Data as of: DVSA MOT results to 2025
Harley-Davidson XL vs Triumph Bonneville
The Triumph Bonneville passes its MOT first time more often than the Harley-Davidson XL: 89.0% vs 87.9%, a 1.1-point lead.
MOT reliability, side by side
| Metric | Harley-Davidson XL | Triumph Bonneville |
|---|---|---|
| First-time pass rate | 87.9% | 89.0% |
| Outright fail rate | 5.3% | 5.0% |
| Vs comparable bikes (age & mileage adjusted) | -0.1 pts | +1.6 pts |
| Engine size | 883cc | 865cc |
| Rank among all models | #1639 of 5428 | #1269 of 5428 |
| Median miles at test | 6,108 | 7,619 |
| MOT tests analysed | 18,541 | 195,256 |
| Most common failure | lamps and reflectors | 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.
"Vs comparable bikes" is the first-time pass rate minus the rate expected for each bike's own mix of age, mileage and test class, in percentage points: positive means better than comparable bikes. How this works.
What fails, side by side
| Component | Harley-Davidson XL | Triumph Bonneville |
|---|---|---|
| Lights & signalling | 3.0% | 1.9% |
| Brakes | 0.8% | 1.9% |
| Steering & suspension | 0.9% | 0.7% |
| Tyres & wheels | 0.5% | 1.1% |
| Structure & body | 1.0% | 0.5% |
| Fuel & exhaust | 0.1% | 0.3% |
| Drive system | 0.0% | 0.1% |
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 | Harley-Davidson XL | Triumph Bonneville |
|---|---|---|
| 2018 | 87.1% | 88.7% |
| 2019 | 86.5% | 88.9% |
| 2020 | 89.4% | 91.1% |
| 2021 | 88.8% | 89.6% |
| 2022 | 88.5% | 89.4% |
| 2023 | 88.4% | 90.1% |
| 2024 | 87.6% | 90.6% |
| 2025 | 87.5% | 91.0% |
Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.
Pass rate by mileage
| Mileage | Harley-Davidson XL | Triumph Bonneville |
|---|---|---|
| 0k-10k miles | 89.0% | 90.6% |
| 10k-20k miles | 85.5% | 86.8% |
| 20k-30k miles | 85.6% | 85.1% |
| 30k-40k miles | 83.6% | 85.8% |
| 40k-50k miles | 82.3% | 86.0% |
Bands with fewer than 30 tests for either bike are left out.
Harley-Davidson XL vs Triumph Bonneville FAQ
Which is more reliable, the Harley-Davidson XL or the Triumph Bonneville?
The Triumph Bonneville passes its MOT first time more often than the Harley-Davidson XL: 89.0% vs 87.9%, a 1.1-point lead. Adjusted for age, mileage and test class, the Triumph Bonneville still comes out ahead: -0.1 points vs comparable bikes for the Harley-Davidson XL, +1.6 for the Triumph Bonneville. An MOT checks roadworthiness items, not engine or gearbox internals.
What does the Harley-Davidson XL fail its MOT on most?
Lights & signalling: 3.0% of Harley-Davidson XL MOT tests failed on it, then structure & body (1.0%).
What does the Triumph Bonneville fail its MOT on most?
Lights & signalling: 1.9% of Triumph Bonneville MOT tests failed on it, then brakes (1.9%).
Which holds up better at high mileage, the Harley-Davidson XL or the Triumph Bonneville?
At 40k-50k miles the Triumph Bonneville passes first time more often: 82.3% for the Harley-Davidson XL vs 86.0% for the Triumph Bonneville.
See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.