What causes flats?  There are different bike designs made for special purpose, off road terrain competition, road pursuit racing and general purpose urban commuter designs that suits cyclists  personal needs. This includes tires.

The majority of flats is in the urban and city streets where tires pick up what ever road debris unlucky enough to pick up, such as slivers of motor vehicle glass littering the road, tax, hair wire or a stone imbedded in the tire. The most problematic is a persistent slow leak caused by pumped up to high near maximum tire pressure for the inner tube.

Tire pressures are found on the tire wall. Particularly hybrid bikes are built as a cross between off road competition and commuter asphalt. They tend to have tight fitting tires. Any tight fitting tire gives good asphalt road rolling resistance despite near minimum tire pressure.

Any tire a struggle to get off and on pumped to near maximum pressure, is an expansion of the inner tube compressed by the tight tire compressing to tight for the inner tube. The strain can develop complex slow leak problems. Even new inner tubes soon begin the habit of developing pin holes. Recommended for tires fitted to hybrid bike rims any any other tight fitting tire is near minimum tire pressure ideal for hiking tracks at the same time just as smooth on highway asphalt or city and urban streets.

Other causes unaware of an arrow on the tire wall. If an arrow rotates contrary to the drive direction ( going backwards to the peddling direction ) has a drastic effect on the tire transferred to inner tube. This too can cause pin hole problems.

Another cause the next time you have the tire off ( or any bicycle rim ) observing the inside edge of the rim. Most of us are unaware there is either a hooked or flat on the edge to bicycle rims. Correspondingly there should be a matching hook or flat design in the tire rim of the tire too.

If you assemble a hooked tire on a flat edged rim the tire doesn't sit properly. There will be tire damage issues transferred to the inner tube too. So too, a flat edge tire assembled on a hooked rim. Hooked or flat rims need corresponding hooked or flat rim edge tires.

Sudden and immediate flats is a sign of just picked debris. When you experience an examine the circumference of the tire the picked up debris is often spotted almost immediately before the wheel is even removed.

They are easy to find when you turn you bike upside down resting on the seat and handle bars turning the wheel round you can remove the offending object before you remove the wheel. If not removed, every time you inflate the picked up debris punctures another hole in the inner tube.

Punctures and slow leaks can be caused by budget repair kits, often a source of a patch repair failure. These puncture repairs can leak due to hurried jobs.

It starts with pealing away the packing material, a potential of getting greasy finger prints on the sticky side. The sealing side potentially attracts dirt particles the cement won't stick to. Damp and wet conditions can also effect proper procuring properties.

Reasonably priced patchy kits covers our bases in quality of both the cement ( or glue if you like ) and patches. Budget kits are not as good. Any cement carried round in bags during wet weather conditions often gets liquefied. Weather proof or even marine water proof bags prevents the cement being contaminated with moisture riding in wet weather conditions.

There are times when there is no evidence of a puncture. Pin holes are notorious to find which is the concentration of this post. The same procedures apply sticking a patch on any hole applies.

When there is no evidence of a puncture turn you attention to locating a pin hole. No hole can hide from an under water test. This of course requires a basin or bath tub of water. First pump up the inner tube.

If you are lucky enough at a petrol station you can use the free air station to do you repairs but if on the side of the road you can only make do with your hand pump you've got will have to do.

If there is no accesses to water, the only option is to pump the inner tube when out of the tire by hand with your hand pump as full as you can. Pin holes tend to keep the tube deflated as fast as you put air in.

Pin holes are so notorious to find it takes lengthy pumping to eventually feel a column of air locating the hole. If still frustrated if you have assess to water will help find it.

If you have accesses to same sort of water troth like a sink or bath immersing the inner tube eventually you will come across a bubbling column of air reveling pin hole. They are very tricky things.

If the only tube you have ( if at lest, for now ) there is a lot of trouble to find any pin hole. They are so tiny as soon as you you remove the tube out of the water you will loose site of the hole. It may take several attempts at re-immersing to keep track of it every time you dry the concerned area. You can only do the best you can. Once you have site of the tiny pin prick, with ball point pen circle it before you loose site of it again.

If there are previous patches you would have found one leaking It is important to wait for several seconds under water for any sign of a single bubble struggling to come out from under the patch or scan closely bubble fluff found the edge. At this point we end up asking ourselves if it now worth it. Bubbles resting on the surface of the tube is a dead give away the tube is leaking like a sieve from somewhere.

If desperate we  are can turn their attention to consider if it's the valve. Nine times out ten often proves OK. So keep expanding the inner tube feeling the circumference for a column of gushing air.

Examine the rest of the tube for evidence pin holes that look like they are about to go. If a bad tube you may find evidence everywhere. Scuff marks is a sign the inner tube is sliding inside the tire under riding load a sign of too loose fitting tire.

Keeping a little air in the tube keeping minimally round helps avoid the patch edges lifting.

With a pen circle and look for any other potential pin holes and circle those as well. You have the option of patching those before they go or at lest aware the potential in a continuing slow leak after you patched one..

Once you have found the pin hole, you are ready to patch it. This step is the same procedure as any other puncture hole.

Don't remove the silver backing of the patch just yet. It is prudent to be fussy about cleanliness to prevent contaminating the the patch.

With a ball point pen circle the hole. In a dry run line the patch so the circle round the hole is right in the center of the patch and trace an outline. The resulting  template insures you can see what you're doing aiming the patch so the hole is dead center when your ready for the cement process.

With a scrapper such as a cheese grater like scrapper provided in the repair kit or some sand paper scrap the surface of the template clean to a clean dull mat finish. A dirty surface won't stick. Now your a ready to apply the cement.

Keep the cleaned area clean or the cement won't stick

If you're using a brand new kit, unscrew the cap. In the top is a little pin. Turn over and pierce the silver seal. Don't empty the container or you will end up a messy glob. Don't squeeze. Let the cement ooze out to a small glob right on the center of the ink circle. Replace the cap.

Spread the rubber of the tube to widen the hole letting the cement drain into it to help plug it. When spreading make sure you keep the cement clean or particles of grease and dirt contaminates  the cement. With a clean tool spread the cement covering beyond the perimeter of the template. Even a dry clean finger has your oily grease.

Make sure you allow the cement to dry sticky where patches stick best. Now you can tear off the silver backing of the patch.

It is not really necessary, but a helpful option to spread some cement on the underside and edges of the patch to insure you have covered your bases. Cleanness is accentual.

Eye up a line of site the center circle to the center of the patch and press on.  You will only have one shot at this because the cement will stick fast. Watch your eye angle coordination squares the patch exactly to the perimeter of the template.

Use a round edge of a clean tool pressing down the edges. Don't Concentrate so much on the center but the edges of the patch.

Before you reassemble the tire to prevent pin holes from forming again make sure the don't forget about direction of the drive arrow on the tire wall must correspond with the drive direction of your bike. Now the inner tube can be reassembled back into the tire and fit the tire the arrow pointing in the direction of peddling.

If the tire feels a bit tight difficulty getting on, when finally on, pump up to near minimum tire pressure.