As shop don't have this information:
Which round bases should be for Gigant Spiders (bigger ones):
- Will they fit on 50mm bases without going outside of the base?
- What base sizes are on shop images?
Which round bases prepare for upcoming trolls, will 50mm be enought?
Depends on the game you want to play I think, if your wanting LOTR I suggest watching the video for the Spiders: https://www.youtube.com/watch?v=1Q0077nJTZ8&t=8s
With Starship Trooper rules though, don't bother basing your spiders.
I'd want a side on picture on each page of the models with a comparison scale underneath, showing how big 25mm and 50mm would be in comparison.
That way you could work out roughly how big any bases would be on them, without having to use multiple shots and a huge number of variants for different games.
We're all adults, just give us the tools to work things out ourselves I say.
@Stilton Disco Actually that's why i asked "What base sizes are on shop images?"
I don't have the kit, but I believe the ones shown are on 50mm bases. I think they said this on FB, but I agree it would be useful information in the product description.