Changing an innertube

Cyclescheme, 18.01.2012

Changing an innertube

With a few tools and a little practice, a puncture is a minor inconvenience rather than a catastrophe.

You will need

- An innertube of the correct size and valve type.

- A pump. Mini floor pumps like Topeak’s Morph range are the easiest to use.

- Two tyre levers. Pedro’s and Park are good, while the Var 425 is ideal for tight tyres.

                 

You may want

– 15mm spanner, for bikes with wheel nuts.

- Puncture kit, in case you puncture twice.

- Zip-ties

– Small penknife

- Compressed gas cartridges, to save time pumping.

 

1 Release the brake

To get even a semi-inflated tyre past a rim brake’s pads, you may need to undo the brake. Sidepull brakes have a little lever on the calliper that opens the brake further. With V-brakes, the J-shaped metal ‘noodle’ unhooks from the yoke. With cantilever brakes, the cable unhooks from one brake arm. If you’ve got disc brakes, you don’t have to do anything.
 


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2 Ready the rear wheel

Puncture in the back tyre? If your bike has a rear derailleur, click up the gears until the chain is on the smallest sprocket at the back. If it’s a singlespeed or hub-geared bike and the dropouts are open to the rear, you’ll need to slacken the wheel nuts, slide the wheel forward, then lift the chain off chainring and sprocket. You’ll also need to detach a hub gear’s cable near or at the hub.

 

3 Put the bike upside down

Not essential but easier if you’re on your own. The bike rests on the saddle and handlebar. You may need to remove bags and anything mounted on the bar.

 

4 Remove the wheel

Undo the quick release lever. For the front wheel, you’ll also need to partly unscrew the knurled nut on the opposite side, because modern fork dropouts have lips to stop the front wheel falling out accidentally. Lift the wheel out, noting which side the quick release lever was on so that you can put wheel back the same way. For the rear wheel, pull the derailleur back out of the way and lift the wheel up and out.

 

5 Lever off one tyre edge

Insert one tyre lever under the edge of the tyre (the bead) and lever it off the rim. Either hold this lever or slot the end behind a spoke while you insert the second tyre lever about 10cm away on the same side. Lever up the bead, then run the second lever around the rim, lifting off the tyre completely on one side only.

 

6 Remove innertube

Remove the valve cap and locking ring, if any, then remove the tube. Unless the source of the puncture is obvious, such as a huge thorn stuck in the tyre, inflate the tube (to at least the width of the tyre). Feed the tube past your ear, listening for escaping air. Can’t hear anything? Wet your lips and feed the tube past them to feel for escaping air.

 

7 Check the tyre

Now hold the tyre against the wheel, matching valve with valve hole. Unless you flipped the innertube horizontally, the hole in the tube – which you’ve just found – will line up with whatever caused it. Run your fingers carefully inside the tyre to see if the sharp object is still there. If so, remove it – a knife helps. If you don’t find anything, feel around the rest of the tyre just in case. But it may have fallen out.

 

8 Fit new tube

Pack away the punctured tube for fixing at home. Pump a little air into the new tube, enough to give it some shape. Fit the valve through the valve hole, then feed the rest of the tube into the tyre.

 

9 Refit tyre

Starting opposite the valve, to make fitting easier, tuck the tyre bead back into the rim with the thumbs of both hands. Work both hands around the tyre, in opposite directions, tucking in the bead as you go. You’ll fit most of the tyre like this. If the tyre keeps springing out of the rim – some puncture resistant tyres will - zip-tie it in place at eight o’clock and four o’clock, assuming the valve is at 12 o’clock.

 

10 Fit last section of tyre

At about five-to-one on our wheel-as-clock, the tyre will become tight, the bead running straight across between your thumbs. It’s tempting to reach for tyre levers at this point. Don’t: you’ll pinch the innertube and puncture it. First let the air out of the innertube so it won’t resist you. Then work around the already fitted section of tyre, pressing it down into the central well of the rim. The rim well is lower than its edge, so the wheel diameter is smaller there. Pushing the tyre into it will win you some slack so you can push more of the tight section over the rim. Repeat as necessary. Eventually you’ll be able to lever it on with your thumbs. If not, flip the wheel to face away from you and roll the tyre towards you using one or both hands.

 

11. Final checks

Check that the tube isn’t trapped under the bead at the valve by pressing the valve up into the valve hole. Pump up the tyre a little to give it some shape. Spin the wheel to ensure the tyre is mounted evenly on the rim. If not, you’ll need to push and pull the tyre side to side until it fits neatly. Then inflate the tyre until it’s firm. Refit valve cap etc.

 

12. Refit the wheel

Front wheel: You noted which side the quick release lever was on as you removed the wheel (see 4), so you’ll be able to fit it the same way round. Make sure the quick release lever is open. Fit the axle into the dropouts. Push down on the wheel to ensure it’s properly seated. Tighten the knurled nut on the other end of the quick release enough that the lever starts to snug tight when it’s about half way closed. Closing it fully should require firm pressure.

Rear wheel: Pull the derailleur back, align the smallest sprocket with the ‘top’ run of chain (i.e. nearest the ground, when the bike is upside down), and guide the axle into the dropouts. Push the wheel firmly into the dropouts, then do up the quick release securely.

Singlespeed or hub-gear rear wheel: Put the wheel into the dropouts, pushing it forward so you can refit the chain. Pull it back in the dropouts to tension the chain, check wheel alignment, then tighten the wheel nuts. Reconnect the gear cable, if any.

Just don’t forget to reconnect the brake you undid, then you’re ready to go. You can mend the punctured tube at home, at your leisure.
 


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