Ming Cycle's reply to ST-QRS-001/saddle bolt request

Dear forum members,

on 06.11.2010 I sent a request with two technical questions mentioning the Strida Quick Release Seat Molding and the Strida saddle bolt/nut to mingbike@ms9.hinet.net

As there was no reaction till 16.11.2010, I sent the message to info@vanmoof.com , who kindly forwarded it to Ming Cycle. Thanks to VANMOOF/The Netherlands!

Here is the message:

Here the attached pictures:

QRSmod 01.jpg

QRSmod 02.jpg

QRSmod 03.jpg

On 18.11.2010 strida-global@strida.com replied:

I wrote back:

On 23.11.2010 strida-global@strida.com replied again:

:confused: This time I replied, on 25.11.2010:

Here the newly attached pictures:

seat pin 03.jpg

Q/R locking mount.jpg

saddle bolt 01.jpg

This for now, here we have Wednesday 01.12.2010 0:00 am
I will post answers of Ming as soon as possible.

The reply on 02.12.10:

Dear members, what do you think?
Your suggestions, opinions or whatever are highly appreciated.




Sorry for my late opinion… :cry:

With your new Height Adjustable System, it could be difficult to secure that the Seat Pin is always positioned properly. Even the checking seems difficult.
In the original system, ‘Setting the pin’ is the first step of the total assembly process :wink:


Hi Binch Shin,

many thanks for your reply, better late than never! :slight_smile:

Sadly, I am not able to fully understand what you mean with “positioned properly”?

There are two holes in the frame tube, the upper and the lower possibilities to insert the seat pin.
To be more precise, we actually have four holes because the tube is hollow.
So, let’s say we have two holes pointing in driving direction and two holes are pointing backwards.
The seat pin will be mounted in any case (regardless of original or modded version) through one of the backward holes, which contain the threads for the seat pin, at first.
Once the backward hole is passed by the seat pin, there are certainly just two possibilities left:

  1. The seat pin WILL NOT find the corresponding, forward pointing, hole.
    That means the tip will bump against the inner diameter of the tube, the thread of the pin will not find its corresponding thread, it will be possible to turn it around a little, but not to fix it properly. Furthermore, if the seat pin has been mounted “that wrong way”, it will be impossible to mount the Q/R seat molding (using original parts) or it will be impossible to move the seat molding up or down (using a modded seat molding). Also the Q/R locking lever needs the tip of the seat pin for correct function, but more about that below.

  2. The seat pin WILL find the corresponding hole.
    The small conical area at the tip of the seat pin supports this action, the seat pin’s thread will find its partner in the hole without any problem, and the bolt can be fixed properly by turning clockwise.

So, in my opinion, the seat pin might be mounted in just two ways:
“Positioned properly” or not, absolutely regardless of what seat pin or seat molding has been used!

Yes, checking might be difficult when the seat pin is blackened… :sunglasses:

Below, the inside of the Q/R locking lever (red) with attached Q/R locking lever safety hook (black) can be seen:

In correct mounting position the Q/R locking lever sits on the tip of the seat pin, secured with the plastic hook. The tip fits in the round, deeper hole inside the arrowed shape.
If the seat pin is not in its proper position, the Q/R locking will slip to the top of the Strida, each time unlocked, and loose its functionality or fall off.

Yes, according to the manual, page EN-4, chapter “Installation”, step 1 :
“Ensure the seat pin is fully tightened.”

The installation process in 18 steps will be equal, whether original or modded version.
The 8-step process mentioned above belongs to the height adjustment of a modded version only!

More comments on this topic are highly appreciated!

Best regards


I have two thoughts:
1. if you insist Easy Movable Seat-pin then your idea is the best solution including less modifications. There would be no structural imperfection (that I could point out :wink: )
2. Ming Cycle Engineer’s advice is considerable : #4.We don’t recommend to move the pin often, because it may not be tightened enough, the hole may become bigger, all cause the safety problem. Following my engineering experiences, aluminum thread doesn’t lead its bolt precisely through itself… sometimes it’s hard to notice Going Wrong…


Hi Binch,

Knowing that you are a mechanical engineer and designer, your words are a precious affirmation, thanks!

True for sure, but where is the problem?
Might this be caused by missing lubrication?
I think the biggest problem is the inappropriate material pairing, in this case aluminium/steel.
This sort of material pairing, just like stainless steel/aluminium or even stainless steel paired with stainless steel, always tends towards galling or seizing without using an anti-seizing lubricant.
(That’s exactly what I mentioned about the saddle bolt/nut combination, and I am really surprised that Ming’s technicians have never heard about such things - point 7. of Ming’s reply.)

Ming’s engineers are certainly trustworthy, but one thing makes me really perplex, at point 6.:

“Yes, the top and bottom Q/R lever clamps MUST transfer the FULL weight force of the rider to the frame. The pin is to fix the seat moulding and avoid it to move down & around. We tried to use the QR seat moulding without pin in the beginning, but it moves down somehow.”

Dear Binch, please correct me if I am wrong, but in other words this means:

Sometimes, caused by “somehow”, DOES the seat pin transfer ANY WEIGHT!
Otherwise the seat pin would not be able to stop the slipping process…

I hope to keep your interest running…


Hello BSA

I think the problem is originally from the low strength of aluminum… As you know, the thickness of rear-tube is very small. The length of thread is quite short :open_mouth: The thread can be easily spoiled by a mere force. So I agree Ming’s advice, “Don’t change the pin position often.”

To analyze this mechanical matter, a recommendable approach is to choose knowledges of Static Friction. Before the seat-moulding slips actually (with an actual velocity), the seat-pin would take a small portion of weight. Physically : WEIGHT = Big frictional force of moulding + Small shear force on seat-pin :wink:

I have been waiting for a Height Adjustable Seat for a long time. I wanted it because lower seat is safe for running down and higher seat is helpful for climbing up. And now Ming’s solution is satisfactory. (but I didn’t buy it yet :mrgreen:)

Although I am not in the Strida business, your demand seems not usual… not acceptable for many of Strida riders. Sorry to say this :cry: