is there any difference in strength between 25.5 & 31.8 bars & stems?

I’d guess it would vary wildly from stem to stem and handlebar to handlebar. I personally feel that the 31.8 systems I’ve used are stiffer, but again that was with different parts. A better question might be, “Does it matter?”

It’s not as simples as that. Depends on the design, material, weight, butting etc

it matters if you value your teeth 😆

Like-for-like a 31.8 set-up should be either stronger and/or lighter, just working on basic material principles.

For the same brand/model 31.8 bars and stems are heavier than 25.4

it matters if you value your teeth

classic

id be more worried this spindly bolt up the centre of my forks sheared than my bars or stem ….

or the circlip holding said bolt into the uppers slipped ….

oh dear – ive set the worry-o-meter off the scale with that one . if half the folks on here knew what was really holding the forks together they would shit an egg