Fancy forks – what are the nipple things at rear of fork legs for?

I’ve noticed these on some Fox forks and RockShox forks – what are they for? You seem to be able to push them, but they definitely don’t look like grease nipples.

I’m guessing they might be used to equalise or release air pressure, but what are they for and why are they a good thing?

Release air pressure from lowers

Ok, and why would you do that? Sorry, thick questions but I clearly don’t understand why you’d need to do that, ta.

They’re there for marketing and to attach bolt on mudguards to.

They’re meant to release pressure build up in the lowers from the pump action of the seals when repeatedly cycling the fork, but I’ve never seen it do anything.

pressure can build up in the lowers from certain scenarios like big altitude/temp changes, those allow it to be released, similar to the old zip tie trick.

Ah ok, ta. Had heard of a ziptie trick, but didn’t realise what it was for. Thanks for explaining it.

You’re lowers act as an extra air spring so if too much air gets pulled into them through normal use it can start effecting how the fork works, also large changes in altitude do the same so a press of each button just balances it out. It’s an easier and cleaner way of doing the zip tie down the seal trick. If you really want to feel the difference let all the air out your fork, compress them to full travel, press the buttons then pump them back up. This puts a slight vacuum in the lowers and makes the fork feel amazing over small bumps but blow through the travel. When forks were rubbish up until about 2015 we used to do that trick to make them work a bit better

Am I right in thinking Fox have patented them so Rockshox can fit them anymore?

New RockShox have a twist rather than press to get round the patent.

Automatic oil drain port if you use the new Whistler chairlift.

My new zeb ultimate are pushy button.