Harley-Davidson XL 1200 T Superlow SPORTSTER18 vs Triumph Bonneville

The Harley-Davidson XL 1200 T Superlow SPORTSTER18 passes its MOT first time more often than the Triumph Bonneville: 94.1% vs 89.0%, a 5.1-point lead.

MOT reliability, side by side

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

Metric	Harley-Davidson XL 1200 T Superlow SPORTSTER18	Triumph Bonneville
First-time pass rate	94.1%	89.0%
Outright fail rate	1.7%	5.0%
Vs comparable bikes (age & mileage adjusted)	+5.7 pts	+1.6 pts
Engine size	1,202cc	865cc
Rank among all models	#153 of 5428	#1269 of 5428
Median miles at test	6,724	7,619
MOT tests analysed	290	195,256
Most common failure	tyres	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.

Pass rate by test year

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

Test year	Harley-Davidson XL 1200 T Superlow SPORTSTER18	Triumph Bonneville
2021	87.9%	89.6%
2022	95.4%	89.4%
2023	95.5%	90.1%
2024	97.9%	90.6%
2025	94.0%	91.0%

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 1200 T Superlow SPORTSTER18	Triumph Bonneville
0k-10k miles	94.7%	90.6%
10k-20k miles	92.3%	86.8%

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

HARLEY-DAVIDSON XL 1200 T SUPERLOW SPORTSTER18 94.1% pass · 290 tests TRIUMPH BONNEVILLE 89.0% pass · 195k tests

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