The Brompton C Line 12-speed (2025) is a folding bike — representative silhouette: Folding. We have read 1 specification sheet (Brompton Bicycle) and recorded 5 fit facts from it. 2 of the 14 measurements a folding bike needs to answer fit questions are on file; 0 are confirmed by two independent sources. Where a measurement is missing, we say so below — we do not guess.
| Wheel size (ISO bead seat) | 16" Brompton / 16 × 1 3/8 (ISO 349) |
|---|---|
| Rotor interface (hubs) | No rotor interface (rim brake) |
| Brake actuation | Cable rim brake |
| Brake pad shape (fitted calipers) | Rim pads: Brompton dual-pivot caliper |
| Shift actuation | Mechanical (cable) |
Confidence: every fact above comes from a single cited source — "derived" on our lattice; none is verified by a second independent publisher yet. A verdict that rests on a safety-critical fact therefore stops at "unknown" rather than "fits".
Not on file (required for a folding bike): Bottom bracket shell · Derailleur hanger · Rear axle spacing · Seatpost diameter · Maximum tyre width (frame) · Front axle spacing · Brake mount, front · Brake mount, rear · Freehub body · Rear speeds · Chain standard · Pedal thread. The sheet we read does not state them; until a source does, every fit question that needs one of these reads "unknown" — or "unknown — safety-critical" where a guess could hurt you.
- Why do so many verdicts on this bike read "unknown"?
- Because a verdict needs the bike's measurement for every dimension a part requires, and 12 of the 14 required measurements are not on file. "Unknown" means we could not check — not that it fits, and not that it does not.
- Will the verdicts change?
- Yes. When a second independent source confirms a measurement — or a first one states a missing one — the verdicts are recomputed from the new facts. Nothing on this page is typed by hand.