Callipers
Browse used callipers for sale from riders across the UK. Digital, dial and vernier callipers measure outside, inside and depth dimensions, typically over a 150mm range and reading to 0.01mm — enough to separate a 27.2mm seatpost from a 27.0mm one, or a worn 1.5mm rotor from a serviceable one. They are for anyone buying parts secondhand or servicing their own bearings and headsets.
Digital, dial or vernier — which should I buy?
Digital callipers read straight off a screen, switch between millimetres and inches, and zero anywhere along the beam, which makes comparative measurement easy; they also drain button cells and dislike damp. Dial callipers need no battery and give a needle you can watch move, but one grain of grit in the rack will jam the mechanism. A vernier scale never fails and never needs anything, at the cost of good light and a second's reading. Mitutoyo is the reference name across all three, and workshop-grade tools from Draper or Sealey are accurate enough for bike work.
Calliper or chain checker?
They answer different questions. A chain checker drops into the links and gives a wear percentage in a second, which is the one measurement taken often enough to deserve a dedicated gauge. A calliper handles everything else: steerer and seatpost diameters, rotor and pad thickness, axle length, bearing inner and outer diameters, and the stack heights you work out before ordering a headset part. Most home workshops end up with both, alongside the rest of the measurement tools.
What should I check when buying used callipers?
Close the jaws fully and hold them up to a light — any visible gap means the jaws are worn or bent, and every reading after that is wrong. Slide the moving jaw through its full travel feeling for tight spots, then rock it side to side; play there is the damage a dropped calliper carries. On a digital tool, open the battery bay and look for corrosion, and watch whether the display drifts or flickers as you slide. Check the depth rod is straight and the locking screw still bites, and if the seller allows it, measure something of known size, such as a new brake rotor at 1.8mm.
Is a used calliper worth buying?
A precision calliper lasts decades provided nobody drops it, so a used Mitutoyo at half price beats a new budget tool — the difference is in jaw hardness and slide fit, not the number of decimal places on the display. Very cheap digital callipers are so inexpensive new that the used market barely applies to them. Buy new if you need a documented calibration, because a secondhand tool arrives with no history at all.