>>1805120They allow to make a very tight cable routing around the bike without causing additional friction of compression issues.
Depending on a bike - they are great to route around the BB, to the RD or mechanical disk brake.
On my gravel - I use the noodles to route to the rear brake ( from the chainstay ) and to the front mech, so can route cable from the downtube instead of having an ugly cable on the top.
The RD on that bike uses a mechanical contraption called "Rollamajig" by Avid. No longer produced, but it allowed to avoid the godawful loop of cable on older type of shimano RDs.
Pic rel - using a noodle to route a cable along the chainstay on my enduro bike.
