Adjustable screw for clamp 1693.1 and 1693.1S

The Adjustable Screw 1693.21 is the threaded handle and screw shaft that dials in the jaw pressure on Unior's cam-style clamp heads: the 1693.1 and 1693.1S, in the older square-style jaw geometry with the 90 mm or 70 mm jaw height. Two cases bring shops to this part: a screw that's threaded out of tolerance after years of bike-to-bike pressure setting, and a clamp where the handle has been overtorqued and the screw has bent.

The cam-style clamp's pressure adjustment is a wear part by design. The lever closes the jaws against the pressure dialed in by the adjustable screw; over thousands of clamping cycles, the screw threads see the load and the wear shows up as a screw that doesn't seat at the same pressure for a given handle position. The 1693.21 replacement screw restores the clamp's pressure-setting precision without requiring a full clamp head replacement.

Compatibility

The 1693.21 fits the older square-style jaw clamp geometry on these clamp heads:

• Pro Repair Clamp 1693.1S (manually adjustable cam-style)
• Earlier 1693.1 cam-style clamps with 70 mm or 90 mm jaw height

If your clamp is the round-jaw Master Shop Clamp (1693.1M) or the quick-release Pro Shop Clamp (1693.1Q), this screw is not the right part. The Master Shop and Pro Shop use different pressure-setting mechanisms; the 1693.1Q has its own rebuild kit (1693.1Q-SP.1), and the 1693.1M's clamp pressure is dialed via a different threaded interface.

Specs

• Article number: 1693.21
• Compatibility: Unior cam-style clamp heads 1693.1 and 1693.1S with old square-style jaws (70 mm or 90 mm jaw height)
• Function: adjustable pressure-setting screw for cam-style clamp mechanism

Includes: replacement adjustable screw with handle.

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill teams. The 1693.21 is a small part for a precise problem: the cam-clamp's pressure setting drifts over years of thumb-and-handle use, and the screw is the part that carries that drift. Replace the screw, the pressure precision comes back; the rest of the clamp stays in service.

Pro tip from our mechanics

Before you order the 1693.21, confirm your clamp's jaw geometry. The older square jaws are flat-faced and 70 mm or 90 mm tall; the newer round jaws (Master Shop and Pro Shop) are visibly cylindrical and shorter (50 mm to 70 mm). If your clamp has round jaws, the 1693.21 is the wrong part. For shops running multiple stand vintages, this is one of the small SKU-fitment calls that's worth getting right the first time. Replacing the screw on a working stand is one thing; upgrading the whole clamp head is another. The buying guide covers when each path makes sense: How to choose a bike repair stand →