[The student surpasses the teacher] Popular mod-kit from BIKEfun RAD. Stirling damper second generation is on the market! STIRLING DAMPER II

“Never dare to admit perfection, and arrogantly draw a finish line" BIKEfun has been motivated by this value on developing and designing products.  As the forefront of development and innovation, we design and provide the best products. We also listen to the opinions of the Brompton owners during the actual modification process and thought about how to solve the problems that customers may have. How should we make BIKEfun's products stand on the international stage in the name of Taiwan?


Early since 2012, BIKEfun launched the first Brompton STIRLING DAMPER with the “industrial steam era” Stirling engine as a visual element, giving the modified Brompton the nostalgic mechanical style.


During this six-year period, the STIRLING DAMPER was widely welcomed by Brompton owners.


This motivated BIKEfun to launch the latest revision of the STIRLING DAMPER II at this time in 2018. This revision is not just a difference in appearance. We have added a new structure to fix the clearance between the rear triangle and the main frame when the bike is unfolded. Over the years, we have interacted with many owners when modifying the brompton and we’ve been asked:


Is the stock body clearance discrepancy normal? Can't it be solved?

If you can accept all the stock problems and imperfection happily, then all the flaws can indeed be called "normal." But we know...

"Your expectations for Brompton are not just that!" 


So, we added a small body to the second-generation Stirling Damper which can be adjusted by simple way.

Then it can turn a small imperfection into a perfect Brompton!


In the video above, is the BIKEfun RAD “Color” damper prototype during its test stage.


The final product is the one officially released at 2018.09.27 BIKEfun RAD. STIRLING DAMPER II

Currently BIKEfun offers five colors for owners to choose from. 

Color: Blue / Black / Copper / Nickel / Red 

Price: 2,000 NTD


Nickel color anodizing was a challenge! In order to get the color as similar to the finish of the Brompton “nickel-plated” version. BIKEfun spent a lot of time calibrating the color.


This result is not bad, right? This is not pure silver! This color is also very suitable for brompton with other colors, and it has excellent texture.


Copper gold add a retro style on the bike.  You definitely need a brown saddle from Brooks to make the perfect combination. 




At BIKEfun we also continued to challenge ourselves during the whole process. With the new structure and design, the weight of the damper is greatly reduced. The whole set weighs only 110g!

This weight is not just from the damper body. It also includes the weight of the new front and rear fixed structures. And they are all newly designed as the stock parts are no longer used for installation. For the damper spindle screw, we used 6/4 titanium alloy. At the end of the spindle screw, we used an anti-loose nut. With the spindle screw and the anti-loose nut combined, not only does it not hurt the spindle screw thread but also increases safety.


As installed on the bike:


When paired with the BIKEfun RAD. seat post clamp, you will have the same color scheme! Of course, not every bike must be the same color, just go with your creativity, and create your own style!


When designing the product, BIKEfun hopes that the shape of the damper can avoid damage when the owners fold and pull up the bike frame and causes the damper to scrape the ground. These should be taken into consideration!


Unless you lift the bike over 30 degrees or the road condition is poor, it might be possible to cause the STIRLING DAMPER II to scrape with the ground! In case it really hit the floor, the black industrial plastic in front will protect the body initially. It is not easy to scratch the aluminum shell! BIKEfun also guarantees that the industrial plastic repair parts in front will be sold separately at a reasonable price in the future, so that you don't have to change the whole set. We know that you want to keep the whole bike beautiful and stunning.


 However, in addition to color, weight, and style... there is one thing! The most! The most! The most important thing that many Brompton owners are negligent when they modify the shock absorbers is:


"Don't forget the reason why the dampers are called dampers?"



Dampers are designed to absorb bumps and increase comfort while riding! You should not only choose the dampers by weight.


For many years, BIKEfun has always insisted on the use of two different materials for the elastic material on the dampers. In such a short stroke, the two most suitable materials are: spring and superior glue. And we use these two materials at the same time! Through our experiments, this is the only option that achieves the best balance between kinetic energy loss and damp absorption performance.


The film of the damper in action:

In general, the reason why other brands use similar elastomers for similar dampers, is mainly to hold the spring in place or increase the stiffness. However, the purpose of BIKEfun for using superior elastomer is different. We use it as a damper. In the development process, from the thickness to the hardness are carefully formulated! Also, we repeatedly road tested and listened to the valuable input from "seasoned" Brompton riders. With all the efforts we completed this important small part with efficiency and comfort. 

In order to cope with the situation that may occur on different bikes, the dampers include two stainless steel screws, 10 and 13 mm each. You can be replace if needed!



Structural part: A + B 


 A.Spring:  Why we use a Japanese spring that has a longer stroke/ more softness instead of a hard spring? Because the harder spring coil will be thicker, hence a shorter stroke. If the spring can't absorb too much impact, the stress will be transferred to the rotating shaft under the frame. If this goes for too long, it may cause damage to the frame’s structure. This is not the situation we would be happy to see.



 B Superior glue:  The specially selected elastomer has special hardness, superior damping and allows for easy expansion. When the spring is compressed and squeezed into the elastomer, the elastomer expands to increase the friction on the inner side of the spring. The friction causes the spring to rebound. The speed is slower (like the principle of hydraulic springs), so that it can achieve both comfort and efficiency.


Therefore, the nature of the dampers should not be sacrificed! Under this premise, STIRLING DAMPER II provides the best road feel and comfort, and then we have added another new design to solve the long-standing Brompton frame clearance discrepancy!


When restricted by the original shock absorber design, you could not solve the problem of frame clearance, no matter what absorbers / shock absorbers / shock absorber bolts you changed.  The BIKEfun Stirling Shock Absorber II finally solves this imperfect small problem. With an elaborate adjustable structure, as long as the shock absorber is adjusted and aligned with the frame’s hook, it doesn’t matter if you use a stock or aftermarket shock hook, you will achieve a “zero gap” result. 

Practical installation and adjustment teaching:


From now on, if there are still friends asking us:

The rear wheel and the frame seem to have a gap on my Brompton and it will shake a bit. Is it normal?



 We will answer this way:


"It's normal with the stock standards! But as long as your bike is installed with the STIRLING DAMPER II, you can achieve the "normal" that you are looking for.”



More installation examples:



BIKEfun RAD. telescopic easy wheel bracket with the same anodized color matching




[Upgrade Focus.3] Brompton dampers. The Stirling damper and The IC. classic copper damper!
[Seatpost Clamp] BIKEfun Classical Seatpost Clamp, new technology merges with elegance.


Shopping Basket

Log in