Clients still ask on walkthroughs why task chairs almost always ride on five-star bases; trivia: BIFMA stability testing in the late ’70s nudged manufacturers that way because five casters cut tip incidents versus four. Are you seeing designers push back to four-star looks in 2025, and if so, how are risk teams and insurers responding?
Tried a four-star brief in early 2025 and, , the carrier shut it down at the BIFMA stability review. > casters cut tip incidents versus four. Are you seeing designers push back to four-star — yes, we still see the push, but we get sign-off by using a five-star undercarriage with a shroud that reads four, upsizing to 65 mm casters, lowering the cylinder, and sending a 30-sec tip-test clip to risk. Anyone cleared a true four-star on carpet without counterweights, @Jamal?
On our last spec, underwriting signed off after we bumped the base diameter to 27 inches on the cut sheet; once the radius hit that, the BIFMA stability review stopped flagging it. It does steal about 2 inches of under-desk clearance, so facilities grumble. Anyone else gotten @risk comfortable at 26 inches with self-braking casters?
We got @risk comfortable by spec’ing a short-stroke gas lift to cap max seat height at about 20.5 in; keeping the center of mass lower made a 26 in base with self-braking casters pass without drama. Small caveat: tall users complained, so we paired those rooms with stool-height variants — anyone else split the spec like that?
we’ve kept the look by tucking a 1–2 kg steel ballast plate under the column, which drops the center of mass so a sleeker base still clears the tip tests from that late ’70s shift; it’s added roughly $6–$8 per chair for us. If @Liam wants chapter/verse, the overview’s here: https://www.bifma.org/page/standards. Have you gotten sign-off using hidden ballast instead of upsizing the radius or limiting stroke?
For clients chasing a sleeker base, we’ve cleared BIFMA X5.1’s ‘rearward stability’ by limiting recline to about 12–14 degrees and swapping to 50 mm soft‑tread casters on hard floors — like putting the training wheels a notch lower. Insurers have been fine with that in task areas but still twitchy on drafting heights; refs here: https://www.bifma.org/page/standards. Are your risk folks carving out different rules for conference chairs versus heads‑down seating?
And we got a four-star through risk in conference rooms by locking the seat slide at mid and bumping the tilt spring preload, plus a tamper clip to cap seat height at 18.5 in — kept the center of mass inside the base in our shop checks. Caveat: tall users leaning hard forward still flirt with the edge, so we stuck with five-star at workstations. @clopez08 did your team accept seat-slide locks?
Our underwriter only okayed a four-star after we pushed the base radius to about 350 mm and used light auto‑braking casters that engage past a few degrees, which kills the slow roll‑away that turns a lean into a tip. Not pretty, but physics is a grumpy PM. Anyone getting sign‑off by specifying a minimum footprint instead of clipping recline?
We’ve kept insurers calm on a 4‑star prototype by killing ‘foot‑perching’ leverage — slight negative draft on the leg tops and a tiny rear skid that only touches down past about 15° as a passive anti‑tip. Curious if you or @bperez99 have tried the five‑to‑four visual trick (a shroud over a compact 5‑star), or do risk teams call that ‘optics without physics’?