Originally Posted by
tendency
Yes I use modern Shimano branded compressionless .. I'll make sure to use the supplied caps, but why does that matter?
Shimano makes compressionless brake housing? I was unaware of that.
If it's constructed like other compressionless housing, the metal wires that make up the housing run parallel along the length of the housing--not in a tight spiral as in standard housing. Braking exerts a pretty large force on the housing. A lot of this force is directed at "pushing" the housing from the ends. If you don't use the proper ferules, these wires can "squeeze out" of the housing ends, thereby destroying the housing. The compressionless housing I've seen is wrapped in Kevlar to prevent the wires from bulging out of the housing along the length.