The stock Birdy rear unit is a block. You can leave it as a block, or you can replace it with a real suspension unit. A real unit is a compound structure by necessity: not only a block, not only a spring, because a bump is not only one variable.

Measured as a block, the JuinTECH unit is not cheap. Measured as a suspension unit, it is what the structure should have been all along.

The spring responds to how far you compress and provides support. The viscous damping medium responds to how fast, turning the energy of the bump into heat instead of returning it to you as a bounce. The urethane element cushions the end of the stroke. The vent lets the displaced air out so it never becomes an invisible air spring.

Long travel favours piston-and-valve dampers. At 10 mm, we chose another path: shear damping through a high-viscosity medium, with no sealed high-pressure chamber and no seal to fail. It is a structure that can be serviced and replenished, not consumed.

Many aftermarket rear units are too bulky and collide with the rear rack when the bike is folded. The JuinTECH unit is 32 mm in diameter and 42 mm tall, close to the stock dimensions, so folding stays clean. If you run a non-stock rack, check that clearance before ordering.

One thing to know before installing: a new unit is slightly longer than the stock block. That is the spring pre-load, the same reason a car sits high on new shocks and settles after a few drives. Compress the unit to fit, slide the stock retaining clip to the right position, and tighten.

Every PRECISO part is anodised under strict colour control, so the front suspension, rear suspension, kickstand, hinge lever, stem cap, headset and clamps on your Birdy all land on the same shade. No mismatched parts, no compromise. Five colours: Black, Silver, Red, Gold, Grey.

CNC-machined from 6061 aluminium, 100% designed and made in Taiwan. JuinTECH is an OE parts supplier to Pacific Cycles; PRECISO parts fit every Birdy produced from July 2015 onward.