Train all you like, but if you have a problem with your bike in a race it's going to put a serious dent in your time. All bikes pick up wear and tear - so all triathletes need to be aware of how to make repairs quickly. Follow this simple guide to DIY bike maintenance:
CHECK: Keep an eye on both tyres, checking for wear on the tread as well as cracks on the sidewalls that might indicate they have started to perish. Worn tyres lead to slower performance and punctures.
FIX IT: You need to replace damaged tyres immediately. Using your tyre levers you can fit the new tyre back onto the wheel carefully with the inner tube inside without puncturing it.
CHECK: The pedals and chain are attached to crank arms. You have two, a left and right one, and they are attached to the frame via the bottom bracket. Put the cranks at three and nine o'clock and then try to move them from side to side (across the bike frame). If they move and the bike doesn't, it's time for a new bottom bracket.
FIX IT: You can buy tools for this. Older bikes, with square taper axles and internal bearings inside the bottom bracket housing, need a crank puller and a bottom bracket bearings tool. On new systems take the crank off with Allen keys, then use the external bearing housing tool. Make sure you grease the threads with some anti-corrosion grease such as Copaslip.
CHECK: If a wheel still wobbles after you've checked it for dents and broken spokes, the wheel bearings may have gone. They hold the weight of the bike so they need replacing immediately.
FIX IT: For cup and cone units, remove the wheel, take out the bearings, replace with the same number of new ones from a bike shop, dab Teflon-coated grease on the balls and slot them in, slide the axle through with the other cup on, now tighten. For cartridge units, remove the wheel and help the bearings out with a screwdriver, put new ones in using a socket tool that fits the outer race bearing housing, now slide the axle through and tighten.
CHECK: The cassette teeth should be even but, as time goes on, they will wear on one side, becoming hooked and pointy. This means the chain won't run smoothly over the teeth and you may find that you start jumping sprockets. To check your chain, try lifting it from the chain-ring (at the point nearest the front wheel). If you can lift it more than 4mm, you should replace it.
FIX IT: Replace the cassette at the same time as the chain, as they wear together. It's important to get the correct chain length by wrapping the chain around the big ring on the front and the big ring at the back (but not going through the derailleurs) and then add two links to this. You need a chain tool to do this and lots of multi-tools have one. There are two different makes of chain: Sram are easier to replace because they have special links called 'power links' which make it easier to assemble/disassemble the chain. Shimano chains require that you use specific chain-linking pins and are more fiddly.
CHECK: Make sure this isn't loose by facing your bike with the front wheel between your knees, then apply the front brake and rock the bike from side to side. To tighten it, loosen the top cap and stem pinch bolts with an Allen key, turn the top cap half a turn at a time and now do the stem bolts up again when you've finished each turn.
FIX IT: You need to buy a new headset. To replace the old one undo the top cap, take off the stem and any spacer, drop the forks out of the bottom of the frame. Use a long screwdriver to tap against the lip of the bearing housing inside. Now on the new headset put the top and bottom bearing houses onto the headtube using a headset press tool (£20). Then insert the bearings and seals (with a bit of grease), ensuring they are the right way up and tighten. Now you can put the headset back together.
CHECK: If the knurled nut adjuster where the brake cable enters the brake is on maximum, the brake pads are dead. Now check if the brake cable outer's damaged or the cables are fraying.
FIX IT: Brake pads are easy to change with your tool kit. To replace brake cables remove the old cable by cutting off the crimped-on cable protector and pulling it through the outer. Now pull the outer from the frame. Measure the new cable using the old one as a guide. Thread it through the outer and retention pin, then down to the outer end caps. Tighten it with the knurled nut adjuster. Finally put the cable protector on the end using pliers to stop the cable from fraying.
CHECK: If the wheel is dented, or you have a broken spoke, it might wobble and your brakes could lock. Run your hands around the spokes like you're playing a harp. They should give off the same note, because they should all be under the same amount of tension.
FIX IT: To tighten spokes, use a spoke key to gently turn the spoke nipple next to the rim. Test after each 1/4 of a turn - the note should become higher as the spoke tightens. If a wheel is severely out of shape it needs truing. You can buy a machine for this but it's relatively cheap to ask your bike shop to do it.