WE have all had that sinking feeling that follows a puncture. With the hiss of escaping air in our ears, Dorset Trails hooked up with mechanic, Jon Hayes, for the inside track on getting inside your tyres.

“There’s a few simple tricks to mending a puncture that make the process a whole lot easier, and once you’ve done them a couple of times, they become second nature,” says Jon.

So lets get started.

Step One - removing the wheel

Mountain bikes have a wide range of gears, up to 30 on the cream of the crop, but commonly 24 on even the most humble machines. If you’re releasing the rear wheel, be sure to first shift the chain on to the smallest of the rear sprockets. This will make it easier to engage and disengage the wheel.

Most modern mountain bikes will have a quick release lever, which, as the name suggests, releases the wheel quickly. A detail worth remembering - it’s a lever not a bolt, so go easy when undoing and tightening it. Older bikes will have wheel nuts, usually 15mm.

A final note on punctures in the rear tyre. When releasing the wheel, gently push down on the derailleur (the gear mechanism) before easing the wheel forward. Simples.

Step Two - removing the tyre

The trusty tyre lever is your aid here.

Insert it between the tyre bead and the wheel at the furthest point from the valve and prise the tyre over the rim. If the tyre bead is tight, use two levers, leaving one in place and “leap frogging” with the other until the entire circumference of the tyre has been prised away from the wheel.

Put your hand inside the tyre, ease the valve from the hole in the wheel rim and pull out the tube.

Step Three - checking the tyre

Carefully check the inside surface of the tyre. Remember Jon’s warning: whatever has cut through the thick rubber of your tyre while certainly cut your fingers, so feel carefully for any foreign objects which will only puncture you’re replacement/repaired tube.

Step four - fitting the replacement tube

Partially inflating your new tube will make it far easier to fit. Only a few psi are needed at this stage; just enough to give the tube some shape. When refitting the tyre, check the direction indicator on the sidewall. This step isn’t essential, but you can assume that if the tyre manufacture has bothered to test an optimum rolling direction, it’s worth using.

Put the valve through the hole in the wheel rim and gently feed the tube under the tyre cover.

Once the entire tube is in place, ease the tyre bead back over the wheel rim. The final section will be tight and may need assistance from your friend the tyre lever.

Be careful here to avoid the dreaded “pinch flat” by trapping the tube between the tyre bead and the rim. To make sure the tyre is properly seated, squeeze it around the entire circumference of the wheel.

Step five – fully inflate the tyre

Reconnect your pump to the valve and inflate the tyre. Jon’s recommendation for riders of average weight on general rides is to use between 30 and 40psi. He highlights the common mistake of over inflating the tyres. Rock hard tyres are more vulnerable to puncture, and an over-inflated front tyre will slide away from you on really loose surfaces. A slight “give” in the tyre spreads its contact patch and gives more grip. Less is more.

Step six - relocate the wheel

Prepare to reap the dividend from selecting the smallest rear sprocket when you removed the rear wheel. It should now be far easier to engage the sprocket with the chain and to guide the axle into the frame. Again, if you’re changing a rear wheel, gently press down the derailleur as you guide the wheel back into the frame.

Grip the non-levered end of the quick release mechanism, and tighten the skewer slightly by turning the open lever. When you have some tension, close the lever firmly, but gently. If the lever won’t close, the skewer has been over- tightened, so back it off a couple of turns and try again.