Made to match Chromag’s 35mm diameter bars like the OSX, the BZA is a seriously chunky piece of kit. It’s fully CNC’d in Canada from aluminium billet, rather than being cold forged and then post machined.
- The best waterproof mountain bike jackets: top outer layers rated
- Buyer's guide to mountain bikes: get the best bike for you
- Seven trailside fixes every cyclist should know
The BZA uses thick M6 x 20mm steel Allen head bolts to secure both steerer tube and handlebars in place, and these round-headed bolts have smooth threads and have proven resistant to rusting after multiple winter rides and jet washes.
The BZA is at the heavier end of the weight spectrum for a stem suitable for trail riding, but the payback is an absolutely locked down, responsive steering feel and excellent stiffness.
Some fully CNC’d (rather than forged) aluminium stems can feel noticeably soft and twisty even in really stubby lengths, but the BZA is completely solid, and feels as precise as any other stem I’ve tried. This is likely in part due to the wide clamping area, the serious bolts and also the sheer thickness of aluminium in both the bar clamping zone and the stem’s interior.
One downside of the BZA is that at 178g, it’s over 50g heavier than the best stems that deliver equivalent stiffness and performance, and the £100 price tag is definitely at the boutique end of the price scale.
