Lights and Reflectors

How many lumens do I need on a bike light?

Lumens only matter alongside where the beam goes. On lit roads, 100 to 400 lumens with a shaped beam is enough to be seen and to spot potholes; unlit lanes want 600 to 1,000; technical singletrack at speed wants 1,500 or more, usually split between a bar light for the trail and a helmet light that points where you look. German StVZO-approved lamps such as the Busch + Müller Ixon range use a cut-off beam that puts light on the road without dazzling oncoming traffic, which is a different design goal from a round-beam trail light. Rear lights need far less output, and a steady rear plus a flashing one is a common set-up.

Do I still need reflectors?

Reflectors work without power and cost nothing in weight, so a rear reflector and pedal reflectors are a sensible backup even on a bike with good lights. They are passive, though, and only work when something is shining at them, so they do not replace lights on an unlit road. Bells and reflectors both turn up in the same clear-outs — the bike accessories section is the place to check if you are kitting out a commuter from scratch.

What should I check when buying used bike lights?

Batteries are the weak point. Lithium cells lose capacity with charge cycles and with being stored flat, so ask how old the light is and how long it runs on full power now, not when new — a claimed two-hour burn time often halves after three winters. Check the USB or charge port for corrosion and for a rubber cover that still seals, since a light with a perished port cover will fill with road spray and die. Look for condensation inside the lens, which means the seal has failed. Test the mounting bracket, as the moulded plastic clips and rubber O-ring straps crack with UV and cold, and brackets are model-specific and often unavailable. On lights with a separate battery pack, inspect the cable where it exits the pack for kinks and check the connector pins are not bent.

How much should I pay for used bike lights?

Judge the price on remaining battery life, not on the original price. A quality light with a healthy battery is worth around half of new; one with a tired battery is worth what a lens and a bracket are worth, which is very little unless the cells are user-replaceable or the light runs from standard 18650s. Buy new when you need reliable, all-winter commuting output and a warranty on the cells, and buy used for a second bike, a spare rear light or a trail lamp you will use a handful of nights a year. Dynamo headlights are the exception — they have no battery to degrade and used examples in good condition are a genuine bargain.