Bottle holder - aluminium or titanium bolts? I'm a "weight-weenie" and optimize the bolts I'm using. Replacing steel with aluminium or titanium, depending of the location (to summarize: exerted forces, and dangerosity in case of breakage). Aluminium if possible, otherwise titanium.

For the bottle holders (two M5 bolts for each holder), people (fellow weight-weenies) say these bolts are amongst the less stressed, and aluminium can be used without problem. Some even use nylon bolts.

Though, I don't "feel it". Actually, I'm already using aluminium bolts here for months, and it seems to be okay. But these aluminium bolts are really lightweight, and I still fear they might break. Thus, I'm considering using titanium bolts here.

Do you think I am overfearing about the aluminium bolts and they are really sufficient, or not?

(FYI, I put a 500ml bottle on each holder, and I do city/road cycling, of course with some bumps here and there.)
i always avoid aluminum fasteners wherever possible due to a lot of bad experiences with them disintegrating over time (especially nipples on fancy wheels), but i'm not a weight-weenie, just weight-conscious.

i would say if you can afford ti bolts that'd be what i would go for, even though it's overkill and you'd be shaving maybe 1/10th of a gram. of course, if you were truly a weight-weenie, you'd leave off bottle cages entirely, right? ;)

if you're using this bike on a trainer, definitely avoid aluminum fasteners, as your bike is bound to be covered in sweat that'll accelerate the corrosion on the bolts. the things i've seen on trainer bikes.... disgusting. weight wouldn't be much of an issue on a trainer though so i imagine you'll be riding it in drier conditions.