Spacers above stem

jd843

Hi

I bought a Deda Zero1 stem and was reading the manual on how to install it when I came across something that confused me. It says to not use spacers above the stem, because this means the lower stem bolt will exert pressure on part of the steerer that isn't supported by the fork bung. It also says that the top of the stem should be 2-3 mm above the top of the steerer.

I get the logic in this explanation, but what confuses me is that I've read elsewhere that you should always have a spacer above your stem so that the top bolt of the stem clamp doesn't crush the top of the steerer. This also sounds sensible to me, but I can't seem to find a consensus on which is right - spacer or no spacer?

My bike came with a 5mm spacer above the stem and 3 × 10mm spacers below it. I'm guessing it's safe to assume that this setup is okay with my new stem since the shop built it this way (the stem stack heights are the same)?

Thanks

g00se

I would go with whatever the fork manufacturer recommends - not the stem manufacturer. And with neither available, I would add a spacer above the stem if it's a carbon steerer.

slowbike

really does depend on the steerer material.
If it's alloy then it doesn't matter. If it's carbon then you need the bung inside to be at the same height as the stem.

Without knowing your bike - it will most likely be fine to replace the stem in exactly the same place as the current one is installed - assuming it was installed by the shop or someone else competent.... !

keef66

My Scott frameset came with an expander bung which when properly inserted sits ever so slightly proud of the top of the steerer. No danger therefore of crushing the top of the steerer tube.

Scott's instructions say no spacers above the stem, presumably to avoid clamping forces below the part of the steerer supported by the bung.

sungod

i'm sure the intent of the deda instructions is don't put a tall spacer above the stem

it's ok to use a short one to allow a smidge of steerer above the stem and clear the end of the bung and/or stop the top cap fouling

i use a 3mm spacer for this

Paul 8v

I always go with a 5mm spacer as per "the rules" apparently this also means the stem gets a decent contact patch on the steerer too

Secteur

I have a couple of spacers above my stem (all carbon set up) because I haven't ever got around to having the excess steerer tube cut down*, but I was very careful to buy an aftermarket bung where the bung was at the same level as the stem clamp points, so I feel safe despite having (I think) 20mm or so of spacers up top, despite cannondale saying absolutely never to do this (with their standard bung).

In other words, do what you want so long as your internal bung is exactly where the stem clamp point is, to prevent the steerer being crushed.

2 years on all seems to be ok.

*it doesn't look awful, but I really do need to get this done!

OnTheRopes

Im pretty sure it does not mean you cannot put spacers above the stem, it almost certainly means do not allow a spacer to be above the top of the fork tube or else it will not tighten correctly.