If you find a free bike you will want to check it is safe to ride. Here are a few things you can do to look for common problems. Bear in mind this does not guarantee the bike is safe so if you are unsure it may be best to take the bike to a professional for a check-over. To learn more about bicycle maintenance a good manual is essential: Amazon has a good selection.
Drop Test
Lift the bike a few inches off the ground and drop it (onto the wheels). Listen out for major creaks or rattles, which could indicate parts are loose or broken.
Wheels
Check there are no missing spokes – indicated by empty spoke-holes on the inside of the wheel’s rim. Lift the wheel off the ground and spin it gently. It should spin freely and pass the brake pads freely. Look out for bent wheels by watching if the distance from the rim to the brake pad changes markedly – it should not vary by more than a few mm. Look at the rims (the bit the tyre sits on). If the braking surface curves inwards they are worn out. Older wheels can become rusty. This usually doesn’t matter too much but if the rust is pronounced it may affect the braking and even the integrity of the wheel.
Tyres
Check the tread and sides of the tyre. If possible take the tyre off and check it from the inside to make sure there are no major holes. Cracks on the sides of the tyre are not usually serious. The tyre should feel firm and rubbery. If it is crumbly or feels very hard or soft it will probably need replaced.
Steering
Lift the front wheel and push the handlebar on one side. It should flop to the other side easily but not completely freely. If it needs more than a gentle nudge the bearings may need greased or replaced. Pull on the front brake and rock the bike back and forth on the front wheel. If you feel a sharp click the bearings are probably loose. Try riding the bike at a moderate pace with no hands. If the bike does not hold a straight path this usually indicates problems with the steering.
Brakes
Check the pads to make sure there is rubber on them. Most have a wear line. Pull on the levers to check that the cables pull through ok and make sure they aren’t rusty. It’s a good idea to replace the cables and housing. Look to see that the brakes pull in evenly on both sides, otherwise they are not working efficiently and will need adjusting. Make sure you test the brakes in use.
Frame
Look over the entire frame for cracks. Check the forks are straight. Check around the frame tubing joints. Turn the bike upside down and check underneath. Check that the braze-ons (the sticky-out bits that hold the brake and gear cables) are not likely to break off. Don’t worry too much about rust unless it is deep enough to have eaten into the tubing. Surface rust can be painted over or covered with tape and isn’t likely to cause any problems with the integrity of the bike.
Drive Train
Rust on the chain and sprockets will usually clean off. However, if they are worn out they will need replaced. Try riding the bike with the brakes pulled on to see if the chain skips or ride uphill. If the chain rings or sprockets have teeth shaped like a shark’s fin they will probably need replaced. Grab one crank (the bits that connect to the pedals) and try pulling it towards and away from you with some force. They should feel solid. If there is any looseness or clicking the bottom bracket may need tightened or replaced.
Gears
Check that they shift through all gears. Also check that the rear dérailleur (the gear shifter at the back of the bike) is hanging down straight and that in the lowest gear it is clear of the rear spokes – otherwise you may have a nasty crash!
Seat Post and Stem
Try adjusting the seat post’s height (you will probably need an alen key or adjustable spanner). It is quite common for the seat post and frame to seize together. Some WD40 or other penetrating oil may loosen it but not always. Quill stems can also seize so make sure the height of the handlebars can be adjusted if this is necessary.
Bolts
You obviously want to check they are tight but bear in mind there are some bolts and screws on a bike that shouldn’t be tightened excessively.
Pedals
Check they are intact and turn ok. Ideally they should turn smoothly on their own axle but not spin freely. If you hear a click or tapping sound when cycling it could be that the pedals need replaced. Pedals can seize into the cranks and are very hard to free so if you suspect the pedals need replaced take the bike to a shop to check they can be removed.
Common Problems to Look Out For
- tyres that are soft, crumbly or brittle
- seized seat post
- bent forks and or front wheel – the bike may have been in a crash
- worn-out rims that bow inwards or are very rusty
- missing spokes – check for holes inside rim
- worn out chain and sprockets that skip
- bent dérailleur hanger
- shark-fin shaped teeth on sprocket and chain-ring