Birdy AXS: Introduction to Birdy City (Suspension and Brake System)

Here is the second part of the Birdy City folding bike introduction. In the first part, the drivetrain was introduced, with all components in the stock condition. In this post, the stock suspension and brake system will be shown.

View of the stock Birdy City from the non-drive side.

Front suspension fork, with the unique Birdy suspension geometry and design.

Stock suspension is very simple, with just a coil spring, a rubber block and a foam insert.

Coil spring hooks to the latch, so that it can be disengaged for folding. More details on this later when I dismantle the suspension fork.

Fork is attached to the head tube through an inverted stem design. The steerer tube is part of the handlepost, while the fork clamps onto the steerer tube like a normal Aheadset stem. Shown here is the "top" cap for headset bearing pre-load, located at the bottom of the fork crown.

Due to folding requirements, the front brake caliper is located on the drive side instead of the usual non-drive side. This presents some challenges unique to this Birdy bike design.

To make the folding more compact, the front hub flanges are offset inwards on both sides. Brake rotor position is also offset inwards. Hub width is still the standard 100 mm OLD.

Note the extra long hub axle section due to the inward offset hub flanges.

Integrated headset design, wide handlepost clamp section. Large hole on the main frame for internal cable routing.

Rear shifting cable bridges across from the "down tube" to the rear triangle, through the use of a metal noodle (similar to a V brake noodle) to minimize damage during folding.

Different aluminium grades used for frame tubing and main frame, although I think the frame tubing is actually a part of the main frame???

The rear brake cable also bridges across from the "down tube" to the rear triangle, but secured differently from the rear shifting cable.

Rear suspension block is just a rubber block like the Brompton. The latch shown at the bottom of the picture hooks onto a metal pin on the seat tube, to prevent the rear triangle from dropping down when the bike is lifted.

Pivot for the rear triangle is basically a solid pin that is press-fitted into the frame, while both sides of the rear triangle clamps onto the pin.

Rear brake cable bends sharply when it exits the rear triangle. Very bad for cable efficiency.

Avid BB5 mechanical disc brakes, and lots of spacers used to adjust the brake caliper position. Quick release rear axle as well. Rear rack and mudguard mounts are available.

Although the front hub design and front brake caliper placement is unique to Birdy, luckily it uses a standard brake caliper and rotor. This enables easier modifications and upgrades without proprietary brake components. The unique front hub with inward offset flanges can be a problem though, as there are only a few brands that make these Birdy specific front hubs.