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Sherborne Times October 2018

Scottish inventor John Boyd Dunlop made the first practical pneumatic tyre in 1887 to prevent his son getting headaches riding on rough roads. Since then we have enjoyed greater comfort but at the risk of the dreaded puncture. Early tyres had heavy inner tubes and a simple valve which relied on a piece of rubber tube prone to perishing. Pumps were basic devices and the way to check you had enough air pressure was to press the tyre with your thumb.
Since Mr Dunlop’s invention, manufacturers have tried many wheel sizes, both metric and imperial so the range of tyre sizes is huge and also the applications and tread patterns have increased, which means we must carry stock of hundreds of tyres and tubes to be able to provide a replacement on demand.
Modern tyres offer so many choices even including colour. As well as the size, manufacturers provide ratings for puncture resistance, grip, durability and rolling resistance which a rider must select from. On high performance bikes, weight is also a factor and aesthetics is becoming more important for some.
We have been experimenting with tubeless tyres for road bikes, as off road riders give glowing reports of their performance. Results are promising on mine and Darren’s wheels. Key points we found are: high performance, light tyres are not suited for heavier riders on our poor roads, so best to choose a more durable tyre; sealants are not all equal; the thinnest tyres road are not suited to tubeless use; achieving the initial seal either happens first time or takes ages and careful preparation can save frustration.

Puncture Protection
Modern road bikes have lighter, narrower tyres and tubes with reliable valves to hold higher pressure, so old techniques for inflation and testing are not suitable. It is not possible to stop punctures totally, but you can reduce the likelihood significantly. There are two types of puncture, penetration (caused by a sharp object like thorns) and pinch (caused by hitting a bump when a tyre is under inflated and identifiable by 2 small adjacent slits which give it the moniker of snakebite puncture). My advice about avoiding punctures is:

  • Maintain correct tyre pressures. The minimum pressure will be embossed on the tyre wall, e.g. “min 50 – max 85 psi”on a hybrid. A tyre at 30psi (which feels like a lot of pumping when using a basic plastic pump) will feel hard if squeezed with your thumb, but the recommended range of pressures on a narrow road tyre is likely to be from 80 to 120psi, so the thumb test is not sufficient. A good pump and a gauge is easier and accurate.
    Fit good tyres with a puncture protection barrier – lightweight Kevlar reinforcement is a popular choice. Do not leave the tyres until they are wearing through the rubber; during routine inspection look for cuts, splits or holes, these can indicate the tyre is worn out or perished.
  • Good tubes – better tubes have more butyl in their composition which slows the rate that air molecules escape, so require less frequent inflation. An old tube with patches on is likely to leak, so replace it and keep it as a reserve.
  • Inspection and cleaning – wiping off tyres before and after rides allows you to spot bits of glass or grit which may lurk and worry away at the tyre while riding until they penetrate the inner tube.
  • Rim condition – steel rims may rust internally and cause punctures from within the wheel. There is also a rim tape to protect the tube from the spoke heads, these can deteriorate so check them occasionally. Rim tapes must be in good condition to perform their job of protecting the inner tube from the spokes.
  • Avoid debris and holes– there is more debris on roads during and after rain which washes stuff onto the roads, objects stick to the wet tyre and have more opportunity to penetrate. Don’t ride in the gutter or too close to the kerb as debris accumulates there. Look ahead to help avoid stones and pot holes.
  • Sealant – Cleverly formulated products added to the tube which are effective at sealing punctures, a little air may leak out before the sealant takes effect so the tyre may need a top up of air. We use the latest generation of sealant which does not contain latex and lasts longer.
  • Solid tyres which behave in a similar manner to a pneumatic tyre are available from Tannus as the ultimate puncture protection, but they are expensive.

Plan for the Worst
Punctures happen at the most inconvenient or unpleasant times, so be prepared and it might act as your anti puncture charm. Carry a repair kit of at least one inner tube, tyre levers, puncture kit and a means of inflation. If you are using tubeless tyres carry a tubeless repair kit. Try out your pump or CO2 inflator to learn how they work and practice replacement of an inner tube at home so you know what to expect.

Recovery service – carry a £10 note to call a taxi if you are stuck, the new notes are also useful as an emergency repair stuffed in the tyre when the tyre is badly cut. Carry a mobile phone to phone for help if you are stuck miles from home. Regular cyclists might consider Lexham’s recovery service, a year’s cover for £15 is cheaper than you would expect.