Taps T47

T47 is the newest threaded BB standard in wide use. Chris King helped develop the spec: a 47 mm thread diameter, 1.0 mm pitch, right-hand on the non-drive side and left-hand on the drive side. Trek adopted it as T47i (internal bearing) on a generation of high-end road and gravel bikes, and an asymmetric variant, T47a, uses a different cup arrangement again. The standard solves two problems at once: wider shell for larger spindle diameters, and threaded engagement so it can't develop the creak of a press-fit shell. The Taps T47 chase the M47×1 threads in those shells the same way the 1697 and 1698 chase BSA and Italian threads in their respective shells.

What the tool does

The taps are a matched pair: a right-hand tap for the non-drive side, a left-hand tap for the drive side. Run them through the shell threads after the frame comes back from paint, after a frame swap, or any time you want to confirm the threads are clean enough to torque a cup into without binding. The tap doesn't cut new threads in unthreaded material; it chases existing threads, removing paint film, anodize buildup, and minor thread damage.

The taps are compatible with Unior's existing BB tap holders: the 1697 BSA-pattern handle and the 1698 Italian-pattern handle. Same modular frame-prep series as the BB Facing Tool 1699 and the Head Tube Reamer 1694; one handle drives the whole kit.

Compatibility

• T47 shells (M47 × 1.0 mm thread)
• All current T47 metal shells (Trek T47i, T47a, Chris King T47 cups)
• Carbon T47 shells with metal threaded inserts
• Pair with Unior tap holders 1697 (BSA-pattern handle) and 1698 (Italian-pattern handle)

Specs

• Thread: M47 × 1 (LH / RH); article 1695.5; pair weight 267 g
• Pair: one right-hand tap (non-drive), one left-hand tap (drive)
• Material: durable tool steel for long service life
• Compatible with Unior 1697 and 1698 bottom-bracket tapping tools
• Made in Slovenia by Unior

Includes: Right-hand tap, left-hand tap. Tap holder (1697 or 1698) 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. T47 is a younger standard than most of the BB shells the Unior catalog services; the T47 taps are the catalog's response to Chris King's standard becoming a real production fitment. The shared-handle decision means a shop adding T47 service to its bench doesn't add another full toolkit; it adds two taps.

Pro tip from our mechanics

Always use cutting oil. The thread is finer than BSA's 24 TPI, and a dry tap on T47 threads will gall and lift small chips into the shell, which then bind the cup install. A drop of cutting oil on each tap before it enters the shell is the cheap insurance.

If you're chasing T47 threads on a frame coming back from paint, run the tap until the thread cuts cleanly; meaning the swarf coming off is a smooth ribbon, not chunks. Stop, reverse a quarter-turn to break the chip, then continue. Force always produces worse results than patience here.

The BSA-shell walk-through (chasing threads, facing the shell, feed control) is the T47 cousin in our Tech Tips library; same procedure, different thread spec: Frame prep: threaded bottom bracket shells →

FAQ

Does article 1695.5 cut new T47 threads or only restore existing ones? Unior designed these taps for chasing and restoring existing T47 threads, and for cleaning and restoring existing threads in T47 bottom-bracket shells. A chase will not cut a new thread in unthreaded material and will not rebuild a stripped shell.

Which bottom-bracket shells do the T47 taps fit? All T47 metal bottom-bracket shells. The pair is precision-machined M47 × 1, with left-hand and right-hand taps included. Official table: M47x1 - LH / RH (T47). BSA shells take the 1697.1 taps; Italian-threaded shells take the 1698.1 taps.

What else do I need besides this pair to chase a T47 shell? These are the two taps only. Unior lists them as compatible with current and previous generations of Unior bottom-bracket tapping tools 1697 and 1698, which are sold separately. Always use cutting oil.

How are the left-hand and right-hand T47 taps marked? Each tap is engraved M47x1-LH or M47x1-RH, plus T47 and article 1695.5. Official Unior copy does not assign those marks to the drive or non-drive side of the bike; match the engraving to the cup thread you are chasing.