The Sole Decision– Should I Go with a Carbon, Plastic, or Composite Sole Cycling Shoe?
Ok, bad puns aside, an important question you should ask yourself before buying new cycling shoes is what
type of sole material is suitable for my riding style, and should I go with a carbon sole or not. It can be
confusing wading through the marketing hype to decide on entry level plastic, composite, or a higher end carbon
sole bike shoe. Full carbon is really sexy, but is the bling worth the extra cash that may be better used to
pay the rent?
Right off the bat, I would say don't short yourself. After a helmet, shoes are probably the most important
accessory you will buy after you have forked over those thousands on a sweet new ride. They are your direct power
connection between your feet and pedals, and you don't want to be losing energy to sub standard flexy shoes.
Stiffness Vs Weight
Aside from cost, the main differences between carbon and plastic/nylon soles is stiffness and
weight. Plastic soled shoes are mass produced by injection molding, and the resulting material is heavier than
carbon. This process is simpler than laying up carbon and means plastic soled shoes can be sold cheaply
in large production runs.
The majority of all cycling shoes at the high end of the model ranges are now created from carbon fiber or
a combination of carbon and composite. Carbon offers a very stiff, light platform translating to better pedaling
efficiency and control. Just like wheels, pedals and shoes are rotating components. The lighter you can make them
while maintaining stiffness, component strength and pedaling efficiency the better.
Bicycle manufacturers improve the ride characteristics and comfort by building compliance (flex) into their
carbon frames by varying the tube thickness, diameter and weave in different parts of the frame. If you have
ridden several carbon bikes you will notice that they all have different ride characteristics depending on the
Back in shoe land however the jury is still undecided on whether to go with as stiff as you can
carbon or build in a little compliance. Manufacturers such as Sidi claim a completely stiff sole can lead to
hot spots and poor foot circulation on longer rides. In their Genius 5 and 6 line, they have
built a slight amount of flex into the toe area by varying the carbon thickness and structural design.
High End Carbon Cycling Shoes
Carbon sole cycling shoes tend to last longer to original specification. This would mainly apply to stiffness,
but higher end models also tend to have better construction and materials. Plastic soled shoes on the other hand
will weaken over time as the continual flexing of the sole gradually weakens the platform. Changes in
temperature will also affect a plastic sole with hotter temperatures creating more flex. This flex reduces your
Mid Range Composite Cycling Shoes
Mid range cycling shoes can be a combination of carbon fiber and plastic. The process of injection molding
carbon and nylon creates a mid to higher range product that is much less susceptible to the weaknesses of plastic
soles. This can be a great solution if you don't have another $100-$200 to fork over for 100% carbon. However over
time these soles will still lose their rigidity and you may end up having to buy a new pair before the uppers need
Mid Range to Low End Plastic Cycling Shoes
On the lower end of the scale you will find cycling shoes that are full nylon or a fiberglass/nylon
composite. Some soles are also made from fiberglass/reinforced carbon composite. Generally even
though the soles may last on some of these shoes for a reasonable time the uppers tend to be of lower quality and
prone to premature failure.
Carbon soles are making their way through the ranks of mtb shoes as well and although not as comfortable
as plastic soles to walk in due to higher rigidity they offer better power transfer. For me, the
tradeoff is worth it, and in any event I don't plan to do much walking.
If you ride more than an hour and a half at a time you will appreciate the benefits carbon cycling
shoes give. With the high quality of upper level carbon soled shoes, your investment should give you a
fine return over the long run. However, if you are hard on equipment, you can probably get several pairs of mid
to low end shoes for the price of one high end pair. This enables you to keep your feet in a relatively
new pair of shoes for the same investment at the expense of sacrificing some performance.
It is my humble opinion that carbon will be a mainstay in a majority of shoe soles
before long. As happened with bicycle frames, the technology will filter down to more and more
Personally, I ride full carbon sole cycling shoes on my road bike. They are super light, stiff, and when I
am climbing or out of the saddle sprinting in a crit I appreciate the full power transfer I am getting between foot
and pedal. I also like the fact that I can use a cleat with a smaller contact area if I desire and not feel it
poking through the bottom of the shoe. I am almost due for a new pair and yes they will be sexy full carbon shoes!
Once you ride with carbon shoes my bet is you will never go back.
Check out a range of carbon cycling shoes here.
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