Technical data for the production Sinclair C5 (1985). Where period sources disagree, the conflict is noted rather than resolved.
| Item | Value | Source |
|---|---|---|
| Vehicle class (UK) | Electrically Assisted Pedal Cycle (EAPC), 3-wheel | EAPC Regulations 1983; Unofficial Service Manual |
| Manufacturer | Sinclair Vehicles Ltd, Coventry | Owner's documents |
| Assembler | Hoover plc, Merthyr Tydfil, Wales | Museum Wales; Unofficial Service Manual fig. 10 |
| Launched | 10 January 1985, Alexandra Palace, London | Wikipedia; Twist & Go |
| Launch price | £399 + £29 delivery | Twist & Go magazine |
| Length | 1744 mm (5 ft 9 in) | Twist & Go spec panel; Wikipedia |
| Width | 744 mm (2 ft 5 in) | as above |
| Height | 795 mm (2 ft 7 in) | as above |
| Wheelbase | 1304 mm (4 ft 3 in) | as above |
| Ground clearance | 56 mm (2¼ in) | Twist & Go |
| Turning circle | 5800 mm (19 ft) – “about 2/3 that of a Mini” | 1985 sales brochure |
| Weight | 30 kg without battery; ~45 kg with one 15 kg battery | Service Manual; brochure |
| Max. gross weight (incl. driver) | 150 kg recommended | 2nd-gear.blogspot (from Milner/Newman data) |
| Boot | 1 cu ft (≈28 litres), integral, lockable | Brochure |
| Body | Injection-moulded polypropylene, two shells | Brochure; Wikipedia |
| Chassis | “Y-configuration” corrosion-protected steel spine, developed with Lotus; no separate suspension | Brochure |
| Wheels | Reinforced nylon (plastic) | Brochure |
| Steering | Under-seat handlebar (“steering bars”) beneath the knees, rod linkage to front fork | Brochure |
| Brakes | Front: caliper (bicycle-type) on front wheel. Rear: twin-shoe drum on one rear wheel only | Brochure; Twist & Go; Service Manual |
| Parking brake | Latch on rear brake lever | Brochure |
| Pedals | Bicycle-type cranks, chain drive to rear axle | Brochure |
| Item | Value |
|---|---|
| Overall length / width / height | 1744 mm (5′8½″) / 744 mm (2′5¼″) / 795 mm (2′7¼″) |
| Ground clearance | 56 mm (2¼″) |
| Rear track | 630 mm (2′0¾″) |
| Wheelbase | 1304 mm (4′3¼″) |
| Vehicle weight (without battery) | approx. 30 kg (66 lb) |
| Max. recommended gross weight | 150 kg (330 lb) |
| Boot capacity / max. load | 28 litres (1 cu ft) / 10 kg (22 lb) |
| Max. speed (electric drive) | 24 km/h (15 mph) |
| Motor | 250 W continuous, 4,100 rpm max. |
| Gearbox | Two-stage single-speed reduction unit, overall ratio 13:1 |
| Front brake | Cable-operated caliper brake with high-performance blocks |
| Rear brake | Cable-operated twin-shoe hub brake on the off-side (right-hand) wheel, with parking brake |
| Front wheel/tyre | 12½″ nylon composite wheel; 12½ × 2¼″ low-rolling-resistance tyre |
| Rear wheels/tyres | 16″ nylon composite wheels; 16 × 2″ low-rolling-resistance tyres |
| Tyre pressures | Front 2.1 bar (30 psi); rear 2.4 bar (35 psi) |
| Castor trail | 11 mm (7/16″) |
| Turning circle | 5.8 m (19 ft) |
| Pedal drive | Steel drive sprocket 42 T; rear sprocket with freewheel 20 T; chain ½″ pitch × ⅛″, 181 links |
| Bulbs | 12 V 5 W wedge base, type W10/5 (front and rear) |
| Fuses | Main 5 A, auxiliary 1 A; glass cartridge, 20 mm long |
| Battery | 12 V nominal, 36 Ah at the 5-hour rate, approx. 15 kg, 236 × 136 × 206 mm (9 5/16 × 5⅜ × 8⅛″), 6-cell |
| Fastener | Torque |
|---|---|
| Motor clamping bolt | 8 Nm (6 lb ft) |
| Head bearing and steering head lock nuts | 42 Nm (31 lb ft) |
| Crank axle bearing lock ring | 37 Nm (27 lb ft) |
| Steering stem nut | 11 Nm (8 lb ft) |
| Steering bar clamp nut | 8 Nm (6 lb ft) |
| LH rear wheel bolt | 25 Nm (18 lb ft) |
| RH rear wheel locknut | 25 Nm (18 lb ft) |
| Front wheel securing nuts | 22 Nm (16 lb ft) |
| Front brake blocks to caliper | 4 Nm (3.5 lb ft) |
| Point | Lubricant | Quantity |
|---|---|---|
| Wheel bearings, crank axle bearings, front fork and steering head bearing | General-purpose grease, −40 °C to +100 °C | 3.5 ml |
| Gearbox | Lithium/polyethylene-based semi-fluid grease, viscosity 14.5 s at 100 °C. The Unofficial Service Manual suggests Castrol LMB. | 5.0 ml |
| Chain, cables, steering and brake pivots | Light machine oil or lubricant spray, every 6 months | – |
| Item | Value |
|---|---|
| Motor type | 12 V DC permanent-magnet, brushed |
| Rating | 250 W continuous (legal maximum for the class) |
| Max. motor speed | 4100 rpm (no-load) |
| Wheel speed at max. revs | ~315 rpm at the rear wheels |
| Reduction | Two stages, ≈13:1 overall – epicyclic gearbox on the motor, then a toothed belt to the rear axle |
| Driven wheel | Left-hand rear wheel |
| Stall current | Up to ~140 A |
| Maker | Polymotor (Italy), part of the Philips group. The design came from a truck cooling-fan motor. It is not a washing-machine motor, despite the popular myth. |
| Top speed | 15 mph (24 km/h) on the level; Service Manual Table I gives 22 km/h |
| Item | Value |
|---|---|
| Battery | 12 V flat-plate semi-traction lead-acid, made for Sinclair by Oldham Batteries |
| Weight | 15 kg |
| Capacity | 36 Ah at the 5-hour rate (Service Manual also quotes 35 Ah) |
| Usable in service | 15–28 Ah depending on load |
| Depth of discharge | 80 % of 5-hour capacity |
| Cycle life | 300 cycles to 20 % capacity loss (as specified) |
| Compatible replacements | Oldham types 015 and 038 fit the original battery top/key switch (c5owners.com) |
| Charger | Potted hybrid unit. Two-stage constant-current then constant-voltage profile. Two SCRs phase-controlled; two LEDs (charging / finished) |
| Charge time | Typically 8 hours from fully discharged |
| Second battery | A second battery could be fitted (spare battery kit); range figures below |
Average-weight driver, motor only, no pedalling.
| Test | Result |
|---|---|
| Standing-start acceleration | 1.7 m/s² |
| 0–8 km/h | 1.8 s |
| 0–16 km/h | 6.9 s |
| Maximum speed | 22 km/h |
| Braking, dry, 16 km/h–0 | 3 m |
| Braking, dry, max speed–0 | 5.5 m |
| Braking, wet, 16 km/h–0 | 5 m |
The 1985 brochure shows a stopping distance of about 4.6 m (15 ft) from 24 km/h (15 mph) on a dry, level road.
| Configuration | Approx. range (motor only, cruising in the right-most green load segment) |
|---|---|
| 1 battery | ~13 miles (21 km) |
| 2 batteries used one after the other | ~25 miles (40 km) |
| 2 batteries wired in parallel | ~33 miles (52 km) |
Wheel sizes are a well-known source of confusion. Sinclair, the brochure and the actual rims all quote different figures.
| Front | Rear (×2) | |
|---|---|---|
| Owner's Handbook | 12½ in | 16 in |
| Brochure (as printed) | 317 mm × 57 mm | 406 mm × 51 mm |
| Original tyre sidewall | SINCLAIR 12½ x 2½, 62-203, Made in Thailand | SINCLAIR 16 x 2, 54-305, Made in Thailand |
| ISO/ETRTO bead seat (buy by this) | 203 mm (same as a 12½“ child's bike) | 305 mm (16” “Chopper”-type size) |
| Item | Value |
|---|---|
| System voltage | 12 V |
| Headlamp | 12 V, 5 W bulb in a body-moulded housing |
| Rear lamp | Tail lamp plus two reflectors in one cluster |
| Instrument pod | Two 5-segment LED bar graphs, plus a buzzer: left = motor load, right = battery state |
| Power control | Push button under the rubber of the left steering-bar grip (on/off relay control, no proportional throttle) |
| Light switch | Under the seat |
| Master switch | Key-operated “master security switch” that clips onto the battery top, with a manual emergency cut-out button |
| Pre-wired for | Indicators and horn (accessory kits plug into existing harness) |
See Electrical System for how the pod, ULA and control box work.
| Figure | Value | Note |
|---|---|---|
| Production line capacity | 50–56 vehicles per hour per line; up to ~8,000 a week planned | Museum Wales; Wikipedia |
| Built by early Jan 1985 | >2,500 | Wikipedia |
| Total built | ~12,000–14,000 | Sources disagree: RCAHMW and Twist & Go say ~12,000; Wikipedia says 14,000. Some later retellings say 17,000, which is poorly supported. |
| Production ended | August 1985 |