The pass rate is the MOT first-time pass: a roadworthiness check of the items an MOT covers (brakes, lights, tyres, steering, structure, emissions), not a full mechanical inspection of engine or gearbox internals. It is a reliability signal, not a complete measure of mechanical reliability. What this measures.
Pass rate over time
The NH's first-time pass rate has fallen 6.4 points since 2006, 94.2% to 87.8%.
Pass rate by mileage
A low-mileage NH passes first time 91.7% of the time; by 20k that's 87.8%.
First-time pass rate by odometer reading at test, 10,000-mile bands for this model. Mileage is the strongest reliability signal. See the full curve.
What fails on a NH
| Component group | Share of defects | Defects | % of defects |
|---|---|---|---|
| lighting and signalling |
|
6 | 42.9 |
| steering and suspension |
|
4 | 28.6 |
| brakes |
|
3 | 21.4 |
| tyres and wheels |
|
1 | 7.1 |
Defects recorded against failed normal tests, 2005–2025, grouped by DVSA inspection section. One test can record multiple defects.
How rivals compare
On first-time pass rate the NH beats 4 of its 4 closest rivals (SUZUKI AN400, SUZUKI DR-Z400S, YAMAHA RD350).
Rivals share this bike's type and sit within ±30% of its engine capacity, ≥ 5,000 tests. Card colour = better/worse first-time pass rate than the NH.
Compare with any bike
More ARIEL models
Pass rate by registration year
Best year to buy used: 1957 (95.3% pass). Weakest: 1955 (94.6%).
First-time pass rate by the year each bike was first registered (cohorts with ≥ 50 tests). Older cohorts are survivors: the worst examples have already left the road, which tends to lift the earliest years.
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