Along with shoes, Giro saw the need for
better insoles. They so liked the results of their insole design work
that they're selling them as an after-market accessory, the SuperNatural Fit Kit.
Their goals were to make their insoles more comfortable for a wide
range of foot types, and that they'd offer enough adjustability to
perhaps negate the need for investing in custom insoles.
One of the few benefits of the wafer-thin insole that many shoe companies supply with shoes is that it is
wafer thin. No bulk in what is an extremely close-fitting shoe is most
often a good thing. This keeps the ball of the foot very close to the
sole and in turn the pedal spindle, minimizing stack height, and it
keeps the heel very low in the heel cup, maximizing the cup's ability to
hold the heel down. Giro started with these two benefits and added one
of the benefits of custom insoles; arch support. Arch support, is
critical for cycling comfort. When the leg pushes down on the foot, the
arch can flex, which can lead to shoe movement, which can lead to
alignment issues, to the foot moving in the shoe, to developing hot
Another benefit of custom and semi-custom insoles is a
"metatarsal button" that provides greater mid-foot comfort. Giro has
included a subtle button as they've found wide variation in individual
rider's ability to find such a feature comfortable.
The base of
the insole is a thin layer of EVA foam. It's thick enough that normal
use of the insoles will help to customize, or tune, or crush some of the
EVA so that you'll see divots in the foam after a few rides. This will
increase the surface area of contact points, which should increase
comfort, but the EVA is secondary to the three arch supports that come
with each insole.
There is a small, medium, and large arch. They
can be easily and quickly swapped in and out. The small maintains the
contour of the insole itself. The medium adds 3mm to the arch compared
to the small. The large adds another 3mm beyond the medium. These are
easy to use. First, in either bare or thinly-socked feet, place the
support under your foot. Try different sizes until you find one that
seems snug against your foot. You want it close because you don't want
your arch acting like a leaf-spring each pedal stroke. Figure out the
size. Ride. Adjust if necessary.
The insoles are covered with
X-Static fabric. The name is familiar because you've already seen Giro
and others use it in helmet pads. It's a silver, the mineral, fiber that
is bonded to a polyester fabric to make the fabric anti-microbial,
You'll see that each size of the Giro SuperNatural Fit Kit
fits a number of size shoes. These are "trim to fit" insoles and
there's a cutting guide underneath each insole, but your best bet is to
either compare it to your stock insole or shove it inside your shoe
before commencing on any alterations.