Press-fit bottom bracket tools work by staying square. The moment the tool can tilt inside the shell, it stops pushing the bearing straight out and starts pushing it into the frame. The plastic ring on the Unior 1625/2BB90 is the part that prevents that, and because it is the softest component in the assembly, it is also the part that wears first. What this is The 1625.2/2BB90 is the genuine replacement plastic ring for the Unior 1625/2BB90 BB90 removal tool. It is a service part, sold on its own so a worn ring does not mean replacing the whole tool. When to replace it Replace the ring when it is visibly scored, deformed, or no longer holds the tool centred in the shell. A worn ring shows up as a tool that feels like it wants to cock over as pressure comes on; the ring is doing its job right up until it isn't, and the failure mode is the tool going crooked rather than the ring falling apart. In a high-volume shop that services a lot of Trek frames, this is a consumable. In a home workshop it may well outlast the bikes. Why the ring is plastic Because the alternative is metal, and metal against a bearing bore leaves marks in the frame. The ring is deliberately the sacrificial component in the assembly: it is softer than both the tool and the frame, so wear lands on the cheap replaceable part rather than on the shell of somebody's frame. That is a design decision, not a cost saving. Compatibility Fits the Unior 1625/2BB90 BB90 removal tool. It is not a universal press-fit tool part; check your tool's part number before ordering. Built in Zreče, Slovenia Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. Stocking individual service parts for a tool this specific is the part of the catalog that does not pay for itself directly; it exists so a workshop tool stays a repairable object rather than a disposable one. Pro tip from our mechanics Check the ring before the job, not during it. A press-fit removal is one of the few procedures where discovering a worn tool halfway through leaves you with a partially extracted bearing and no good options. Ten seconds of inspection up front. Our press-fit guidance and broader workshop setup notes: How to set up a professional bike workshop →
