I have a frankenbike with rigid carbon forks & a 29″ front wheel which is better to ride than it sounds/looks.
However it has straight bars atm which I want to replace with low risers.
Is it worth spending extra for some carbon bars to reduce trail buzz on longer rides/enduros/marathons?

Yes.

It definitely makes a difference. I fitted carbon risers to my Ti XC bike, replacing the flat ally ones I had.

You’d probably see a bigger reduction by letting a few PSI out of your tyres. But if you fancy carbon bars then pick one of the manufactures who’ve been doing it for a while. Easton Raceface etc.

I dunno if it makes a difference, having only had carbon bars on bikes with sus forks. Some are lighter, such as the Easton CNT ones.

Yes.

I expect it’d make even more difference on a rigid bike, though I’ve only had them on bikes with sus forks and they’ve been one of the most worthwhile upgrades I’ve made.

looks like it’s spendy spendy time 🙂