This riff is in 4/4 but thanks to it’s heavily syncopated 16 note pattern you’d be forgiven for thinking it is in something more exotic. It’s all played on the D string – and it’s worth noticing that Justin Chancellor always uses a pick, so if you’re after that pure Tool sound go get one now!
I like to break it down into two sections to make it easier to learn and play. Even if you struggle to read notation, this method should help you ‘feel’ the rhythm in each section. Arguably the trickiest part of the bassline is the second half – which doesn’t begin on the first beat of the bar and thus is the bit that can easily throw you off. If you count in sixteenths, you’ll soon realise it’s on the third 16th.
In fact, if you break down the line a little and play with variations on the ghost notes, you can quickly find similarities between this line and something like For the Love of Money by the O’Jays!
Like the opening riff, this is a heavily syncopated line which in isolation owes more to funk and jazz than the traditional driving rhythms of metal and rock. Importantly, you will have to play in drop D tuning (i.e. tune your bottom E down to D).