The $20 Niner Slacker Puck is very probably the cheapest geometry tweaking product we’ve come across thus far.

The Niner Slacker Puck is a lower external headset cup that effectively adds 15mm to your head tube length. It fits any head tube with a 56mm internal diameter, any tapered fork steerer and uses a ZS56/40 lower cartridge bearing

You’re either a tinkerer or you’re not. You’re either always thinking about tweaking or you’re simply enjoying the ride. Ignorance is bliss. A little knowledge is a dangerous thing. And plenty of other cliches.

Watch: Coil sprung enduro bikes test

If you are a bike geometry tinkerer then chances are you’ve already read our guide on How to change your mountain bike’s geometry. If you haven’t, go read it. It’s a good ‘un.

Niner Slacker Puck

For $20 you can get this Niner Slacker Puck and slightly slacken your head angle. How? By raising your head tube 15mm. By our reckoning this will slacken the head angle by less than one degree.

So not a massive change. But if you’ve already done everything else available to slacken your bike then here’s another thing you can try to eke some more slackitude out of it.

There are downsides.

It’ll raise your bar height by 15mm so you’ll have to do some stem spacer swapping at the very least to get your grips back to a familiar height.

The bigger issue is that the Slacker Puck will raise your bike’s bottom bracket height a bit. About 3-4mm. You can, of course run an offset shock bushing to re-lower the BB. Well, unless you are running offset bushings already that is.