Triumph Thunderbird Abs 1600 vs Harley-Davidson Flstf

The Triumph Thunderbird Abs 1600 passes its MOT first time more often than the Harley-Davidson Flstf: 89.5% vs 89.0%, a 0.5-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 Flstf
First-time pass rate	89.5%	89.0%
Outright fail rate	6.9%	4.9%
Vs comparable bikes (age & mileage adjusted)	+3.3 pts	+3.6 pts
Engine size	1,600cc	1,450cc
Rank among all models	#1113 of 5428	#1269 of 5428
Median miles at test	11,650	12,480
MOT tests analysed	2,200	30,148
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 Flstf
Tyres & wheels	3%	1.0%
Lights & signalling	1.5%	2.4%
Brakes	2.6%	1.0%
Steering & suspension	1%	0.6%
Fuel & exhaust	0.3%	0.6%
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 Flstf
2018	91.2%	89.6%
2019	88.6%	88.6%
2020	92.8%	91.2%
2021	80.1%	90.4%
2022	87.7%	90.3%
2023	91.5%	89.7%
2024	89.7%	90.4%
2025	89.7%	91.8%

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 Flstf
0k-10k miles	92.0%	90.1%
10k-20k miles	88.8%	88.7%
20k-30k miles	83.2%	87.8%
30k-40k miles	86.9%	87.5%
40k-50k miles	100.0%	89.2%

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

Triumph Thunderbird Abs 1600 vs Harley-Davidson Flstf FAQ

answers computed from the data above · terms in the glossary

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

The Triumph Thunderbird Abs 1600 passes its MOT first time more often than the Harley-Davidson Flstf: 89.5% vs 89.0%, a 0.5-point lead. Adjusted for age, mileage and test class the two are level (+3.3 vs +3.6 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 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 Flstf fail its MOT on most?

Lights & signalling: 2.4% of Harley-Davidson Flstf MOT tests failed on it, then tyres & wheels (1.0%).

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

At 40k-50k miles the Triumph Thunderbird Abs 1600 passes first time more often: 100.0% for the Triumph Thunderbird Abs 1600 vs 89.2% for the Harley-Davidson Flstf.

TRIUMPH THUNDERBIRD ABS 1600 89.5% pass · 2,200 tests HARLEY-DAVIDSON FLSTF 89.0% pass · 30.1k tests

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