I have a bar bag on the three bikes I have with drop bars because you know ..... sandwiches.
There is a certain amount of "flapping" in use as they are just attached via the bars - either side of the stem.
On two there are no issues but with a short stem (80mm) on the third it knocks against the HT. I have helitape on the HT but its the noise that's off putting.
Have any of you seen a "thingy" to help limit this?
Is this what your after?
Alternatively you could get a handlebar extender from Amazon/eBay/AliExpress, mount it the the bars vertically down so the bag rests against these.
E.g.
Have any of you seen a “thingy” to help limit this?
I bought a Klickfix bag.
I use a wisecraker bottle opener headset spacer, keeps your bar bag from rubbing and opens your beer. So much win a little bit of cnc'd joy
That restrap bar linked above is supposed to work well. But beware, without a bar bag on, if your bars spin it could well put a ding in your top tube
I bought one of the Restrap Bumper Bars for my gravel bike but found the (quite sharp) ends of it snagged the brake hoses and gear cables. Lovely bit of kit but I took it off as I didn't fancy getting holes worn in the hoses.
You could try one of these & point it right down to support the bar bag.
But - it will add a bit of bar clutter to the handlebars & you might have the same issue regarding the comment above about it potentially dinking the top tube in a spill.
I used one to support a large Apidura bar bag on a bikepacking trip last year. It was fine.
You could always cut it down in size if you just need to support a smaller bar bag in the centre to stop it hitting the headtube.
I initially thought HT referred to HardTail, until I read the whole post.
Check out Jack the Rack? Might be a bit to big for your needs though
I got a jack rack. It works fine on 35mm stems.
It has improved my carrying capacity no end.
What is in your bar bag that you can hear it hitting the headtube? Mine is resting on the cables and hoses. If I'm carrying a proper load then it's my Revelate Harness and that's strapped around the fork crown too so there's no shake.
Foam spacers? I had some old floor matt things that I cut up to use for this exact purpose...
What is that rocket dog, ive seen them before but can't think where
Check out Jack the Rack
I've got one of these, I do like if but they are quite pricey for a small rack. Because the bar bag doesn't fill it, there's a fair amount of spare space up front for overspill.
Foam spacers, a length of paracord and a toggle work well to stop unwanted flappage...