HANOVER (dpa) – Most people only give them a thought when they go flat but tyres are among the most important components of any bicycle.
Riders who pay more attention to their tyres though are likely to get from A to B less strenuously and with a little foresight journeys can be altogether more pleasant.
The choice of tyres is so important that it’s something buyers should think about when buying a new mount. “They are tyres for the most diverse applications and tastes,” said Karsten Klama of Germany’s ADFC national bicycle club in Bremen. It all depends on whether the bike will be used in the city, on long trips or for sporting activity.
For city use cyclists can dispense with treaded tyres altogether even in rainy conditions. Bald tyres or “slicks” enable the rider to transfer maximum leg power to the road since only a negligible amount of energy is lost by the tyre carcass flexing.
Such tyres provide enough adhesion for normal usage although they do have the disadvantage of picking up more grit, glass and dirt from the road which can stick to the tyre. Tyres with more profile have a self-cleansing effect, flinging off small stones and other road debris as they revolve.
“Knobby” or heavy tread tyre used by mountain bikers for offroad excursions, have few advantages on urban streets. Apart from the additional friction or drag which can slow the rider, they make a noisy “hum” on the asphalt which can be irritating. “You can invariably hear a mountain bike coming,” said Siegfried Neuberger, spokesman of the Federation of Two-Wheeler industries.
So-called “semi-slicks” are a good compromise. “These are very smooth in the centre of the contact area, with tread at the edges,” explained Wolf vorm Walde, product manager at Continental in Hanover. Riders can make brisk progress on metalled roads but still have enough grip for farm tracks or unmade paths. Bicycle magazines often carry test reports on tyre types, comparing the rolling resistance and susceptibility to puncture of a wide range on offer.
Apart from tread considerations cyclists should give some thought to the amount of air in their tyres. “Air pressure really is the most important thing,” said Karsten Klama of the ADFC. Too little air means the rider has to work harder to overcome rolling resistance and it can cause damage to the tyre. For urban riding Klama recommends between 4.5 and 5 bars of pressure although for extra comfort between 3 and 3.5 bars will suffice.
A tyre running with insufficient pressure punctures more easily if the rider bumps up over a kerbstone or can lead to so-called “snakebites”, punctures caused when the tube presses onto the spoke eyelet wells. It’s worth checking air pressure regularly although the maximum permitted pressures are hard to achieve with a simple hand pump. Cyclists using car-type valves on their tyres can always check their pressures at a local petrol station.
Bicycle tyres are still being developed and innovations include insert belts made of kevlar fibre or nylon in a bid to reduce punctures. Tyres with reflective sidewalls may soon make plastic reflectors redundant. Continental says these are already a legal requirement in Denmark and Sweden, both safety-conscious countries with a high proportion of cyclists. Meanwhile tubeless tyres have failed to catch on.
Swapping to new tyres can be expensive and new ones from a reputable manufacturer cannot be had for under 20 dollars for a set of two. Wear is inevitable and Continental reckons that tyres are good for around 5,000 kilometres before replacement is necessary.
“We have had reports of tyres lasting up to 15,000 km,” said vorm Walde. According to the tyre expert, even people who only use their bike occasionally will need to buy fresh tyres every four years. After that period the rubber compound used is past its best and is liable to splits and cracks.
