Modern replacements are crap! Sorry, but most are. I have had rubber bits go to cracked and junk while the bike is on the bench for a rebuild (Okay, admittedly I sometimes take a long time) but it is disheartening to have fork boots, kick rubbers, shifter rubbers and footpeg prophylactics crack and fall apart in short order.
Never use silicone based materials (its bad news and gets near your paint makes it hell for anyone to ever repaint again) But there ARE a few products that will keep your rubber bits pliable and near new. (Stay away from Armour All as well,,it makes it nice for a short while but accelerates wear and decay).
Glue or adhesive is generally not great for a kicker as with the motion of the kick, the rubber piece should not stay fixed or stationary... Rolls a bit under the boot. But I have seen and done it myself a few times is take some stainless acft safety wire (0.032 thou") and do 2 turns smartly around the end furthest away from the bike. Many kickers have a blob or knob on the end anyway so adjacent to that. Do the pigtail short and tuck it back in so not to protrude and stays on the underside out of site.
Use care when cinching up the stainless wire tight. You want it very secure but not so much as to slice THRU the rubber or distort it too bad. You just want to cinch things up near the proud end so it doesnt slip off. Remember about that rotate while kicking bit as well. (So, goldilocks tight, not TOO tight and not too loose)
many people secure grips this way too, and hoses instead of clamps. Done right it looks good, done wrong,, it looks bad. I am sure there is some dandy safety wire classes on youtube these days.
Also very handy tool to have to secure bits known to fall off. (its equally useful for airplanes and old Iron bikes)
(Dont poke your eye out!)
