"I've found that oversize 31.8mm can feel slightly stiffer and more reassuring than 25.8/26mm. Can be nicer to hold when on the tops as they are fatter. If you want to splash out fine, but as Barry says there's nowt wrong with 26mm......."
"Using something like that won't necessarily prevent snapped hangers/rear mechs but can help to some degree with mud build up and clogging elsewhere.
I've used dashboard shine but also Muc Off do a really good lube/protector/shine product…"
"If running clinchers, probably not worth it - use a track pump gauge.
If tubs, then that's a different matter as the lower pressures you can run really make a difference, and within that lower range, a difference of 1-2 psi can be huge.