Derbi Terra 125 vs Yamaha YBR 125

The Yamaha YBR 125 passes its MOT first time more often than the Derbi Terra 125: 71.0% vs 67.7%, a 3.3-point lead.

MOT reliability, side by side

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

Metric	Derbi Terra 125	Yamaha YBR 125
First-time pass rate	67.7%	71.0%
Outright fail rate	24.3%	17.1%
Vs comparable bikes (age & mileage adjusted)	-5.7 pts	-1.1 pts
Engine size	124cc	124cc
Rank among all models	#4875 of 5428	#4664 of 5428
Median miles at test	6,802	10,652
MOT tests analysed	613	124,897
Most common failure	brakes	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 125	Yamaha YBR 125
Lights & signalling	12.6%	8.5%
Steering & suspension	11.3%	6.5%
Brakes	11.3%	5.9%
Drive system	6.4%	2.9%
Tyres & wheels	2.8%	4.4%
Structure & body	2.1%	3.8%
Fuel & exhaust	1.5%	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 125	Yamaha YBR 125
2012	66.1%	69.1%
2013	76.3%	69.5%
2014	60.2%	70.0%
2015	63.3%	71.2%
2016	72.1%	71.3%
2017	65.5%	70.7%

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 125	Yamaha YBR 125
0k-10k miles	71.3%	76.8%
10k-20k miles	61.2%	67.4%

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

Derbi Terra 125 vs Yamaha YBR 125 FAQ

answers computed from the data above · terms in the glossary

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

The Yamaha YBR 125 passes its MOT first time more often than the Derbi Terra 125: 71.0% vs 67.7%, a 3.3-point lead. Adjusted for age, mileage and test class, the Yamaha YBR 125 still comes out ahead: -5.7 points vs comparable bikes for the Derbi Terra 125, -1.1 for the Yamaha YBR 125. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Derbi Terra 125 fail its MOT on most?

Lights & signalling: 12.6% of Derbi Terra 125 MOT tests failed on it, then steering & suspension (11.3%).

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 125 67.7% pass · 613 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.