Sidi Aertis review: a gravel shoe comfy enough for brief hike-a-bike sections, on-trend enough for ‘lit’ café stops

Let’s get one thing out of the way first. Sidi promotes this shoe as mountain bike attire – XC to be specific – but it’s just as capable as a gravel shoe, which is why you’ll find it gracing both sections of the brand’s website. So, if you see it elsewhere, described as the MTB Aertis, don’t worry; you’ve found the correct shoe, despite the ambiguous name.

In fact, Sidi also makes a near-identical shoe for roadies, called the Prima. The only difference is the sole – smooth and three-bolt ready on the Prima, vs knobbly and SPD compatible on the Aertis. If your road cycling is focused more on coffee stops than celerity, this shoe is the more satisfying solution for frequent café raids and the inevitable comfort breaks that follow. It’s the shoe I chose to wear when I crossed France earlier this year, which gives some insight into our itinerary.

Construction

Sidi has a reputation for making elaborate-looking shoes – its flagship Shot 25 model, for example, features a multitude of fabric panels, dials, and an externally adjustable heel retention system. In contrast, the svelte Aertis is noticeably minimalist.

A single large swath of suede-effect Politex material envelopes the top of the foot, augmented only by a Politex reinforcement patch on the toe box and a rubber backstay strip at the heel. The upper, which bears a single Sidi logo and a series of subtle stripes on the wrap-over closure, is perforated from heel to toe box for ventilation. Other than these modest embellishments, it’s completely unadorned. To further aid ventilation, the tongue is made from soft, cushioned, open-cell mesh.

A lightly padded collar and heel counter are upholstered in microfibre cloth of contrasting colour, in my shoes' case, a lemony yellow, which gives the relatively sombre khaki Politex upper a visual kick. It is, of course, the broad, vivid lime-coloured, mesh-like hook and loop strap that really pops. It’s a chief component of Sidi’s Firmor closure system, which the brand says provides superior lateral support and foot stability.

The upper closure features a rotary dial, not Boa’s ubiquitous Fit System, but Sidi’s own, proprietary Techno 3 alternative. Sidi’s tech, which first appeared in the late 1980s, predates Boa’s by at least a decade, and has advanced through several iterations since then. It differs from Boa’s dials in that it’s ratcheted closed via a little pop-up flap, and released by pressing two tiny tabs on each side of the barrel. Pressing each tab in turn micro-adjusts the closure tooth, by tooth. Additionally, Sidi’s laces are made from Dyneema, rather than coated steel, for lightness and flexibility.

The gloss black nylon sole has large sticky rubber tread blocks located at the heel and either side of the cleat channel. There’s also a smaller, replaceable, rubber tread block at the toe, and a large, rubberised Sidi logo running through the midfoot. Sidi rates the sole as six out of a possible twelve for rigidity, with five being the least stiff. I know, it doesn’t make much sense to me either, but suffice to say that while it’s quite possible to flex my size 48 shoes with my hands, flip-flops they are not.

The four two-bolt cleat mounting points have generous fore and aft travel, providing plenty of adjustment options. Sidi once had a reputation for setting cleat plates too far forward, but there’s ample opportunity here to get as much behind the pedal as you need.

Weight is a respectable 415g each in size 48. That’s a large size, so to bring some perspective, my similarly sized carbon-soled Shimano RX8 gravel race shoes weigh 325g each. However, they aren’t as comfortable or stable off the bike.

The Ride

The Aertis has been my go-to shoe for endurance and gravel rides this summer, both long, multi-day escapades and short evening dashes before sundown. All-in-all, I must have covered well over 2,500 miles wearing them, including the majority of outings on my XC bike – they really are that versatile.

Historically, Sidi’s fit has been notoriously short and narrow, issues addressed by its recently introduced Millennium last. Unfortunately, the Aertis’ last predates the Millennium, but I tend to size up by default, so, under normal riding conditions, my size 48s fit snugly, but comfortably enough. I did experience tightness across the forefoot as my feet swelled in the oven-like conditions of southern France, so a smidgen more space would have been welcome. Strangely, despite the discomfort, I don’t remember my feet feeling ridiculously hot during those 38°C Provençal afternoons, so the perforations in the upper and the mesh tongue must have been doing their job.

The sole is far from rigid, but that’s no bad thing for lively, explorative gravel rides, where a bit of unforeseen hike-a-bike is, in hindsight, rarely a surprise; and for long endurance rides that inevitably include at least one extended break for refuelling (aka lunch, for the non-cyclists among us). A little bit of flex helps tremendously with walking because it enables the foot to roll naturally and, more importantly, reduces the risk of suffering painful blisters induced by heel lift.

That said, my large feet don’t care for excessive flex because SPD pedals are too small a platform to support them unless the sole provides a stiff enough base to distribute the force on the downstroke. I believe Sidi has struck the right balance with the Aertis. I wasn’t overly aware of the small outline of the pedals pressing into my feet; I suffered no hotspots and never felt that the outer metatarsal area, which extends beyond the pedal body, was unsupported.

Grip from the soft rubber tread blocks is simply superb, whether negotiating sticky mud, wet stone slabs or polished café floors. Like most cyclists, I try to put a foot down as little as possible, but the odd stretch of walking is unavoidable. After more than six months of use, wear to the blocks is minimal. The front block has taken the brunt, but it’s easily replaceable. If you need more aggressive grip, two studs can be fitted as an option.

Adjustment is good, but not stellar. Perhaps it’s just me, but I find Sidi’s Techno-3 rotary dials fiddly, especially when wearing gloves in colder weather. They are every bit as adjustable as Boa’s dials, but the process of tightening and loosening them is more of a faff. It’s not impossible on the move, but it’s slow and rarely a joy.

Velcro-style hook and loop is what it is. In this case, the wide, wrap-over strap brings stability to the upper and offers a level of micro-adjustment and simplicity that Boa and the like can only dream of. Again, it takes time to adjust, but I value the support it offers and love the visual character it brings to the Aertis.

The insoles are fine, but it would be nice to have a variety of arch support inserts included at this price point.

Value and conclusions

The Aertis is a great all-rounder. It’s no great surprise that an XC shoe makes for a decent gravel shoe, but because it’s so similar in build and features to Sidi’s Prima it’s also a fabulous endurance/all-road/bikepacking shoe.

Like most pre-Millennium last shoes from Sidi, it takes no prisoners if the fit isn’t right. Ideally, I would have liked the toe box and mid-foot to be a little wider, and I have regular-shaped feet. If you’re wide-footed, you may struggle.

The Aertis, which is made in Romania, appears to be very well put together. My pair is now a bit grubby, but holding up well, with no real signs of wear other than a slightly roughed-up sole.

At £175/$239 they represent good, if not exceptional, value when you consider their versatility, features and build quality. That’s about the same price as a pair of Specialized Recon 2 shoes, and slightly more than the Terra Powerstrap X4 and Terra Atlas models from Fizik. They sit comfortably in the mid-range, provided you don’t have wide feet!

Specs

• Available in both men's and women's versions
• Sizes: M 36 – 50. W 36 – 43
• Weight (size 48): 415g per shoe
• Cleat standard: 2-bolt SPD
• Upper: Politex
• Sole: Nylon
• Stiffness rating: 6 out of 12 on Sidi's scale