Six out of ten, and that's being generous in the sandy bits. The Kep Track runs close to 70 kilometres from Mundaring out to Northam along the old Eastern Railway formation, and I rode the whole thing on the gravel bike a few weekends back after doing bits of it solo for years. It's a genuinely useful piece of infrastructure connecting the Hills to the Avon Valley. It is not, whatever the brochure copy implies, a smooth cruisy rail trail from start to finish.
What you're actually riding
The corridor follows the old railway formation that used to shift grain and timber through the Hills before the line was realigned. What's left is a wide, mostly unsealed path with the gentle grades you'd expect from something built for steam locomotives — nothing over a couple of percent anywhere, which is the whole appeal if you're not chasing climbing numbers. The catch is that decades without rail maintenance means the surface varies a lot block to block. Some sections near Mundaring are firm compacted gravel you could ride on 32mm tyres without thinking twice. Other stretches further out have loose granite scree and patches of deep sand where a skinny tyre will squirm on you.
Surface, gradient and what it does to your tyres
Drop your pressure before you start, not after you've already eaten dirt in a sandy patch. I ran around 35 psi front and rear on the gravel bike and it was still a bit much for a couple of the looser sections near the midpoint. If you're on a hybrid, you'll feel every bit of the corrugation the rail ballast left behind. A mountain bike is overkill for most of it but you won't regret the extra volume if the forecast has had rain in the week prior, because that's when the clay sections turn greasy rather than dusty. The gradient itself is a non-issue — this was built for freight trains, so nothing on the Kep Track will ever punish your legs the way the climb out of the Hills on a road bike will.
Starting from Mundaring, and why I'd pick it over Kalamunda
Mundaring is the better jumping-off point for this one, and I've made that case before in more detail in Kalamunda or Mundaring: the better Perth Hills day trip start. Parking's easier, the start of the formation is better signed, and you're not fighting through as much suburban traffic before you actually hit gravel. Kalamunda has its own merits for a shorter loop day, but if the plan is the full run out to Northam, start in Mundaring and don't overthink it.
Detours worth the extra time
If you've got a full day and don't need to be in Northam by a set hour, there are a couple of walking tracks that branch close enough to the corridor to justify locking the bike up for twenty minutes. Chidlow Road is an easy add-on near the Chidlow townsite and worth the stretch of the legs, especially if you've been sitting in the saddle for a couple of hours already. Further along, Trew Road gives you a different angle on the Hills bushland that you don't get from the rail corridor itself, which tends to run through cuttings and embankments rather than proper lookout country.
If you'd rather not ride it at all
Not everyone wants two days in the saddle to see this stretch of the Hills, and fair enough. The Full Moon Yoga Hiking Experience Mundaring works the same general area on foot and at a completely different pace, which I reckon is a smarter choice for anyone who wants the bush without the gear logistics. I wont pretend it scratches the same itch as a day on the bike, but it's a legitimate way to experience the same country.
Bike choice, tyre pressure and the Munda Biddi overlap
The Kep Track crosses and occasionally shares formation with sections managed under the broader WA trail network, and if you're serious about multi-day riding in this part of the state it's worth getting familiar with how the bigger picture fits together. The Munda Biddi Trail Foundation maintains a lot of the connecting singletrack and gravel further south, and their trail notes are genuinely more detailed than most state-run maps I've used. For route planning generally, Trails WA is the better starting point if you're stitching the Kep Track into something longer, since they'll flag closures and seasonal surface changes that don't always make it onto older PDFs.
On bike choice: gravel bike is the sensible middle ground for this ride. A road bike will survive it on a dry day if you're careful, but I wouldn't risk it with anything under 28mm tyres once you're past the halfway mark. The old hybrid I used to ride this on years back got the job done but it was slow going through the sandier sections, more wrestling than riding.
Getting into Northam and back
Northam itself is a decent reward at the end — proper town, real coffee, somewhere to sit down that isn't a servo forecourt. The practical headache is the return leg. Unless you've organised a car shuffle or you're happy riding back the way you came, you need to think about this before you leave Mundaring, not after you're standing in Northam at 4pm wondering how you're getting home. Most people I know who've done it either do an out-and-back from a midpoint, or sort transport in advance rather than relying on anything turning up.
So is it worth doing
Here's my genuinely mixed take: the Kep Track gets talked about like it's one of the must-do rides in the Hills, and I'm not fully convinced it earns that billing end to end. The Mundaring end is flat out the pick — good surface, decent shade, easy navigation. The middle third is where it gets patchy, literally, with enough loose gravel and sand to catch out anyone expecting a groomed rail trail the whole way. It's a good ride. It's not the standout some make it out to be, and I'd rather see new riders do the first fifteen or twenty kilometres properly than grind through the rough middle section just to say they finished it.
If you want something at the complete opposite end of the landscape spectrum after a day like this, the park notes for Kalbarri National Park Headquarters cover a totally different kind of country, red gorge rather than Hills bushland, and it's worth having on the list for a longer trip north. For now though, sort your tyre pressure, start in Mundaring, and don't expect the whole 70 kilometres to be as good as the first ten.