ARIEL SQUARE FOUR

1000cc Petrol Class 2

#587 of 5426 overall #7 of 10 ARIELs #357 of 2787 other bikes

91.4%

first-time pass rate

2.0%

failed outright

11,764

median miles at test

555

MOT tests, 2005–2025

Pass rate over time

first-time pass rate by test year · 2006–2012

The SQUARE FOUR's first-time pass rate has held steady since 2006 (93.4% → 92.6%).

Pass rate by mileage

how the SQUARE FOUR's first-time pass rate falls with the odometer · class average 84.9%

A low-mileage SQUARE FOUR passes first time 89.5% of the time; by 50k that's 94.7%.

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 SQUARE FOUR

failure defects by component group · advisories excluded

Component group	Defects	% of defects	vs all bikes
brakes	6	37.5	0.2×
steering and suspension	4	25	0.2×
lighting and signalling	3	18.8	0.1×
tyres and wheels	2	12.5	0.1×
lamps and reflectors	1	6.2	0.1×

Defects recorded against failed normal tests, 2005–2025, grouped by DVSA inspection section. One test can record multiple defects. "vs all bikes" is how often this model's tests record a defect in the group, as a multiple of the all-bike rate.

How rivals compare

same type, similar capacity, high test volume

On first-time pass rate the SQUARE FOUR beats 3 of its 4 closest rivals (BMW R1200, BMW R1150, TRIUMPH SPRINT).

BMW R1200 92.9% pass · 299k tests BMW R1150 88.5% pass · 171k tests TRIUMPH SPRINT 85.6% pass · 133k tests SUZUKI GSF1200 82.4% pass · 97.6k tests

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 SQUARE FOUR.

Pass rate by registration year

how each model-year cohort fares · registration year from first use date

Best year to buy used: 1958 (93.5% pass). Weakest: 1957 (91.1%).

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.

ARIEL SQUARE FOUR FAQ

answers computed from the data above · terms in the glossary

Is the ARIEL SQUARE FOUR reliable?

The ARIEL SQUARE FOUR is more reliable than average for its class: 91.4% of its 555 MOT tests (2005–2025) passed first time, against a class average of 84.9%. That ranks it #587 of 5426 models.

What does a SQUARE FOUR fail its MOT on most?

brakes — 38% of all defects recorded against failed SQUARE FOUR tests.

What is the best year of SQUARE FOUR to buy used?

By first-time pass rate, 1958-registered examples do best (93.5%) and 1957 worst (91.1%). Condition and history still trump the year.

How many miles will a SQUARE FOUR last?

The median SQUARE FOUR shows 11,764 miles at test, and examples around 50k miles still pass 94.7% of the time — mileage alone rarely kills one.