Derbi Senda SM vs Piaggio NRG

The Piaggio NRG passes its MOT first time more often than the Derbi Senda SM: 65.5% vs 51.1%, a 14.4-point lead.

MOT reliability, side by side

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

Metric	Derbi Senda SM	Piaggio NRG
First-time pass rate	51.1%	65.5%
Outright fail rate	35.5%	27.4%
Vs comparable bikes (age & mileage adjusted)	-21.0 pts	-6.0 pts
Engine size	49cc	49cc
Rank among all models	#5388 of 5428	#4992 of 5428
Median miles at test	10,212	9,874
MOT tests analysed	1,013	40,458
Most common failure	lighting and signalling	lighting and signalling

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 Senda SM	Piaggio NRG
Lights & signalling	27.8%	15.0%
Steering & suspension	16.9%	15.5%
Brakes	15.7%	10.2%
Tyres & wheels	4.0%	4.7%
Drive system	8.7%	0.0%
Structure & body	4.5%	2.5%
Fuel & exhaust	2.9%	3.8%

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 Senda SM	Piaggio NRG
2010	40.5%	63.2%
2011	46.2%	63.9%
2012	54.2%	63.4%
2013	51.6%	64.1%
2014	44.4%	67.4%
2015	57.8%	68.8%
2016	45.6%	68.0%
2017	61.2%	72.0%

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	Derbi Senda SM	Piaggio NRG
0k-10k miles	53.6%	71.3%
10k-20k miles	49.5%	60.6%
20k-30k miles	44.4%	55.7%

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

Derbi Senda SM vs Piaggio NRG FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Derbi Senda SM or the Piaggio NRG?

The Piaggio NRG passes its MOT first time more often than the Derbi Senda SM: 65.5% vs 51.1%, a 14.4-point lead. Adjusted for age, mileage and test class, the Piaggio NRG still comes out ahead: -21.0 points vs comparable bikes for the Derbi Senda SM, -6.0 for the Piaggio NRG. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Derbi Senda SM fail its MOT on most?

Lights & signalling: 27.8% of Derbi Senda SM MOT tests failed on it, then steering & suspension (16.9%).

What does the Piaggio NRG fail its MOT on most?

Steering & suspension: 15.5% of Piaggio NRG MOT tests failed on it, then lights & signalling (15.0%).

Which holds up better at high mileage, the Derbi Senda SM or the Piaggio NRG?

At 20k-30k miles the Piaggio NRG passes first time more often: 44.4% for the Derbi Senda SM vs 55.7% for the Piaggio NRG.

DERBI SENDA SM 51.1% pass · 1,013 tests PIAGGIO NRG 65.5% pass · 40.5k tests

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