Derbi Terra vs Yamaha YBR 125

The Derbi Terra passes its MOT first time more often than the Yamaha YBR 125: 71.1% vs 71.0%, a 0.1-point lead.

MOT reliability, side by side

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

Metric	Derbi Terra	Yamaha YBR 125
First-time pass rate	71.1%	71.0%
Outright fail rate	16.5%	17.1%
Vs comparable bikes (age & mileage adjusted)	-2.9 pts	-1.1 pts
Engine size	124cc	124cc
Rank among all models	#4652 of 5428	#4664 of 5428
Median miles at test	5,586	10,652
MOT tests analysed	744	124,897
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	Derbi Terra	Yamaha YBR 125
Lights & signalling	9.0%	8.5%
Steering & suspension	5.9%	6.5%
Brakes	6.3%	5.9%
Structure & body	3.5%	3.8%
Tyres & wheels	2.2%	4.4%
Drive system	1.7%	2.9%
Fuel & exhaust	0.3%	0.6%

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	Derbi Terra	Yamaha YBR 125
2018	68.1%	72.0%
2019	73.2%	71.8%
2020	77.8%	73.4%
2021	70.0%	71.6%
2022	71.3%	71.3%
2023	66.7%	71.1%
2024	71.4%	70.9%
2025	71.8%	71.2%

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	Derbi Terra	Yamaha YBR 125
0k-10k miles	73.9%	76.8%
10k-20k miles	64.7%	67.4%

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

Derbi Terra vs Yamaha YBR 125 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Derbi Terra or the Yamaha YBR 125?

The Derbi Terra passes its MOT first time more often than the Yamaha YBR 125: 71.1% vs 71.0%, a 0.1-point lead. Adjusted for age, mileage and test class, the Yamaha YBR 125 still comes out ahead: -2.9 points vs comparable bikes for the Derbi Terra, -1.1 for the Yamaha YBR 125. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Derbi Terra fail its MOT on most?

Lights & signalling: 9.0% of Derbi Terra MOT tests failed on it, then brakes (6.3%).

What does the Yamaha YBR 125 fail its MOT on most?

Lights & signalling: 8.5% of Yamaha YBR 125 MOT tests failed on it, then steering & suspension (6.5%).

DERBI TERRA 71.1% pass · 744 tests YAMAHA YBR 125 71.0% pass · 125k tests

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