wedge expander with a spacer above the stem, maybe the wedge is supporting the whole stem, maybe it isn't.

Aesthetically, I don't care for a spacer above the stem at all. Looks unfinished.

My 2020 Cervelo Aspero does not have a glue-in insert at the top of the head tube- it has an aluminum expander... So I was a bit confused reading the Cervelo on-line assembly instructions mentioning the insert and careful application of glue, but no mention of an expanding aluminum wedge with a Allen bolt at the top into which the top cap screw inserts.