Ariel Square Four vs BMW R1150

The Ariel Square Four passes its MOT first time more often than the BMW R1150 — 91.4% vs 88.5%, a 2.9-point lead.

MOT reliability, side by side

first-time pass rate, outright fail rate and tests analysed · 2005–2025

Metric	Ariel Square Four	BMW R1150
First-time pass rate	91.4%	88.5%
Outright fail rate	2.0%	6.8%
Median miles at test	11,764	33,151
MOT tests analysed	555	170,963
Most common failure	brakes	brakes

First-time outcomes on normal tests, 2005–2025. "Most common failure" is the component group with the most recorded defects on failed tests. Read pass rates against test counts: a smaller sample is noisier. Source: DVSA anonymised MOT results.

ARIEL SQUARE FOUR 91.4% pass · 555 tests BMW R1150 88.5% pass · 171k tests

See each bike's full report — trend, mileage curve, failure breakdown and rivals — on its own page.