Castelli's new Aero Speed gloves take the whole marginal gains thing right to its limit but if you've ever spent any time with a time-triallist you'll know just how fastidious they are about kit.
Your hands are the first part of your body to push through the air when on your aerobars, so by smoothing the leading surface of your fingers Castelli claims a saving of 8W (normalised power) at 40km/h over a standard pair of mitts.
They achieve this by having the middle, ring and little finger as one section while leaving the index finger and thumb separate for shifting and braking duties. You tend not to move your hands about too much in a time trial so any loss of dexterity isn't an issue, though if you wear the white ones it can look like your hands are bandaged up boxer style.
The Lycra is very thin and stretchy so stays taught across your fingers whatever position your hands are in while the long slim cuff blends into your arm, especially when used with Bodypaint Speedsuit 3.0 these gloves are designed to partner.
That thinness in the material does mean they are a little fragile though so a bit of care is needed when putting them on or taking off so as not to pull the stitching. It's no worse than any other top end race day kit though.
Padding is pretty much non-existent but as you very rarely have your bodyweight on your hands as you do in a normal road position it makes little difference. The material does enough to take the road buzz out but if you're after comfort you probably aren't going to be riding a time trial in the first place.
Grip is provided by two sections of silicone at the base of the palm with one side running up the underside of the thumb. It's positioned exactly where it's needed for both the aerobars and the base bar for braking and hard cornering.
They grip in the wet on bars with no tape as well.
They come in three options colour coded to match the speedsuits: white/red, black and fluoro yellow/black. The last one actually offers a bit of hi-viz in a cool way. Sizing is based on the width of your palm with the XS for less than 17cm and the XXL going up to 27cm plus.
Overall the Aero Speed Gloves are designed for specialist use and do that job well. The power saving claims made by Castelli are impossible for us to replicate on the open road but even if only a quarter of the claimed 8W is real, a gain is still a gain.
The fit is excellent and they are very comfortable indeed especially once you are on the bike and don't need to move your fingers around much. The quality is typical Castelli, well made and attention to the smallest details like the pull tab for putting them on or the grip positioning. Priced at £35 they aren't extortionate either when compared to a lot of other mitts on the market.
Specialist mitts for the fast guys and gals that offer not just a performance gain but also a psychological one.
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Make and model: Castelli Aero Speed glove
Size tested: L
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 Aero Speed gloves are designed for time trialing and triathlons where aerodynamics is more of a concern than comfort or usability. Castelli say that fingers are a disaster when they hit the wind so by smoothing the surface you save power. Sound enough logic.
Tell us some more about the technical aspects of the product?
*Covered fingers for aerodynamic advantage
*Precurved palm design
*Silicone grip on palm
*White/red, Black, Flouro yellow/Black
*Silicone grip on palm
Can be a bit fragile but they are designed for race day not day in day out abuse.
Heavily padded palms can be uncomfortable wrapped around the narrow 22mm diameter of aero extensions; these don't ruck up or crease at all.
Tell us how the product performed overall when used for its designed purpose
We can't back up Castelli's performance claims but on the bike in the middle of a race you don't realise you're wearing them.
Tell us what you particularly liked about the product
The fit and comfort
Tell us what you particularly disliked about the product
Can be tricky to get off especially when you've just collapsed at the end of a race.
Did you enjoy using the product? Yes.
Would you consider buying the product? Yes.
Would you recommend the product to a friend? Yes.
Age: 35 Height: 180cm Weight: 76kg
I usually ride: Whatever needs testing or Genesis Flyer, fixed of course! My best bike is: Kinesis T2 with full Centaur Red
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!