Gravel Bikes
Used gravel bikes are drop-bar bikes built for mixed terrain — tarmac, gravel tracks, bridleways and light off-road — with wider tyre clearance of 40-50mm, relaxed geometry and mount points for bags separating them from road bikes. The Specialized Diverge, Canyon Grail, Trek Checkpoint, Cannondale Topstone and Giant Revolt are the big sellers, and the category ranges from road-biased fast gravel bikes to near-MTB adventure rigs. Gravel is the fastest-growing segment in cycling and used bikes move quickly.
Road-biased or off-road-biased?
Gravel bikes sit on a spectrum. Road-biased gravel bikes (Cervélo Áspero, 3T Exploro, BMC URS) have tighter geometry, narrower tyre clearance of 38-42mm, and prioritise speed on smoother surfaces. Off-road-biased bikes (Salsa Cutthroat, Bombtrack Beyond, Surly Midnight Special) have slacker geometry, wider clearance of 45-50mm and up, and more mount points for bikepacking. Most mainstream gravel bikes (Diverge, Grail, Checkpoint) sit in the middle. Think about where you will actually ride most — 70% road and 30% gravel needs a different bike from 70% off-road, and riders at the tarmac end of that range should also compare endurance bikes.
What tyre clearance and wheel size do I need?
Tyre clearance is the defining spec. 700c x 40mm is the standard gravel setup. Some frames also accept 650b wheels with tyres up to 2.1in — a fatter, more MTB-like setup for rough terrain. If the frame supports both wheel sizes, you can swap between 700c for road-heavy days and 650b for rough stuff. Tubeless is strongly recommended for gravel: lower pressures for grip without pinch flat risk. Gravel-specific tyres like the Panaracer GravelKing, WTB Riddler and Schwalbe G-One are designed for mixed conditions.
Should I choose 1x or 2x?
1x drivetrains dominate gravel — a single chainring with a wide-range cassette. SRAM pioneered this with Force and Rival XPLR (10-44 cassette range). Shimano GRX is the dedicated gravel groupset in both 1x and 2x versions. 1x is simpler, with no front derailleur and less to go wrong, but 2x gives a wider overall range and closer gear steps, which is better if you ride significant road sections. A 40T or 42T chainring with an 11-42 or 10-44 cassette covers most gravel riding. Shimano GRX levers have a wider hood shape and more flare than standard road levers for better control on rough ground.
What frame features matter?
Gravel frames are loaded with mount points: three bottle cages minimum, rack and mudguard eyelets, top-tube bag mounts, and fork cargo mounts for anything bags. Dropped chainstays and seatstays create mud clearance. Many gravel frames use a dropped bottom bracket, with 75-80mm of drop, for stability at speed on loose surfaces. Carbon gravel frames save weight, aluminium is tougher for bikepacking abuse, and steel and titanium offer comfort and repairability for remote adventures.
What should I check buying used?
Gravel bikes take more abuse than pure road bikes. Inspect the frame for stone chip damage, checking the down tube and chainstays especially. 1x chainrings and wide-range cassettes wear faster than 2x setups because of increased chain angles. Check dropper post function if fitted, increasingly common on gravel bikes, and verify the through-axle threads are not cross-threaded. Bikes with bikepacking-specific features — mount points, frame bags, dynamo hubs — command premiums used, and they are worth it if you actually tour.