Moto Guzzi V9 Bobber vs Triumph Thunderbird

The Triumph Thunderbird passes its MOT first time more often than the Moto Guzzi V9 Bobber: 87.8% vs 87.3%, a 0.5-point lead.

MOT reliability, side by side

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

Metric	Moto Guzzi V9 Bobber	Triumph Thunderbird
First-time pass rate	87.3%	87.8%
Outright fail rate	4.7%	6.2%
Vs comparable bikes (age & mileage adjusted)	-2.3 pts	+2.1 pts
Engine size	853cc	885cc
Rank among all models	#1818 of 5428	#1669 of 5428
Median miles at test	4,019	13,106
MOT tests analysed	716	56,312
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

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

Component	Moto Guzzi V9 Bobber	Triumph Thunderbird
Lights & signalling	2.4%	2.2%
Brakes	1.0%	2.0%
Tyres & wheels	0.3%	1.6%
Steering & suspension	0.3%	1.3%
Structure & body	0.4%	0.3%
Fuel & exhaust	0%	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	Moto Guzzi V9 Bobber	Triumph Thunderbird
2019	87.1%	87.7%
2020	90.1%	88.8%
2021	82.4%	88.2%
2022	87.7%	88.9%
2023	85.0%	90.5%
2024	88.8%	88.2%
2025	90.0%	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	Moto Guzzi V9 Bobber	Triumph Thunderbird
0k-10k miles	87.5%	90.5%
10k-20k miles	87.6%	87.3%

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

Moto Guzzi V9 Bobber vs Triumph Thunderbird FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Moto Guzzi V9 Bobber or the Triumph Thunderbird?

The Triumph Thunderbird passes its MOT first time more often than the Moto Guzzi V9 Bobber: 87.8% vs 87.3%, a 0.5-point lead. Adjusted for age, mileage and test class, the Triumph Thunderbird still comes out ahead: -2.3 points vs comparable bikes for the Moto Guzzi V9 Bobber, +2.1 for the Triumph Thunderbird. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Moto Guzzi V9 Bobber fail its MOT on most?

Lights & signalling: 2.4% of Moto Guzzi V9 Bobber MOT tests failed on it, then brakes (1.0%).

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%).

MOTO GUZZI V9 BOBBER 87.3% pass · 716 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.