Ariel Square Four
77/100 Overall
58 On the road95 As a classic
Classic motorcycle head-to-head
Ariel Square Four vs Triumph Bonneville T120
Ariel Square Four scores 77/100 overall against Triumph Bonneville T120 on 82/100. On the road: 58–65. As classics: 95–98. Overall result: Triumph Bonneville T120.
Triumph Bonneville T120
82/100 Overall
65 On the road98 As a classic
The numbers
Category-by-category result
| Category | Ariel Square Four | Triumph Bonneville | Advantage |
|---|---|---|---|
| road | |||
| PerformanceDirect comparison of power, acceleration and usable performance across the pre-1990 classic field. | 7 | 6 | Ariel Square Four |
| HandlingSteering, stability, weight and real-road manners. | 6 | 8 | Triumph Bonneville |
| BrakingDirect comparison of real stopping ability without an age allowance. | 4 | 5 | Triumph Bonneville |
| ReliabilityEngine, electrics and general dependability when properly maintained. | 5 | 6 | Triumph Bonneville |
| Ease of ownershipMaintenance, parts supply and access to specialist knowledge. | 5 | 8 | Triumph Bonneville |
| ComfortRiding position, vibration and suitability for longer journeys. | 8 | 6 | Ariel Square Four |
| classic | |||
| StylingDesign quality, visual presence and period appeal. | 9 | 10 | Triumph Bonneville |
| Historical importanceInfluence on motorcycling and importance within its era. | 10 | 10 | Level |
| Collector appealLong-term desirability among classic motorcycle enthusiasts. | 9 | 9 | Level |
| CharacterSound, feel, personality and memorable riding experience. | 10 | 10 | Level |
Choose the Ariel Square Four if…
you want unique engineering, refined four-cylinder character and one of Britain's most distinctive luxury motorcycles.
Choose the Triumph Bonneville if…
you value lightness, accessible mechanical simplicity and the sound and feel of a classic British twin.
Background
History
Ariel Square Four
The Ariel Square Four was produced from 1931–1959 and used a air-cooled square-four engine. Within this comparison library it stands out particularly for historic importance, character, styling. It suits riders who value the qualities described in its original profile rather than choosing by specification alone.
Triumph Bonneville
The Triumph Bonneville T120 was produced from 1959–1973 and used a 649cc air-cooled parallel twin. Within this comparison library it stands out particularly for styling, historic importance, character. It suits riders who value the qualities described in its original profile rather than choosing by specification alone.
Interesting details
Did you know?
Ariel Square Four
- Its production span in this library runs from 1931 to 1959.
- The recorded engine description is: air-cooled square-four engine.
- Its strongest comparison scores are historic importance, character, styling.
Triumph Bonneville
- Its production span in this library runs from 1959 to 1973.
- The recorded engine description is: 649cc air-cooled parallel twin.
- Its strongest comparison scores are styling, historic importance, character.
Present-day appeal
Collector notes
Ariel Square Four
Collector interest is strongest where condition, originality and correct period details support the identity of the Ariel Square Four. Its library score for historic importance is 10/10. Values and desirability can vary substantially between years, specifications and restoration quality, so individual examples should be assessed on their own evidence.
Triumph Bonneville
Collector interest is strongest where condition, originality and correct period details support the identity of the Triumph Bonneville T120. Its library score for styling is 10/10. Values and desirability can vary substantially between years, specifications and restoration quality, so individual examples should be assessed on their own evidence.
Before you buy
Buying checks
Ariel Square Four
- Confirm the frame and engine identity match the advertised model and year.
- Check cold starting, smoke, oil leaks and unusual mechanical noise.
- Inspect the frame, wheels, brakes and suspension for wear, damage or poor repairs.
- Verify that important model-specific parts have not been replaced with incorrect later components.
- Review the paperwork, ownership history and any restoration invoices before purchase.
Triumph Bonneville
- Confirm the frame and engine identity match the advertised model and year.
- Check cold starting, smoke, oil leaks and unusual mechanical noise.
- Check vibration-related fasteners, primary drive condition and signs of persistent oil leakage.
- Inspect the frame, wheels, brakes and suspension for wear, damage or poor repairs.
- Verify that important model-specific parts have not been replaced with incorrect later components.
- Review the paperwork, ownership history and any restoration invoices before purchase.
Period opposition
Historic rivals
Rivals to the Ariel Square Four
Rivals to the Triumph Bonneville
Final result
The verdict
Triumph Bonneville T120 wins the direct on-the-road comparison. Triumph Bonneville T120 wins the classic-motorcycle comparison. Triumph Bonneville T120 takes the overall result after the road and classic scores are weighted equally.