When I started to build my new bike I thought the answer to this was yes – I watched all the youTube videos and I was sold.
But I couldn’t get one for a reasonable price…
So I tried to do without. And you know what? I found out that I didn’t need one after all. And you might not either.
The challenge is actually pretty straightforward: can you reach the cable cutouts in your frame if your fork is removed?
If you can, then you don’t need an internal cable guide.
If you can reach the cable cutouts by your head tube with your fingers, then you don’t need tools to guide your cables/hoses.
Make sure you feed your cables from the back of the bike to the front of the bike – which is what you have to do with your rear brake and internal dropper cables anyway – and you should be able to relatively easily pull your cables through the frame.