Birdy AXS: Stock Birdy Bike Ride Before Modifications

Now that I have studied the stock Birdy City in more detail, it is time to go for some test rides, to see how the stock setup performs. This will give a baseline feel before I disassemble and modify the Birdy folding bike.

During the test rides, the main areas that I will pay attention to would be the shifting performance, braking performance, rolling resistance, and suspension feel. Later on, after the bike has been upgraded, I will compare and see how much or little these areas have changed.

Before even riding, I have to adjust the saddle and seat post. As shown in the first post, the default seat post setting has a rearward offset, which means that the saddle position is rather far back. This is a problem for me as I need a zero offset seatpost in order to position my knee properly over the pedal spindle.

As I have previously done bike fitting at LOUE Bicycles, I am able to use the same setup to adjust the saddle position and height on the Birdy for the optimum riding posture. With a rearward offset seat post, it is not possible.

Luckily, this Birdy seat post is cleverly designed such that the saddle rail clamp can be reversed. Basically just rotate the seat post 180 degrees, then slide the clamp to compensate. This effectively gives the seat post a zero/forward offset, which is what I needed.

Birdy stock seat post rotated 180 degrees, with the saddle rail clamp adjusted to give a zero/forward offset. Pardon the messy workbench behind.

Transferred the PRO Stealth Off-Road saddle from the Fnhon DB12 over to this Birdy. This will be the saddle and seat post setup after modifications, as I don't plan to change the seat post.

Great weather at the newly restored Bukit Timah Railway Station!

I chose to ride there as there are gravel tracks along the Green Corridor, which makes it ideal for testing the suspension of the Birdy.

Riding all around the Bukit Timah area on the stock Birdy City.

Even checked out the newly opened Rifle Range Nature Park! Can't ride inside, only took a peek from outside.

A bit of mud splashes on the first test ride, from riding along the Green Corridor.

I installed the PD-A530 SPD/Flat pedals on the Birdy, as I didn't want to use the stock pedals.

After a few test rides, here is my feedback on the stock setup of the Birdy City.

Shifting Performance: Sora 1x9 speed drivetrain shifts well and works reliably, although I am not quite used to mechanical shifting as literally all my other bikes are using electronic shifting. Components are well adjusted by the bike shop mechanics.

Braking Performance: Avid BB5 mechanical disc brakes work well with no noise. Sora brake levers operate smoothly and comfortably. Brake pad clearance and all cable lengths are good as well.

Rolling Resistance: Decently low, given the relatively wide tires and basic wheelset. Definitely not as smooth as high end wheelsets with nice hubs, but correct spec at this price point.

Suspension performance: Works well on moderately bumpy terrain like broken or rough pavement found along the paved stretches of the Green Corridor. However, the suspension gets overwhelmed when riding over true gravel stretches with embedded rocks and wooden planks. Due to the very basic suspension design (coil spring at front, rubber block at rear) with short travel and no damping, the suspension does not absorb bigger bumps.

I tried to ride the Birdy like a gravel bike, by riding fast and hard over the gravel stretches, but it gets super bumpy when used this way. Although the Birdy is technically a full suspension bike, it is very limited in terms of suspension performance, and I need to temper my expectations of it. In other words, don't expect the Birdy to perform like a gravel bike or MTB on rough terrain. Think of it like a mini velo with ride-dampening suspension, something like an Alex Moulton bike.

However, the Birdy is still better over rough terrain compared to the bifold Fnhon DB12, which has no suspension at all. On the Birdy, I don't have to worry about overstressing the folding joints when riding over short stretches of rough terrain, or dropping off small kerbs.

One last thing to do before I disassemble the stock Birdy City is to check the stock full bike weight. This will be compared to the final weight after all the modifications are completed.

 

Stock Birdy City is 10.84 kg without pedals. This is with the stock Birdy saddle.

Stock pedals are about 260 grams, which is actually pretty lightweight.

Stock Birdy City has a weight of 11.1 kg including pedals, and about 10.84 kg without pedals. Note that this is with the lighter fixed height (non-telescopic) Birdy handlepost, instead of the heavier telescopic version. Kickstand is not included.

Stock full bike is pretty heavy, but still lighter than the Brompton M6R which has a stock weight of 12.3 kg. I hope this means that there is much room to reduce weight by changing the components, instead of the alternative explanation, which is a heavy frameset.

A few more measurements before disassembling the stock Birdy City.

Stock tire width is about 36.7 mm. It is a good width if you want comfort and light off-road riding, but too wide if you are looking for speed.

Actual tire diameter is 440 mm with the stock tire and 18" 355 rims.

These tires look like Schwalbe Marathon with the tread pattern and reflective strip, but is actually a lookalike made by CST.

Clearance between the tire and the Sora rear derailleur cage. For small wheels, cage length and tire width needs to be considered to avoid interference.

Clearance is about 9 mm, which is no problem at all. To be safe, at least 4 mm of clearance is needed at nominal conditions.

With that, the study of the stock Birdy City is complete. Next step is to disassemble and study the Birdy frameset, before introducing the new components and assembling the bike.