Prolight SLX: with a name like that you can pretty much guess what Giro's top end road shoes are all about – lightness and a pro-level performance. At just 205g per shoe (size 42), the Prolight's are some of the lightest on the market thanks to a lack of mechanical closures, a smattering of titanium bling bits and an ultrathin Easton EC90SLX carbon sole.
At a glance, there doesn't seem to be much difference between these Prolights and the Factors we tested a little while ago. Look a little deeper, though, and you'll find all the little tweaks that shave off the extra 50g.
The road shoe market is a pretty busy place and with competition at this price point from the likes of Sidi and Shimano, Giro set about building a shoe from scratch. The first part of the process was to create the perfect last (the foot shape the shoe is built around). Sixteen versions were created before Giro were happy with the fit.
Once the shape of the last was sorted, it was time to start working on that all important sole. Luckily for Giro's designers, the carbon bods at Easton are part of the same parent company, so with the expertise in-house, work started on the Easton EC90SLX high modulus sole. Just 6.5mm thick, it brings your foot close to the action. All the hardware is titanium as opposed to the steel seen on the Factors. Along with the thinner, lighter sole, this results in a slight weight saving.
The uppers are made from Teijin microfiber: a sort of manmade leather. It's a one piece construction with an in-moulded heel cup minimising any irritation or rubbing from seams or joins. It's only 1.1mm thick but it looks to be pretty hardwearing and wipes clean. That's ideal if you go for the white ones. There are air holes on each panel for ventilation plus mesh sections to keep your tootsies cool in warm weather.
The biggest weight saving comes from the removal of the ratchet and buckle closure. It does look odd to see a £260 pair of shoes with just three Velcro straps holding them onto your foot, but it works. There is no loss of adjustment or security compared with a ratchet, it's just a bit more difficult to tweak the tension on the fly. The other reason for the lack of mechanical closure is down to Levi Leipheimer, who had a fair bit of input in the design. He didn't want to risk a broken ratchet after a crash in what could be a crucial part of a race.
The top two titanium strap buckles are offset to avoid pressure points on your instep. Having the buckles further over towards the outside of your foot does allow more of the upper to be pulled over the top, almost wrapping it around your foot.
Inside, the Easton sole is neutral, allowing for the use of the SuperNatural Fit Kit insole to custom fit them to any foot shape. Three varying arch profile inserts are included which Velcro to the base of the insole. The Prolights (like the Factors) allow the fitting of any orthotics that you already have set up in your current shoes.
Once on the bike, I found the fit spot on with the upper moulding to your foot shape after just a couple of rides. The stiffness from the sole is absorbed through the insole, and even when getting the power down there is enough shock absorption to keep things comfortable. The light weight really does make you feel like you aren't wearing any shoes at all (in a good way).
The sole is compatible with all cleats using the three bolt fixing system and there are measurement graphics to aid cleat change.
Overall, the Prolight SLX's are impressive with a good balance between comfort and stiffness. The finishing quality looks top notch as well. If you save them just for weekend jaunts into the country or racing, you should get plenty of seasons out of them.
With sizes ranging from 39-48 and half sizes from 39.5-46.5, most people will be able to get a good fit. The price is clearly high but the shoes, custom insoles and even a shoe bag all add together to make a decent package.
Lightweight shoes that are stiff and comfortable with a pro-level performance
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road.cc test report
Make and model: Giro Prolight SLX Cycling Shoes
Size tested: White - size 45
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
The Prolights are a pro-level shoe with light weight and performance to match,
Giro reckon,"The ultimate combination of power, weight and performance without compromise." Yep, that pretty much covers it
Tell us some more about the technical aspects of the product?
The Teijin material provides an instantly comfortable upper. It's very soft yet hardwearing.
Looks very good quality with no rough edges.
Very light and the power transfer is top notch.
I wouldn't wear these shoes every day. I'd save them for special events and Sunday best.
Some of the lightest shoes out there without compromising stiffness and power transfer.
Beautiful. That soft upper moulds to your foot as you put the miles in.
They're not cheap but they're worth every penny.
Tell us how the product performed overall when used for its designed purpose
Great: stiff, light and comfortable.
Tell us what you particularly liked about the product
The fit and the look.
Tell us what you particularly disliked about the product
I preferred having the ratchet system on the Factors to be able to tweak the fit on the fly.
Did you enjoy using the product? Yes
Would you consider buying the product? I'd personally go for the Factors
Would you recommend the product to a friend? Yes
About the tester
Age: 32 Height: 180cm Weight: 78kg
I usually ride: Genesis Flyer My best bike is: Ribble Gran Fondo
I've been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed
With 20 years of road cycling and over 150,000 miles in his legs it's safe to say Stu is happiest when on the bike whatever the weather. Since writing his first review for road.cc back in 2009 he has also had a career in engineering including 3D-CAD design and product development, so has a real passion for all of the latest technology coming through in the industry but is also a sucker for a classic steel frame, skinny tyres, rim brakes and a damn good paintjob.
His fascination with gravel bikes is getting out of control too!