Triumph Bonneville 865 vs Triumph Thunderbird

The Triumph Bonneville 865 passes its MOT first time more often than the Triumph Thunderbird: 89.2% vs 87.8%, a 1.4-point lead.

MOT reliability, side by side

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

Metric	Triumph Bonneville 865	Triumph Thunderbird
First-time pass rate	89.2%	87.8%
Outright fail rate	4.6%	6.2%
Vs comparable bikes (age & mileage adjusted)	+2.3 pts	+2.1 pts
Engine size	865cc	885cc
Rank among all models	#1212 of 5428	#1669 of 5428
Median miles at test	8,536	13,106
MOT tests analysed	5,589	56,312
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.

"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

share of each bike's MOT tests that failed on the component · lower is better

Component	Triumph Bonneville 865	Triumph Thunderbird
Brakes	2.1%	2.0%
Lights & signalling	1.6%	2.2%
Tyres & wheels	1.1%	1.6%
Steering & suspension	0.4%	1.3%
Structure & body	0.3%	0.3%
Fuel & exhaust	0.1%	0.4%
Drive system	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

first-time MOT pass rate in each calendar year both bikes were tested

Test year	Triumph Bonneville 865	Triumph Thunderbird
2018	91.3%	87.8%
2019	89.5%	87.7%
2020	90.7%	88.8%
2021	92.0%	88.2%
2022	89.6%	88.9%
2023	87.8%	90.5%
2024	89.0%	88.2%
2025	90.2%	89.5%

Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.

Pass rate by mileage

first-time MOT pass rate by miles on the clock at test

Mileage	Triumph Bonneville 865	Triumph Thunderbird
0k-10k miles	90.7%	90.5%
10k-20k miles	88.7%	87.3%
20k-30k miles	86.8%	85.4%
30k-40k miles	81.0%	84.3%
40k-50k miles	80.2%	83.2%

Bands with fewer than 30 tests for either bike are left out.

Triumph Bonneville 865 vs Triumph Thunderbird FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Triumph Bonneville 865 or the Triumph Thunderbird?

The Triumph Bonneville 865 passes its MOT first time more often than the Triumph Thunderbird: 89.2% vs 87.8%, a 1.4-point lead. Adjusted for age, mileage and test class the two are level (+2.3 vs +2.1 points against comparable bikes), so the raw gap is mostly down to how old and how used each fleet is. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Triumph Bonneville 865 fail its MOT on most?

Brakes: 2.1% of Triumph Bonneville 865 MOT tests failed on it, then lights & signalling (1.6%).

What does the Triumph Thunderbird fail its MOT on most?

Lights & signalling: 2.2% of Triumph Thunderbird MOT tests failed on it, then brakes (2.0%).

Which holds up better at high mileage, the Triumph Bonneville 865 or the Triumph Thunderbird?

At 40k-50k miles the Triumph Thunderbird passes first time more often: 80.2% for the Triumph Bonneville 865 vs 83.2% for the Triumph Thunderbird.

TRIUMPH BONNEVILLE 865 89.2% pass · 5,589 tests TRIUMPH THUNDERBIRD 87.8% pass · 56.3k tests

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