| MODEL | ARIEL LEADER 1958 |
| Year | 1958 |
| Engine Type | Twin, two-stroke |
| Displacement / Capacity | 249 cc / 15.19 cu in |
| Bore X Stroke | 54.0 x 54.0 mm / 2.1 x 2.1 in |
| Compression Ratio | — |
| Cooling System | Air |
| Max Power | 11.7 kW / 16 hp @ 6400 rpm |
| Max Torque | — |
| Ignition | — |
| Induction | — |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 4-speed |
| Clutch | — |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | Steel backbone |
| Front Suspension | Trailing link, oil-damped |
| Rear Suspension | Swingarm |
| Front Brakes | Drum, 152 mm / 6 in |
| Rear Brakes | Drum, 152 mm / 6 in |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | 762 mm / 30 in |
| Wheelbase | 1295 mm / 51 in |
| Ground Clearance | — |
| Dry Weight | 150 kg / 330.7 lb |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | 3.25-16 |
| Rear Tyre | 3.25-16 |
| FUEL SYSTEM | |
| Fuel Capacity | 9 Litres / 2.38 US gal |
| Fuel Consumption | 2.94 L/100 km / 80 mpg |
| Top Speed | 110 km/h / 68.4 mph |
The Leader was Ariel's fully enclosed 250 cc two-stroke twin, with a pressed-steel backbone frame, trailing-link forks, legshields and a windscreen. It was aimed at all-weather touring and commuting. The first year, with 16 hp.
