WTB has updated its premium mountain bike rim offering with some new carbon hoops.

Read more: Best mountain bike wheels in 2021, aluminium and carbon options

The Californian brand’s rims and are factory fitted as original specification on many brands and for the 2021 model year, there are two new lightweight composite options.

Prototyping and validation testing saw WTB engineer spending a year on pre-production 2021 carbon rims, to ensure they are tough enough. The result was a redesigned CZR carbon rim.

The new CZR product line is optimized for a combination of low mass and reliability. One of the most notable features is those 4D angled spoke holes, which are distributed in an asymmetric pattern, to allow wheel builders the best possible tension structure.

WTB is producing its new CZR carbon rim in two internal widths: 23- or 30mm. Although the i30 rims are completely on trend for enduro and trail riders, where 30mm internal diameter rims are now the standard, the i23 might be considered a touch too narrow.

Most carbon XC wheelsets have trended to 25mm as the minimum width requirement, especially when mounting the latest 2.4” fast-rolling tyre options. For gravel riders, the i23 will be an excellent option.

Spoke counts for any enduro build

In terms of spoke and weight specification, the i23 is credibly light. It is mass rated at only 331g and with a 24h spoke pattern, you can build a CZR rim wheelset that has very low rotational mass.

For trail and enduro mountain bikers, the CZR i30 rim weighs 472g with 28h spoke count, or 484g if you need 32 spokes for that overbuilt rear wheel on a long-travel bike.

WTB claims that during its exhaustive schedule of trail testing, not a single CZR pre-production rim was cracked or deformed. These new CZR carbon rims also feature the company’s TCS 2.0 system, featuring a solid strip integration of its rim bed, below the tubeless tape. This makes everything about tubeless a lot easier, and retains tyre pressure, even if you do manage to break a spoke.