Headset bearing dimensions vary by bike — there's no universal answer. Your username suggests a Turbo Levo, so I'll start there, but tell me which year and I can be precise.
Specialized Turbo Levo
•
Levo Gen 4 (2024+) upper bearing: 41.8 x 30.5 x 7mm, 45°/45°
• Older Levo/Kenevo bearings are available as a Specialized Headset Bearing Kit (Upper/Lower CG) — sold on eBay and through dealers
• 1.5" → 1.8" lower conversion uses Specialized part GPBHS454556865: 56.8mm OD x 47.8mm ID x 6.5mm, 45° angular contact
Common eMTB headset bearing sizes for reference
•
42 x 52 x 7mm, 45°/45° — the most common "standard" lower bearing. Found on plenty of integrated tapered headsets (e.g. LCE930 frames per
@JerryXC). Stock quality is often dire — stainless replacements are worth the small premium.
•
40 x 52 x 7mm, 45°/45° — Amflow, Cube Stereo Hybrid 160 (per
@BeBiker), Orbea Rise M20 2021 (per
@GunnarNyb). The Rise uses the Kinetic MH-P16 —
@GunnarNyb found them on AliExpress for around $3 each versus painful Norwegian prices.
•
IS41/52 — Bosch Vala MY25/MY26 (per
@pursuitofnow), 2022 Orbea Rise H30 Acros headset (IS42 upper, IS52 lower)
•
FSA MR127 upper / MR229 lower (61.9 x 8 x 50mm) — Specialized Kenevo SL/Relay, 2023 Giant Reign E (per
@parkp81, with 36°/45° angles)
•
Kinetic MH-P16K — Merida eOneSixty/E160 Limited Aluminium top and bottom (per
@RoJo)
How to find yours
1. Check the manufacturer's tech sheet — Orbea, Specialized, Trek and Giant all publish bearing specs in their owner's paperwork
2. Pull the existing bearing and measure: OD x ID x height, plus the angle stamped on the race (usually 45°/45° or 36°/45°)
3. Match the
IS code if integrated — IS42 = 42mm bearing seat, IS52 = 52mm seat
Stainless or black oxide replacements (Enduro Bearings, Cane Creek, Acros) outlast OEM by a wide margin, especially with the cable-through-headset designs that funnel water and grit straight onto the lower bearing.
Tell me the bike and year and I'll nail down the exact part numbers.