Suntour rebound - loose knob

[Haibike_biker]

I have a brand new Cube Pro 800 Allroad with a Suntour Air fork. This has a red knob at the bottom of the fork, supposed to adjust the rebound. This knob sits loosely, if I leave it there I will loose it when cycling. When turning the knob, it is like unscrewing a screw inside the fork. The red knob has a long hex pin on it. I don't know how the rebound adjustment works, or whether it's supposed to feel a "turn" or "a click" when adjusting.

But isn't the knob supposed stick tight onto the bottom of the fork?

 

[PCeBiker]

I've also got Suntour air forks with the same red knob, and it doesn't unthread.

I've got 25 clicks from max-min rebound, then the rotation stops in both directions.

There's something definitely wrong with your adjustment knob.

Perhaps it's broken, or it was rotated with too much pressure when reducing the rebound and it unthreaded?

If it were me, I'd try to "tighten" it back up with a bit of force and see if it starts clicking/ratcheting when you reverse the rotation.

The ratcheting/clicking has a very light touch to it.

 

[stompandgo]

Let the air out of it before reassembling.

 

[PCeBiker]

Let the air out of it before reassembling.

Was my guess right?

Do you just tighten the knob back up?

 

[stompandgo]

It depends if the threads are still good. You just don't want to fight the air in the other fork chamber, if it exists.

Since the bike is brand new, I'd take it to the dealer.

 

[Haibike_biker]

It depends if the threads are still good. You just don't want to fight the air in the other fork chamber, if it exists.

Since the bike is brand new, I'd take it to the dealer.

You mean threads in the red knob? They are not screw in-out "threads" as far I can see, but "rings" with a rubber O-ring gasket.

 

[Haibike_biker]

Let the air out of it before reassembling.

How do I do that?

 

[stompandgo]

There should be a cap on the fork crown that when removed, has a Schrader valve inside. Depress the pin with a pick.

 

[PCeBiker]

The red knob has a long hex pin on it.

If this is the next pin that you are talking about, then the other end of it is probably threaded and has unthreaded from whatever it is supposed to screw into.

If it hasn't come complete out, then don't remove it.

How do I do that?

There is an air valve (Schrader valve same as an innertube) on the other end of that fork tube underneath a threaded cap.

There's about 200 psi of air in the fork and you'll need a shock pump to re-inflate the fork afterwards. (You forks will collapse when you let the air out.)

You don't wanna wreck anything, so if the dealer is riding distance away, then take @stompandgo 's advice and go see the dealer.
It's a brand new ebike.

Tell them that it was like that when you got it.