OK, folks, to me an "ERD" is the acronym for "Entity Relationship Diagram", which is a description of a database. What are you referring to with "ERD"?
Make me smarter, please. I need all the help I can get.
Since you asked so nicely;
ERD Entity Relationship Diagram
ERD Ethical and Religious Directives (Catholic Health Care Services)
ERD Emergency Repair Disk
ERD Episcopal Relief and Development
ERD Economic Relations Division (Bangladesh)
ERD Event-Related Desynchronization
ERD Extended Reach Drilling (oil industry)
ERD Emergency Response Division
ERD Elastic Recoil Detection
ERD Environmental Restoration Division
ERD Energy Recovery Device
ERD Explosives Regulatory Division
ERD Eligible Rollover Distribution
ERD Early Return of Dependents
ERD effective rim diameter (cycles)ERD Ecosystems Research Division (US EPA)
ERD Employee Relations Division
ERD Esophageal Reflux Disease
ERD Earthquake Resistant Design
ERD Early Random Drop
ERD Expected Reinsurer Deficit (CAS Risk Transfer Metric)
eRD E-Referencedesk
ERD Estimated Release Date
ERD Early Release Date (prision)
ERD Emergency Reserve Decoration (UK)
ERD Environmental Radiation Data
ERD Early Renal Damage
ERD Electronic Restraint Device
ERD Equal-Cost-Route Descriptor (Cisco)
ERD Equivalent Residual Dose
ERD Enterprise Relational Database
ERD Equipment Readiness Date
ERD Experimental Research Design
ERD Employment Relations Divisions (Montana)
ERD External Reuse Density
ERD External Requirements Document
ERD Estimating Requirements Document (mini Cost Analysis Requirements Document)
ERD Engineering Review Diagram
Erd Total Residential Energy Demand (Carolina Environmental Program)
ERD Expected Recovery Date (medical terminology)
ERD Envelope Recipient Domain (email)
ERD Exchange Rate Difference (finance)
ERD Électricité de France Réseaux de Distribution (French)
ERD External Relations Department (various organizations)
It could also be used to describe the typical British weather that I've had to put up with this "Summer" - Enormous Rain Drops!
Visual proof attached below
(taken on 5th August!!).
Anyway, this should help to clarify the intended meaning:
Effective Rim Diameter.
This is the rim diameter measured at the nipple seats in the spoke holes, plus the thickness of the two nipple heads.
The E.R.D. is needed for calculating the correct spoke length.
I tried to determine the ERD on a built up wheel and I reckon it is somewhere around 518mm on the 26" GM rim that I measured.
(The inside diameter is approximately 508mm and the 13mm long nipples only have ~8mm protruding from the inside of the rim.)The factory fitted spokes are 110mm long when measured from the inside of the elbow:
Alan