Triumph Thunderbird Abs 1600 vs Harley-Davidson XL1200C

The Triumph Thunderbird Abs 1600 passes its MOT first time more often than the Harley-Davidson XL1200C: 89.5% vs 88.4%, a 1.1-point lead.

MOT reliability, side by side

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

Metric	Triumph Thunderbird Abs 1600	Harley-Davidson XL1200C
First-time pass rate	89.5%	88.4%
Outright fail rate	6.9%	5.7%
Vs comparable bikes (age & mileage adjusted)	+3.3 pts	+2.3 pts
Engine size	1,600cc	1,200cc
Rank among all models	#1113 of 5428	#1478 of 5428
Median miles at test	11,650	9,976
MOT tests analysed	2,200	15,738
Most common failure	brakes	lighting and signalling

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 Thunderbird Abs 1600	Harley-Davidson XL1200C
Tyres & wheels	3%	1.1%
Lights & signalling	1.5%	2.5%
Brakes	2.6%	1.2%
Steering & suspension	1%	0.8%
Fuel & exhaust	0.3%	0.8%
Structure & body	0.2%	0.3%

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 Thunderbird Abs 1600	Harley-Davidson XL1200C
2018	91.2%	90.7%
2019	88.6%	89.2%
2020	92.8%	91.8%
2021	80.1%	90.0%
2022	87.7%	88.3%
2023	91.5%	88.7%
2024	89.7%	90.8%
2025	89.7%	88.9%

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 Thunderbird Abs 1600	Harley-Davidson XL1200C
0k-10k miles	92.0%	89.9%
10k-20k miles	88.8%	88.1%
20k-30k miles	83.2%	86.1%
30k-40k miles	86.9%	86.1%
40k-50k miles	100.0%	80.3%

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

Triumph Thunderbird Abs 1600 vs Harley-Davidson XL1200C FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Triumph Thunderbird Abs 1600 or the Harley-Davidson XL1200C?

The Triumph Thunderbird Abs 1600 passes its MOT first time more often than the Harley-Davidson XL1200C: 89.5% vs 88.4%, a 1.1-point lead. Adjusted for age, mileage and test class, the Triumph Thunderbird Abs 1600 still comes out ahead: +3.3 points vs comparable bikes for the Triumph Thunderbird Abs 1600, +2.3 for the Harley-Davidson XL1200C. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Triumph Thunderbird Abs 1600 fail its MOT on most?

Tyres & wheels: 3% of Triumph Thunderbird Abs 1600 MOT tests failed on it, then brakes (2.6%).

What does the Harley-Davidson XL1200C fail its MOT on most?

Lights & signalling: 2.5% of Harley-Davidson XL1200C MOT tests failed on it, then brakes (1.2%).

Which holds up better at high mileage, the Triumph Thunderbird Abs 1600 or the Harley-Davidson XL1200C?

At 40k-50k miles the Triumph Thunderbird Abs 1600 passes first time more often: 100.0% for the Triumph Thunderbird Abs 1600 vs 80.3% for the Harley-Davidson XL1200C.

TRIUMPH THUNDERBIRD ABS 1600 89.5% pass · 2,200 tests HARLEY-DAVIDSON XL1200C 88.4% pass · 15.7k tests

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