Run-of-the-mill stem option from the headset giant.
Since we stopped using the best mountain bike stems as a way of compensating for tiny bikes, they have become shorter and more focused on handling. Most of the stems I see on test rigs and other riders’ bikes are typically around 35 to 50mm in length. This explains why the Stealth stem from Acros is available in six different lengths, but Oxford Products only brings the three shorter sizes into the UK. Which makes sense as I can’t imagine anyone would be interested in a 90mm stem these days.
Physically the Stealth is a lot like the Race Face Turbine R in terms of shape and dimensions, but there are a couple of key differences. The Stealth is £10 cheaper, but it’s made from 6082-T6 aluminium rather than 7075 aluminium. The latter has greater tensile strength and fatigue life, but we’re splitting hairs really – the Stealth is plenty strong and durable enough. Where it does fall down slightly is in the design of the face plate. Race Face uses an Overbite face plate on the Turbine R, which is where the gap on the upper part of the clamp is closed fully and then you just nip up the bottom two bolts. This puts less stress on the fasteners, reduces the risk of tightening the face plate off centre and also closes the gap, which from a cosmetic point of view just looks better.
If you’re methodical, you can tighten the cro-mo steel bolts on the Stealth evenly, but you might want to add a drop of a medium strength thread locker such as Loctite 243 to the threads before fitting because they don’t come with any. That way you won’t have to exceed the standard torque setting, plus it also stops the bolts corroding and possibly seizing.
The Acros Stealth is a solid stem and it’s nicely machined with radius edges on the face plate and stem body, which stops it scuffing the bar during fitting. I just don’t think it’s as polished a design – you can see the bolt threads in the gap at the top and, if you’re running a coloured handlebar, that too. The Stealth is slightly more affordable than the Race Face Turbine R but you don’t get a choice of nine colours or a stubby 32mm option.