UN R41 Supplement 4 (05 series) · UNECE Regulation No. 41 (ECE R41) — Uniform provisions concerning the approval of motorcycles with regard to noise.
UN R41 — Supplement 4 to the 05 series of amendments
Supplement 3 → 4
- What changed
- The rule in paragraph 6.3.1. against a device or procedure used to pass the noise tests now also names software.
- Annex 7 has new speed tolerances in paragraph 2.8. and new rules for the number of additional operating conditions in paragraph 3.1.
- Paragraph 8.4. covers conformity of production tests when substantially different barometric pressure, humidity, temperature or rider mass prevent reaching awot,ref with the type approval gear.
- Why
- Technical services and type approval authorities had different interpretations of the Annex 7 ASEP tests.
- The GRBP report says that the IMMA proposals made the provisions against test defeating stronger and made conformity of production testing easier.
- A speed tolerance prevents small speed deviations from making test runs invalid.
Q1What changed38 changes
Devices, procedures or software used to pass the tests (para. 6.3.1.)
The motorcycle manufacturer must not use a device, procedure or software that meets two conditions. First, it modifies noise related functional parameters of the vehicle to pass the tests of this Regulation. Second, it causes higher noise emissions in typical on-road operation in the RD-ASEP control range of Annex 7 paragraph 2.5 than during testing. Before this supplement, the manufacturer could not intentionally alter, adjust or introduce a device or procedure only to fulfil the noise requirements. That rule applied to a device or procedure that is not operational during typical on-road operation.
Conformity of production when awot,ref cannot be reached (para. 8.4.)
New paragraph 8.4. applies when the reference acceleration awot,ref cannot be reached with the same gear in conformity of production as in type approval tests. The paragraph names the cause: substantially different barometric pressure, humidity, temperature or rider mass. In this case, the gear selection requirement of paragraph 1.3.3.3.1.3.1. of Annex 3 must prevail. The conformity of production tests can then use an acceleration different from awot,ref.
User selectable modes in the Annex 3 test (Annex 3, para. 1.3.3.1.3.)
New paragraph 1.3.3.1.3. of Annex 3 applies if the vehicle has user selectable software programs or modes. The test must then use a mode that does not restrict the power performance of the vehicle and that gives the highest Lwot(i). Manufacturer documentation goes to the technical service responsible for the approval tests. Based on this documentation, the technical service selects the program or mode to test. New measurements of Lwot(i) and nwot(i) under paragraph 2.6. of Annex 7 must now use the same user selectable drive mode as in type approval.
Speed tolerances and deceleration (Annex 7, paras. 2.5., 2.8. and 3.3.1.)
New paragraph 2.8. of Annex 7 gives a tolerance of +/- 5 km/h for tests according to paragraph 3.3. and point (b) of paragraph 3.2.2. The tolerance must respect the boundaries of the RD-ASEP control range defined in paragraph 2.5. Paragraph 2.8. also gives examples, such as a requested vBB’ of 100 km/h with a valid vBB’ of 95-100 km/h. Before this supplement, paragraph 3.3.1. gave a tolerance of +/- 5 km/h for the test speed vtest at line AA’. Paragraph 3.3.1. now says that a deceleration is present when vPP’ < vAA’ - 5 km/h, vBB’ < vAA’ - 5 km/h, or vBB’ < vPP’ - 5 km/h. The title of paragraph 2.5. is now “ASEP control range” instead of “RD-ASEP control range”.
Number of additional operating conditions (Annex 7, para. 3.1.)
For vehicles with manual transmissions, the total number of operating conditions to test according to paragraph 3.3. is the number of gears multiplied by 3. For vehicles with variable gear ratios or automatic transmission with non-lockable gear ratios, this total number is 6. In both cases, this total is reduced by the operating conditions used for the tests of paragraph 3.2 and for the determination of Lurb. A minimum of 3 operating conditions must be tested according to paragraph 3.3. Before this supplement, testing was restricted to the reference points and three additional operating conditions per gear. For vehicles with variable gear ratios or automatic transmission with non-lockable gear ratios, the limit was 6 conditions different from those used for Lurb.
Test conditions set by the technical service (Annex 7, paras. 3.3.1. and 3.3.2.)
The conditions of paragraph 3.3.2. must now be defined by the technical service responsible for conducting the approval tests. Before this supplement, the technical service could define them in agreement with the type approval authorities. For the throttle control position when the vehicle passes line AA’, the words “in agreement with the type approval authorities” are also removed. Manufacturer documentation is given to the technical service to help define these conditions, and the technical service can request pre-testing of the vehicle. Within the total number of additional operating conditions of paragraph 3.1, the vehicle may be tested in any available user selectable software program or mode. Before, the text named only programs or modes which affect the sound emissions of the vehicle.
RD-ASEP table in item 18 of Annex 1
The table in item 18 now names the reference points (a) and (b) instead of (i) and (ii). In rows 18.1.5.1. and 18.1.5.2. for the engine speeds nAA’ and nPP’, the unit is now (km/h) instead of (min-1). The text about the columns for the additional operating conditions now starts with “Note:” instead of “Footnote:”.
Q2Why it changed
- Proposed by
- Experts from the Informal Working Group on Real Driving - Additional Sound Emission Provisions (IWG RD-ASEP) for Annex 3 and Annex 7; experts from the International Motorcycle Manufacturer Association (IMMA) for paragraphs 6.3.1. and 8.4. and Annex 1
- Working party
- GRBP, 81st session (February 2025)
Reasons
IMMA saw that technical services and type approval authorities had different interpretations of the Annex 7 ASEP tests. They differed on how to test user selectable riding modes, how to find the number of additional operating conditions and which speed tolerances to apply. IWG RD-ASEP wants to make the original intent of the 05 series clear and to make sure that the ASEP tests are applied uniformly.
Sources (2)
“IMMA noticed that Technical Services and Type Approval Authorities had varying interpretations on how to test different user selectable riding modes, on how to determine the number of additional operating conditions”
“With this amendment proposal IWG RD-ASEP would like to clarify the original intent of the 05 series of amendments as well as to ensure uniform application of the ASEP tests.”
User selectable riding modes are becoming more available on motorcycles. The Lwot(i) value appears on the statutory plate of the manufacturer. It is also used to find the anchor point for the ASEP limit line in Annex 7.
Sources (2)
“With user selectable riding modes becoming more available on motorcycles, a new paragraph 1.3.3.1.3. is added in Annex 3”
“the Lwot(i) value will appear on the manufacturer’s statutory plate and will be used to determine the ‘anchor point’ for the ASEP limit line in Annex 7.”
Speed tolerances were already given for vAA’ in paragraph 3.3.1., but there were none for the reference test condition in point (b) of paragraph 3.2.2. For the determination of deceleration, a tolerance of -5 km/h is given. Such a tolerance prevents small speed deviations from making test runs invalid.
Sources (3)
“Such speed tolerances were already specified for the vAA’in paragraph 3.3.1. but were lacking for the reference test condition of paragraph 3.2.2.(b).”
“For the determination of deceleration in the context of RD-ASEP testing (paragraph 3.3.1) a tolerance of -5 km/h is specified.”
“Such tolerance avoids invalidating test runs from small speed deviations.”
Paragraph 6.3.1. is to make sure that the behaviour tested during approval represents how the vehicle behaves in real-world traffic. The new text adds software as one of the potential applications of concern. The GRBP report says that the IMMA proposals made the provisions against test defeating stronger.
Sources (3)
“Paragraph 6.3.1. is about ensuring that whatever is tested during the approval is representing how the vehicle will behave in real-world traffic.”
“The proposed text adding ‘software’ as one of the potential applications of concern.”
“introduced amendment proposals to the 04 and 05 series of amendments that strengthened provisions against test defeating”
For conformity of production, paragraph 8.2. asks for the same gear and pre-acceleration distance as in the original type approval test. Humidity and barometric pressure can change vehicle performance, and UN Regulation No. 41 does not consider them. In some cases, meteorological conditions and rider mass can stop the type approval gear from reaching awot,ref within ±10 percent in conformity of production tests.
Sources (4)
“Paragraph 8.2. asks for CoP sound levels (Lurban and Lwot) to be measured and processed according to the method described in Annex 3, with the same gear(s) and pre-acceleration distance(s) as used in the original type approval test.”
“Meteorological variables such as humidity and barometric pressure can result in variations of vehicle performance and are not considered by UN Regulation No. 41.”
“Under certain circumstances, changing the meteorological conditions and rider mass within the acceptable tolerances allowed by the Regulation, it may not be achievable to respect ±10 percent of the reference acceleration awot,ref”
“if the same gear is used in TA and CoP tests.”
Document trail
- 2024-12ProposalECE/TRANS/WP.29/GRBP/2025/4Proposal by IWG RD-ASEP on the Annex 7 ASEP tests
- 2024-12ProposalECE/TRANS/WP.29/GRBP/2025/7Proposal by IMMA on test defeating, conformity of production and the communication document
- —RevisedGRBP-81-03Changes by IWG RD-ASEP that GRBP adopted with the proposal
- —RevisedGRBP-81-29Changes by IMMA that GRBP adopted with the proposal
- —Working party adoptsECE/TRANS/WP.29/GRBP/79Session report, paras. 4 and 5
- 2025-04Sent to WP.29ECE/TRANS/WP.29/2025/70Text that GRBP sent to WP.29 and AC.1
- 2025-06WP.29 adoptsECE/TRANS/WP.29/1186Adopted at the 196th session (session report, para. 111)
- 2026-01-11In forceC.N.25.2026.TREATIES-XI.B.16.41UN depositary notification
Q3Who is affected
Vehicle manufacturer
- Review your devices, procedures and noise related software against the new text of paragraph 6.3.1.
- Be ready to give the technical service documentation on user selectable programs or modes (Annex 3, paragraph 1.3.3.1.3.).
- Plan conformity of production tests for the case of paragraph 8.4., when awot,ref cannot be reached with the same gear.
Component supplier
- Check the noise related software that you supply against the new text of paragraph 6.3.1.
Technical service / Approval authority
- If the vehicle has user selectable modes, select the Annex 3 test mode from the manufacturer documentation (paragraph 1.3.3.1.3.).
- Apply the tolerance of Annex 7, paragraph 2.8., to tests of paragraphs 3.3. and 3.2.2.(b), within the RD-ASEP control range.
- Count the additional operating conditions with the new rules of Annex 7, paragraph 3.1., including the minimum of 3.
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ⓘ This report gives advice only. It is not legal or type-approval advice.
More UN R41 change reports
- 06 series — Supplement 1
- 06 series — Base text
- 05 series — Supplement 5
- 05 series — Supplement 3
- 05 series — Supplement 2
- 05 series — Supplement 1
- 05 series — Base text
- 04 series — Supplement 13
- 04 series — Supplement 12
- 04 series — Supplement 11
- 04 series — Supplement 10
- 04 series — Supplement 9
- 04 series — Supplement 8
- 04 series — Supplement 7