HARLEY-DAVIDSON SPORTSTER vs TRIUMPH THUNDERBIRD

The TRIUMPH THUNDERBIRD passes its MOT first time more often than the HARLEY-DAVIDSON SPORTSTER — 87.8% vs 84.6%, a 3.2-point lead.

MOT reliability, side by side

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

Metric	HARLEY-DAVIDSON SPORTSTER	TRIUMPH THUNDERBIRD
First-time pass rate	84.6%	87.8%
Outright fail rate	7.8%	6.2%
Median miles at test	12,867	13,106
MOT tests analysed	10,171	56,312
Most common failure	lighting and signalling	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.

HARLEY-DAVIDSON SPORTSTER 84.6% pass · 10.2k 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.