What to look for when buying a used bicycle

1. Worn/untight groupset try to move each pedal forward (while bike stationary) and to either side. This part is crucial and expensive! If not absolutely tight, or if creaky noise, walk away!
2. Wheels: Are the wheels aligned?
a. Is each wheel straight? (lift, spin the wheel and observe the distance to the frame, minor deviations can be righted, so not too big a problem, but major wobbles are not good)
b. do the wheels spin freely? - stop quickly or roll on for a long time?
c. are the two wheels on the exact same path? a bike with "unparallel" wheels is no good.
3. Is the saddle post stuck? Try to losen it and extend the saddle post (adjust the saddle height). Don't forget to bring a tool for this
4. Gears - do they shift correctly? External gear: if the chain is rusty and stiff, a new chain means the back cogwheels will have to be renewed too. If internal gear: does it make a sound? crunch?
5. Could the bike be stolen? Ask for the original receipt. and get a new receipt with frame number, when/if you buy it.
6. Tires - are they OK? Or does the price reflect their state? a new tyre costs c. 20 euro
7. Is the frame intact, without dents, big scratches/rust?
8. Brakes - do they work? test them. Also try pushing the bike gently forward and backward while braking the front wheel, is the headset bearing tight or loose?
9. Take a ride - and test some of the points above