Brakes and tyres work by creating friction. Anything that reduces that friction such as worn brake pads or bald tyres will increase the vehicle's stopping distance.
Also drivers and cycle riders need to take extra care in bad weather such as ice and rain. Sometimes the road surface itself can be worn or uneven.
Keeping your vehicle in good condition
Overhaul your or a friend's bicycle. Check for cracks and bald patches on the tyres. Are they pumped up enough? Are the brake blocks worn away? What about places where you don't want friction? Oil the axles, chain, gears and cables.
Case study: A city transport system