Rims

MTB Rim Buying Guide

The rim determines tyre profile, wheel stiffness, weight and durability. It's also the component most likely to need replacing on a wheelset — hubs last years, spokes rarely break, but rims take direct impacts and eventually dent, crack or wear out.

Internal Width

Internal width (measured between the bead hooks or bead seats) determines how the tyre sits on the rim. Wider rims spread the tyre for a squarer profile with better cornering support. Narrow rims give a rounder profile. Guidelines: 25-28mm for XC (2.0-2.3" tyres), 29-32mm for trail/enduro (2.3-2.6"), 33-35mm for plus/gravity (2.5-2.8"). Running a tyre that's too narrow for the rim or too wide for the rim creates a poor tyre profile and can affect bead retention.

Alloy vs Carbon

Alloy rims (6061 or 6069 aluminium) dent on hard impacts but don't catastrophically fail — a dented alloy rim is ugly but often still rideable. They're cheaper, easier to true after impacts, and the practical choice for aggressive riding on rocky terrain. Carbon rims are lighter (100-150g per rim), stiffer laterally, and can be made wider without the same weight penalty. But carbon fails differently — instead of denting, it cracks, and a cracked carbon rim is scrap. For UK trail centres and enduro, alloy is the pragmatic choice. For XC racing and lighter trail riding, carbon makes a strong case.

Spoke Count and Drilling

28-hole rims suit XC and trail — lighter, adequate strength for most riders. 32-hole rims suit enduro, DH and heavier riders — more spokes distribute the load and handle impacts better. The spoke count must match your hub — a 32-hole rim needs a 32-hole hub. Some rims are offset-drilled (spoke holes shifted to one side) to help equalise spoke tension on the rear wheel, where the drive side spokes are significantly shorter than the non-drive side.

Tubeless Compatibility

Most modern rims are "tubeless ready" — the rim bed is designed to seal with tubeless tape and hold a tubeless tyre bead securely. Look for hooked or hookless bead designs. Hooked beads are the traditional design and work with all tyres. Hookless (Stans and some carbon rims) are lighter but only compatible with tyres rated for hookless use — check before buying. Some older rims aren't tubeless-compatible regardless of tape — if the rim bed has large spoke holes or an uneven channel, tubeless may not seal reliably.