Harley-Davidson XL vs Triumph Bonneville T 100 (865)

The Triumph Bonneville T 100 (865) passes its MOT first time more often than the Harley-Davidson XL: 89.6% vs 87.9%, a 1.7-point lead.

MOT reliability, side by side

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

Metric	Harley-Davidson XL	Triumph Bonneville T 100 (865)
First-time pass rate	87.9%	89.6%
Outright fail rate	5.3%	4.5%
Vs comparable bikes (age & mileage adjusted)	-0.1 pts	+2.4 pts
Engine size	883cc	865cc
Rank among all models	#1639 of 5428	#1077 of 5428
Median miles at test	6,108	7,832
MOT tests analysed	18,541	16,221
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	Harley-Davidson XL	Triumph Bonneville T 100 (865)
Lights & signalling	3.0%	1.4%
Brakes	0.8%	1.9%
Tyres & wheels	0.5%	1.0%
Structure & body	1.0%	0.3%
Steering & suspension	0.9%	0.3%
Fuel & exhaust	0.1%	0.4%
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

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

Test year	Harley-Davidson XL	Triumph Bonneville T 100 (865)
2018	87.1%	88.9%
2019	86.5%	90.3%
2020	89.4%	92.6%
2021	88.8%	90.1%
2022	88.5%	90.6%
2023	88.4%	89.9%
2024	87.6%	90.8%
2025	87.5%	90.4%

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	Harley-Davidson XL	Triumph Bonneville T 100 (865)
0k-10k miles	89.0%	91.1%
10k-20k miles	85.5%	87.9%
20k-30k miles	85.6%	85.4%
30k-40k miles	83.6%	84.4%
40k-50k miles	82.3%	86.4%

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

Harley-Davidson XL vs Triumph Bonneville T 100 (865) FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Harley-Davidson XL or the Triumph Bonneville T 100 (865)?

The Triumph Bonneville T 100 (865) passes its MOT first time more often than the Harley-Davidson XL: 89.6% vs 87.9%, a 1.7-point lead. Adjusted for age, mileage and test class, the Triumph Bonneville T 100 (865) still comes out ahead: -0.1 points vs comparable bikes for the Harley-Davidson XL, +2.4 for the Triumph Bonneville T 100 (865). 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 T 100 (865) fail its MOT on most?

Brakes: 1.9% of Triumph Bonneville T 100 (865) MOT tests failed on it, then lights & signalling (1.4%).

Which holds up better at high mileage, the Harley-Davidson XL or the Triumph Bonneville T 100 (865)?

At 40k-50k miles the Triumph Bonneville T 100 (865) passes first time more often: 82.3% for the Harley-Davidson XL vs 86.4% for the Triumph Bonneville T 100 (865).

HARLEY-DAVIDSON XL 87.9% pass · 18.5k tests TRIUMPH BONNEVILLE T 100 (865) 89.6% pass · 16.2k tests

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