I am working on understanding this document for an n55 trike frame build ...


Particularly this line:

M6 SELFLOCKING NUTS, stainless (DIN985) - ca. 150 pieces (TWOSEATER: 200 pieces)

After some googling I found out that M6 refers to Metric and 6 refers to 6mm.

Self locking means the nuts are better at handling vibrations so they do not become loose.

However the DIN985 I can not determine.

Google did not appear to pull up anything useful: search

What does this refer to?

  • 3
    I'm voting to close this question as off-topic. Fastener standards are not specific to bicycles. – Argenti Apparatus Jan 11 '20 at 11:50

DIN stands for ‘Deutsches Institut für Normung’ which means ‘German Institute of Standardization’. DIN develops norms and standards as a service to industry, to the state and to society as a whole. It is a registered non profit organization which has been based in Berlin since 1917. It consists of nearly 1,700 members who include individual companies, associations, public authorities, and other organizations from industry, commerce, the trades and research. DIN members support standardization through membership fees and play an active part in the decision making process.

DIN 985 defines the parameters for self locking nuts or "Prevailing torque type hexagon thin nuts with nonmetallic insert".

There are a variety of standards for nuts, bolts etc. that have been created to assure a level of quality for a given task. The standard will designate dimensions, chemical composition and mechanical properties. For a given standard (933) there are property classes (4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9 and 12.9) with different chemical compositions and mechanical properties. The N55 specification does not indicate which property class is required. Generally, the higher the property class number the "stronger" the bolt.

If your hardware provider is familiar with a different standard there are cross reference tables available on line that allow you to find equivalents in whatever standard is available to you (EN, ISO, ANSI etc.). I'd be comfortable with even a property class of 4.8 for this application. The key is to get something that has been rated as opposed to something made by a company that does not even bother to rate the hardware.

  • As an aside, you also see DIN used in reference to fonts, which is where I first heard it. They've specified several fonts, some used for German highway signs, some quite attractive in an austere way and used on cover art for electronic dance music from the 1990s. – compton Jan 12 '20 at 4:50
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    @compton Yes, DIN has standards for seemingly everything right down to paper sizes din.de – David D Jan 12 '20 at 14:28
  • Thanks, following up DIN 985 ( in n55 spec. ) is just a standard created by this institute. Why did you bring up DIN 933 ? – jennifer Jan 25 '20 at 17:20

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