Data as of: DVSA MOT results to 2025
Ariel Square Four vs Triumph Sprint
The Ariel Square Four passes its MOT first time more often than the Triumph Sprint: 91.4% vs 85.6%, a 5.8-point lead.
MOT reliability, side by side
| Metric | Ariel Square Four | Triumph Sprint |
|---|---|---|
| First-time pass rate | 91.4% | 85.6% |
| Outright fail rate | 2.0% | 8.8% |
| Engine size | 1,000cc | 955cc |
| Rank among all models | #588 of 5428 | #2333 of 5428 |
| Median miles at test | 11,764 | 20,615 |
| MOT tests analysed | 555 | 132,827 |
| 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.
What fails, side by side
| Component | Ariel Square Four | Triumph Sprint |
|---|---|---|
| Brakes | 0.7% | 3.7% |
| Lights & signalling | 0.7% | 2.8% |
| Steering & suspension | 0.5% | 2.5% |
| Tyres & wheels | 0.2% | 2.2% |
| Structure & body | 0% | 0.6% |
| Drive system | 0% | 0.4% |
| Fuel & exhaust | 0% | 0.2% |
A test that fails on two components counts once in each. Component links go to the bikes most likely to fail on it.
Pass rate by test year
| Test year | Ariel Square Four | Triumph Sprint |
|---|---|---|
| 2006 | 93.4% | 87.0% |
| 2007 | 94.9% | 85.9% |
| 2008 | 89.2% | 84.8% |
| 2009 | 92.9% | 84.1% |
| 2010 | 91.2% | 84.6% |
| 2011 | 83.6% | 84.3% |
| 2012 | 92.6% | 84.5% |
Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.
Pass rate by mileage
| Mileage | Ariel Square Four | Triumph Sprint |
|---|---|---|
| 0k-10k miles | 89.5% | 90.9% |
| 10k-20k miles | 90.5% | 87.5% |
| 20k-30k miles | 90.0% | 85.0% |
| 30k-40k miles | 96.0% | 82.1% |
| 40k-50k miles | 97.5% | 80.3% |
| 50k-60k miles | 94.7% | 79.3% |
Bands with fewer than 30 tests for either bike are left out.
Ariel Square Four vs Triumph Sprint FAQ
Which is more reliable, the Ariel Square Four or the Triumph Sprint?
The Ariel Square Four passes its MOT first time more often than the Triumph Sprint: 91.4% vs 85.6%, a 5.8-point lead. An MOT checks roadworthiness items, not engine or gearbox internals.
What does the Ariel Square Four fail its MOT on most?
Brakes: 0.7% of Ariel Square Four MOT tests failed on it, then lights & signalling (0.7%).
What does the Triumph Sprint fail its MOT on most?
Brakes: 3.7% of Triumph Sprint MOT tests failed on it, then lights & signalling (2.8%).
Which holds up better at high mileage, the Ariel Square Four or the Triumph Sprint?
At 50k-60k miles the Ariel Square Four passes first time more often: 94.7% for the Ariel Square Four vs 79.3% for the Triumph Sprint.
See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.