Headset spacers

What headset spacers are for

These are the rings stacked on the fork steerer, below or above the stem. They adjust the handlebar height — and therefore your riding position — and ensure the steerer does not protrude above the stem, which is essential for proper clamping.

The height

They are sold in 3, 5, 10, 15 and 20 mm, usually in sets so you can achieve the exact height you need. Moving a 10 mm spacer from below the stem to above it lowers the handlebar by the same amount: it is the simplest way to lower your riding position gradually before considering a stem with a steeper downward angle.

The rule to remember

You need to keep 3 to 5 mm of spacers above the stem so the top cap can preload the headset. And once the steerer has been cut, you cannot raise it again: you can always lower it, but never raise it. Before cutting a new steerer tube, ride for a few weeks with the full stack of spacers in place.

Aluminium or carbon

• Thealuminium is the standard choice: inexpensive, resistant to deformation and available in every height.
• The carbon matches the look of a carbon steerer and saves a few grams. Its appeal is mainly visual.
• Choose the diameter to match the steerer: 1"1/8 (28.6 mm) in the vast majority of cases, or 1"1/4 on some frames.

Profiled spacers: a category of their own

Many of the products here are not round. Cockpits with internal routing — Deda Alanera RS and Superbox, Vision ACR and Metron 5D/6D, Ritchey Switch, Cane Creek HCR — use profiled spacers, sometimes split, that allow cables and hoses to pass through. They are specific to a system : no standard round spacer can replace them, and there is no generic equivalent.

Before you order

Check whether your current spacers are round or profiled, measure the total height of the stack and note the diameter. With an integrated system, start with the handlebar or stem brand: that determines which part you need, not the frame.

To find out more: How to adjust your position on a road bike

See also: Road bike stems · Top caps and expanders · Road bike headsets and bearings