|
YouTube Video of changing a flat
Introduction
Types of punctures and causes
How To Fix A Flat
- Remove the wheel
- Remove the tire and tube
- Inspect the tube
- Inspect the tire
- Patch the tube
- Reinstall the tube
- Reinstall the wheel
Introduction
Don't let a flat tire ruin your ride - take control by learning how
to fix a flat properly. You can also find instructions with helpful
photos on the Toronto Bicycle Users Group (BUG) website at
www.toronto.ca/bug/tire_repair.htm. Practice in the comfort of you own
home by deflating a tire and going through the motions - that way you
won't be as stressed out if (and when) you have to do it on the road!
You will need:
- tire levers (use ones made of plastic, not metal)
- patch kit or glueless patches (scabs)
- tire pump
- if you have non-quick release wheels, you'll need a wrench
A good patch kit should contain:
- Several patches of various shapes and sizes
- Tube of rubber cement (check that the glue is still liquid - once tubes are opened they dry up quickly)
- Sandpaper for preparing the tube
- Chalk for marking punctures (optional)
- 1" x 2" homemade patches of denim or canvas to cover tire cuts (optional)
Back to top.
Types of punctures and causes
Small pierce or hole: possibly a piece of glass, a staple, or
other small, sharp object. If you hole is on the inside of the tube, it
may be caused by a spoke protruding through the rim tape inside of the
rim
"Snake bite" or rim pinch: two parallel slits, caused by
under-inflated tires or an impact on the rim (usually a pothole); the
tire has compressed and squeezed the tube against the rim.
Blowout: a large hole like a starburst; usually caused by riding over a sharp object
Tear at valve stem: these cannot be repaired; caused by an improperly inserted valve - make sure the valve protrudes at a 90° angle to the rim
Back to top.
How To Fix A Flat
1. Remove the wheel
These instructions are for the rear wheel but you can use them for
the front wheel too - just ignore the references to the chain and
derailleur.
- Shift the chain to the smallest cog
- If you have them, loosen the quick release on the brakes.
- Open the quick release on the wheel hub, pull the derailleur back
to make room for the cogs to clear the chain, and remove the wheel by
lifting it out of the dropouts
- If you don't have quick release, you will need to loosen and remove both the wheel nuts
- Lay your bicycle on the ground with the derailleur side up, to
avoid getting dirt in the free wheel and chain. Do not stand the bike
on the derailleur.
Back to top.
2. Remove the tire & tube
- Fully deflate your inner tube by pressing down on the valve; this will make it easier to remove
- Insert a tire lever under the side of the tire (the bead), on the
opposite side of the valve. Most tire levers have a hook on the end
that can be attached to a spoke to keep it in place
- Insert the other lever about 5-10 cm away
- Pry the bead up and over the rim by working the levers both at once
- Slide one lever around the edge of the rim to remove one side of the tire off of the rim
- Reach inside the tire and pull out the tube all around, ending at the valve
- Carefully pull the valve stem out of the rim hole (if there is a lock nut, remove it first)
Back to top.
3. Inspect the tube
- Take your pump and put a few strokes of air into the tube.
- Find the hole by rotating the tube while holding it close to your
ear and listening for air hissing from the puncture. You can also try
holding the tube close to your lips so you will feel escaping air on
the sensitive skin above your lip. Or immerse the inflated tube into
water and watch for bubbles.
- If the hole is tiny you may want to mark it with a piece of chalk or crayon
- Note where the hole is in relation to the valve. Be sure to inspect that area on the tire with extra care
Back to top.
4. Inspect the tire
- Inspect the tire inside and out for the offending object,
including sidewall. Run your fingers inside the tire, being careful not
to cut yourself
- Check inside any tears for bits of glass
- Inspect the rim tape inside the rim to make sure there are no holes where spokes are may be poking through
- If there is a large tear in the tire rubber or sidewall, you may
need a "boot" - something to wrap around the inside of the tire to
prevent the tube from pushing through the tear. A patch of denim or an
energy bar wrapper works well for this purpose.
Back to top.
5. Patch the tube
- Patching the tube is easy and creates less waste. But if you
really want to replace the tube with a new one, skip to the section on
Reinstalling the tube.
- Take the sandpaper from your patch kit and rough up the surface
of the tube around the hole. The tube surface under the patch must be
dry and clean
- Spread a layer of glue around the hole; the area of glue needs to be larger than the patch
- Let the glue dry until it is tacky and has lost its gloss (usually less than a minute)
- Place the patch over the hole and use your fingers to press the patch in place and smooth out any air bubbles.
- Test the seal by putting a few strokes of air into the tube
(Sometimes you will find a second puncture at this point that needs to
be patched)
Back to top.
6. Reinstall the tube
- Put just enough air in the tube so that it holds its shape
- Put the tube valve through the rim valve hole
- Tuck the tube inside the tire, avoiding kinks, bends and twists.
- Deflate the tube again
- Work tire bead back onto rim, starting at the valve area and
working around, using your thumbs to push the bead over the edge of the
rim.
- Getting the last bit of tire onto the rim may be very difficult;
use a vigorous twisting motion of the wrists to force it on. Use tire
levers only you really have to - be very careful not to pinch the tube,
causing a puncture
- Push and pull the valve to make sure it is 90° to the rim; a crooked valve can lead to a flat tire later
- Check around each side of the rim by rolling the tire back to
make sure that the tube is completely seated within the tire - if any
of the tube protrudes it could lead to a pinch flat later.
- Pump 20-30 lbs of pressure into the tire and check that the valve is still straight and that the tire is seating properly
- Inflate to full pressure; it may be necessary to press downward above the valve in order to engage the pump head
- Reinstall and tighten the locking nut on the valve, if any
Back to top.
7. Reinstall the wheel
- Position chain over smallest cog and pull the axle back into dropouts
- Center the rim between the chainstays and firmly tighten the quick-release (or the nuts)
- Close the quick-release on the brake callipers
- Spin the wheel and check that the wheel is secure and centred
between the brake pads; if not, loosen and try again. Now go catch up
to your friends!
Back to top.
|
Participants 
