MTB Headset Spacers

How to choose your MTB headset spacers

Headset spacers slide onto the fork steerer tube, below or above the stem, and determine handlebar height. It is the cheapest, quickest and only fully reversible position adjustment.

The diameter

1"1/8, or 28.6 mm, on almost all mountain bikes — including forks with tapered steerers, where only the base is 1.5". Any doubt only applies to very old MTBs with a 1-inch steerer.

The thicknesses

• Kits combine spacers of 2.5, 5, 10 and 20 mm, which are stacked to achieve the desired height.
• Start by fitting everything below the stem, go for a few rides, then lower it in 5 mm increments.
• Keep the removed spacers : place them above the stem. This keeps the option to raise your handlebars without having to replace anything.

The golden rule

The fork steerer must end 2 to 3 mm below the top of the stem, never flush or above. This gap allows the top cap bolt to pull on the star nut and preload the headset bearings. Before cutting down any steerer, keep at least one 5 mm spacer above the stem: cutting is permanent, stacking is not.

Aluminium, carbon, colours

Machined aluminium covers every need and comes in various colours from Hope, Burgtec and Spank, matching your hubs or top cap. Carbon saves a few grams and complements a carbon cockpit. For this component, the difference is far more aesthetic than functional.

To find out more: How to choose your MTB top cap, star nut and spacers

See also: Top caps and star nuts · MTB Stems · MTB Headsets