Mountain Biking and Mountain Bikes for Africa









MTB Tyre Puncture Prevention

Punctures and flats have been a part of mountain biking and cycling from the very beginning. Fixing flat tyres and punctures is not difficult but can be an irritation and a waste of valuable riding time and worst case can end your ride in a long walk home.

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.


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