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Puncture prevention is
better than cure so the best is really to look where you
ride. This may seem obvious but don’t under estimate the
value of being conscious and cautious about where your
tyres roll. The faster and harder you ride the less time
you have to react and choose a clean line and the
greater your chance for cut tyres or punctures. So
cautious riding can reduce the risk of punctures
significantly by riding at a pace that allows you to
comfortably see what is ahead on the trail and take
evasive action or the best line to avoid any potential
tyre damage. But luckily mountain bikers have many
options available to prevent a blowout or flat wheel
from ending the ride. The main choices are tubeless
tyres with sealant, tubes with sealant, tyre liners and
thorn resistant tubes and sometimes a combination of
many of these methods.
Types of Punctures
There are three main types of punctures that can cause a
flat in mountain biking. The first is when a sharp
object like a thorn or nail penetrates the tyre making a
small hole, sometimes the thorn acts a plug for a while
and air loss is minimal but over time it wiggles loose
and the wheels goes flat. The second is when the tyre is
cut by a rock or piece of glass. The cut can either be
in the main tread area or on the side wall, either way
it’s a big deal and usually ends up as a blowout with
the wheel going flat quickly. The third type of puncture
is a pinch flat or also called “snake-bite”. This
happens on tubed tyres when the wheel hits a hard object
forcing the tube to be squashed against the rim
resulting in two little holes in the tubes looking like
a snake bite.
South Africa has some of
the harshest terrain in the world when it comes to
mountain bike punctures and wear and tear on tyres. The
Cape Epic has proved this, where the worlds best riders
have been caught out time and again despite having
access to the best equipment. The combination of our
rugged trails that have different types of sharp loose
rocks and a range of thorns from potent little devil
thorns to the long acacia thorns, make our riding
conditions quite extreme.
The trade off with
puncture protection comes down to weight vs protection
and then the effect on handling. If weight was no
problem then you could literally be bullet proof but
your wheel will weigh a ton and would not offer the best
handling characteristics. So what are the options
available out there?
Tubeless tyres with
sealant
Tubeless tyres with sealant are very simple and usually
consist of a tubeless tyre mounted on a tubeless rim
with valve and 50-100ml of tubeless tyre sealant inside.
This setup can also be achieved using a tubless
conversion kit where a normal rim is converted to a
tubeless tyre and rim setup. Tubeless tyres have proven
themselves to be the best compromise between puncture
protection and weight wile offering the best possible
grip and handling from the tyres. The sealant used in
the tubeless tyre is extremely effective and forms a
quick and effective plug as soon as a puncture occurs in
the tyre. If for some reason the sealant runs out or
there is a cut in the tyre too big for the sealant to
seal then you just need to put in a normal tube and you
are back on the trail again.
Tubeless tyres with
sealant have become the standard for the most effective
light weight puncture protection with no compromise in
tyre traction and handling. The downside of tubeless is
that the tyres and conversion can be costly and
complicated and messy to setup initially.
Tyre sealants in tubes
Before tubeless tyres came along this used to be the
next best way to prevent punctures by using a normal
tubed tyre and putting sealant into the tube via the
valve. There are many tyre sealants available for this
purpose but it turns out that the tubeless sealant can
also be used in tubes very effectively to deal with
punctures. The tubeless tyre sealant is usually quite
thin which allows it to be injected using a syringe or
applicator bottle. The sealant is injected into both
shraeder and preseta type tubes by removing the valve
cores. This tubeless sealant has also been used very
effectively in road tyres which are very susceptible to
punctures
The other more
traditional tyre sealants used in tubes have been
available for a long time with all sorts of names along
the lines of slime and sludge. These sealants come in a
bottle with an application tube that allow the tyre
sealant to be squeezed into the tube through the valve
by removing the inner valve core. The sealant is usually
a fairly thick liquid containing some sort of fibres
that assist with sealing holes. This means that most of
these types of sealants can only be put into tubes with
shraeder vlaves where the valve hole is big enough.
Slime tubes that have the sealant pre-filled into the
tube can be purchased from a variety of manufacturers
and are ready for use as is.
Tyre sealant in tubes is
probably the most cost effective route to go for
puncture prevention. However it still requires a tube
and the problem of pinch flats still exists.
Tyre liners
Tyre liners are strips of a very tough plastic that is
inserted on the inside of the tyre and sits between the
tyre and the tube. This can provide a vary effective
barrier to thorns and other puncture objects especially
if the are quire small and weak. It works for most
thorns, but very long or very hard thorns can still
penetrate all the way through. Tyre liners can be used
in conjunction with tubes with sealant to provide for a
very effective barrier with the ability to re-seal the
puncture hole.
This is a robust and cost
effective system. However weight and handling will be
compromised by using the tyre liners as they affect the
rolling and cornering properties of the tyre.
Thorn resistant tubes
Thorn resistant tubes are extra thick tubes with a wall
thickness of almost a millimetre. These tubes can be
used as is for an effective resistance to normal medium
to smaller thorns, but the big guys will still get
through. For a really effective solution tyre sealant
can be added to the tubes and they can be used in
conjunction with tyre liners. This will provide an
almost bullet prove solution for preventing punctures.
The thicker thorn tubes
can provide very good protection and even resist pinch
flats. However they are much heavier and more bulky than
standard tubes and do cost a bit more.
Tyre choice
Tyre choice can also play a large role in puncture
prevention. Many manufacturers offer puncture resistant
tyres that use Kevlar and other types of linings. This
is especially important for the sidewalls of the tyres
which is were most of the problem cuts occur. Although
these tyres are not puncture proof themselves that can
definitely improve or detract from a good solution.
Often the lightest tyres
are the thinnest and offer the least protection. The
heavier thicker tyres are more robust and offer the
added barrier to punctures. Identifying the right tyre
for the right type of trail conditions and riding style
will influence the ultimate choice. |
