HOLLOWTECH II vs BB86 vs T47: Bottom Bracket Standards Explained

Introduction

Bottom bracket standards cause more confusion than any other bike part. Here's what actually distinguishes them and why your frame's BB matters more than the brand you choose.

Threaded BB Types

BSA/English BB (68mm or 73mm): The most common threaded standard. Easy to install, widely supported, creaks if not torqued properly.

Italian BB: 70mm shell, opposite-thread left side. Rare now, mostly on carbon or titanium frames. Mechanic knowledge limited.

T47: threaded BB evolved — wider shell (46-47mm), no bearing preload adjustment needed, used by Specialized, Trek, Cervelo. Quality mechanic-friendly.

Press-Fit BB Types

BB86/B86: Shimano press-fit, 86mm shell width. Common on Shimano-equipped frames. Creaks if bearing oxidation occurs. Requires proper tolerance maintenance.

BB90/B90: Trek's press-fit standard. Similar to BB86 but frame-specific. Trek BB90 frames use proprietary bearings.

PF30: 46mm bearing ID, wider shell. Cannondale pioneered this. Adapter options available for BSA conversions.

BB386Evo: SRAM's wide-shell press-fit (86.5mm). Accepts GXP or BB386Evo spindles. Versatile but frame modification may be needed.

Creaking — The #1 BB Problem

Before blaming the standard, eliminate the usual suspects: torque spec compliance (35-50 Nm for most), proper grease on threads, no bearing oxidation, no frame prep issues. A creaking BB is usually a torque problem, not a standard problem.

Which Lasts Longest?

In comparable conditions: BSA/English threaded > T47 > BB90 > BB86 > PF30 > BB386Evo for bearing longevity. Press-fit bearings suffer more from moisture ingress because the bearing sits in the frame directly — no shell seal.

Our Take

If building new: BSA/T47 for simplicity and longevity. If buying a complete bike: whatever the frame accepts, just torque properly and maintain bearing surfaces.