Components
Browse used city bike components for sale from riders across the UK. City parts are chosen for weather, load and neglect rather than weight, so the category runs to 3, 7 and 8-speed hub gears, dynamo front hubs, full-length mudguards, rear racks, chainguards and puncture-belted tyres around 700x35c. It covers upgrades and replacements for commuters, hybrids and Dutch-style roadsters.
What makes a city component different?
A city rack is rated for something like 25kg of panniers, a city mudguard runs the full length of the wheel with a mudflap, and a chainguard exists purely to keep trouser hems out of the chain. The same parts in a road or mountain range would be lighter, more exposed and shorter-lived on a bike locked outside a station all day in the rain. Saddles are the single biggest comfort change on an upright bike, and those are listed separately under city saddles.
Hub gears or a derailleur?
A 3-speed hub covers flat towns, and a 7 or 8-speed hub covers most UK commuting, with an 8-speed giving roughly 300% range in even steps. Hub gears shift at a standstill at traffic lights, run sealed behind a chainguard and ask almost nothing of you, at the cost of weight and a more awkward rear wheel removal. Derailleur city bikes are lighter, cheaper to repair anywhere, and far easier to find second-hand parts for.
What wears out on used city parts?
Rust does most of the damage. Rack and mudguard stays crack where they bend at the eyelet, and bolts seize into aluminium and shear off when someone finally tries to remove them. Spin a dynamo front hub by hand and listen for grinding, then check the two spade terminals for corrosion and bending. A hub gear should shift cleanly through every gear with the cable marks aligned, and slipping under load points to internal wear rather than adjustment. On anything that clamps to a seatpost, check the post moves in the frame at all before you buy.
Will it fit my bike?
Four numbers settle most of it: seatpost diameter, commonly 27.2mm on steel frames; wheel size, 700c on most modern city bikes and 26in on older ones; rear hub spacing, usually 135mm; and mudguard clearance measured against the tyre you actually run rather than the one the frame was sold with. Rack fitting then depends on whether the frame has eyelets at the dropout and near the seatstay at all.
Used part or a whole used bike?
Hub gears, dynamo hubs and solid steel racks hold their value and are the parts genuinely worth buying second-hand. Cables, budget mudguards and plastic pedals are rarely worth the postage. If your list of parts adds up past a couple of hundred pounds, price a complete city bike before committing, and look through the wider city listings in case a donor bike costs less than the sum of its parts.