Bottom Bracket Tap Cutters BSA

A BSA BB tap is a serviceable item. The cutting teeth are what chase the thread, and after enough cuts they lose the sharp edge that lets them feed through a paint-fresh shell cleanly. The 1697.1 BSA cutters are the replacement pair, sized to the 1697 tap holder, so a shop that's wearing cutters on a busy bench can swap them in without buying a new complete tap set.

What this piece does

The 1697.1 BSA tap cutter set is the BSA-thread cutting end of the 1697 BB tap system. The pair comes in matched right-hand and left-hand cuts (R for non-drive, L for drive), with the same 1.37″ × 24 TPI BSA pitch as the original 1697 cutters. Mount them into the BSA tap holders, put the holders on the modular handles, and the system is ready for the next shell.

Use cases

• Replacement. When the original 1697 cutters are dull beyond resharpening. The cutting teeth take the working load; once they round off, swarf comes off as chunks instead of ribbons, and that's the cue to swap.
• Configurable kit. If you already own a 1698 Italian tap system and need BSA capability, buying the BSA cutters and the BSA tap holders is enough to chase BSA threads with the same handles you already have. The modular pattern is designed for this kind of bench expansion.

Compatibility

• BSA-threaded BB shells (1.37″ × 24 TPI)
• Fits the BSA Bottom Bracket Tap Holder 1697.2/4
• Drives through the modular frame-prep handles 1695.1/4BI

Specs

• Thread: 1.3/8 × 24 TPI (BSA); thickness 18 mm; pair weight 117 g
• Pair: one right-hand cutter (non-drive), one left-hand cutter (drive)
• Made in Slovenia by Unior from premium plus carbon steel, trivalent chrome plated; lifetime warranty

Includes: Right-hand BSA tap cutter, left-hand BSA tap cutter. Tap holders, the 1697.4 guide, and handles sold separately.

Made in Slovenia, since 1919

Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. The taps themselves are the working face of the BB-prep system; everything else (holders, handles, frame) is structure. Selling them as a replaceable pair is the same logic that drives the rest of the modular frame-prep catalog.

Pro tip from our mechanics

Paint film is the first thing a fresh cutter pair eats through, and it's also the thing that takes a real bite out of cutting-edge life. On a heavily-painted shell, the first quarter-turn pass passes through paint, not metal; the cutter edge sees abrasive paint film, not the cleaner cut of bare thread. Keeping a worn-but-not-retired pair around for that first paint-clearing pass extends the life of the sharper replacement pair.

The mount-orientation safety check before each install: each tap is engraved 1697 R or 1697 L. R is the right-hand (non-drive) tap; L is the left-hand (drive) tap. A drive-side (left-hand thread) cutter mounted on the non-drive holder cuts in the wrong direction; it either won't bite or galls the shell threads. When a cutter starts producing chunky swarf instead of ribbons, it's done; sharpening BB tap cutters isn't a workshop operation, so order the replacement pair and rotate.

The BSA-shell walk-through covers paint film, swarf morphology, and the dual-tap simultaneous-drive setup that keeps the cutters parallel through the shell: Frame prep: threaded bottom bracket shells →

FAQ

Does this pair cut new BSA threads or only clean up existing ones? Unior describes the 1697 system as the tool for fixing bottom-bracket threads on the frame and for removing excess paint or dirt from those threads. Article 1697.1 is the left-and-right cutting pair that does that work. A chase will not rebuild a stripped shell; that repair is a thread insert or frame work.

Which bottom-bracket shells do these taps fit? BSA (English) threaded shells only: 1.3/8 × 24 TPI, left-hand thread on the drive side and right-hand thread on the non-drive side. Italian-threaded shells (36 mm × 24 TPI) take the 1698.1 taps. Press-fit shells are a different standard and need different tooling.

What else do I need besides this pair to chase a shell? These are the two taps only. They mount in the 1697.2/4 BSA adapters and are driven by Unior's 1695/4BI magnetic handle. The 1697.4 guide joins both taps through the shell. Adapters, guide, and handles are sold separately. The 1697.3 set bundles this pair with two adapters and the guide; 1697-US is the version that also ships the handles.

How do I tell the left tap from the right? Each tap is engraved 1697 L or 1697 R on the face. L is the left-hand (drive-side) tap; R is the right-hand (non-drive) tap. Mounting them on the opposite holders will not feed the thread.