What is crush tube?
Answers:
Crush tube - I use the term "bearing" or "distance spacer". It's easier for people to understard what I'm talking about. It's used in wheels & swing arms and any moving part that uses bearings.
-The crush tube's intended purpose is to make sure that there's even pressure on the inner race of the bearings in an effort to prevent any unforseen lateral movement which could possibly lead to premature bearing failures.
-In other words, when you tighten a wheel's axle, the wheel spacers (between the wheel bearings and swingarm) will apply force against the inner race of the wheel bearings toward each other. The crush tube prevents that, by keeping a set distance between the bearings.
-Here's an example -
http://www.bikebandit.com/partsbandit/oe.
Go to - 1987 - Honda - XR250R - Rear Wheel #9