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Is there a big difference between having like a few spacers on top of the stem and then a few on the bottom compared to placing all of them at the bottom?

Or is this just personal preference.

Asking because on one of my flat bar bikes, the stem cap when screwed in always scraps off the paint of the stem which makes it look kinda uneven.

Thanks in advance! :D

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  • Adjusting handlebar height and to a lesser degree, the reach, to fine tune the bike fit are reasons to use spacers below the stem. Putting the removed spacers above the stem preserves the stack measurement then the steer tube length can remain the same while one experiments with bar height. Most fork manufacturers advise a maximum amount of spacers that should be used below the stem. Thirty millimeters is a common limit. Five to 10mm above is sound mechanically and aesthetically. More than that above after fine tuning the fit is less than aesthetically pleasing (opinion)
    – Jeff
    Nov 18, 2022 at 5:02

2 Answers 2

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The primary difference is the height of the bars. Setting that to match your preferred fit should be what drives your decision here.

Some manufacturers of forks with carbon steerer tubes recommend that you allow for a 5-mm spacer above your stem.

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  • I think I've heard up to 10mm. That is related to carbon steerer tubes; you want the expander plug to sit along the area where the stem is clamping the steerer. That's described in @jayded-bee's answer.
    – Weiwen Ng
    Nov 5, 2022 at 12:11
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If the steerer is carbon then you need to assure the expansion plug is long enough to reach from the top of the steerer to below the bottom edge of the stem.

If your plug is too short to provide for this then riding with too many spacers above the stem might be dangerous as the steerer could break.

The solution then would be to buy a plug that is long enough.

If the steerer is metal then this does not apply as the expansion plug is replaced with a star nut.

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  • Generally, I think mechanics and manufacturers are probably comfortable with 10mm of spacers above the stem.
    – Weiwen Ng
    Nov 5, 2022 at 12:11
  • @WeiwenNg Manufacturers have been known to be comfortable with setups that are not safe for the riders. The justification that manufacturers do things is no longer enough in my eyes.
    – jayded-bee
    Nov 6, 2022 at 17:18

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