NS Bikes Define AL 150 is a modular trail bike available with 130 or 150mm of rear travel. Flipping a chip in the lower shock mount allows you to slacken the head angle and lower the bottom bracket height, even mid-ride. Excellent build including Fox suspension at both ends, a SRAM drivetrain and our favoured Guide RE disc brakes. There are four bikes in the Define 150 range, with our test bike being the cheapest.

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If you go to the NS Bikes website and compare the Define Al 150 with its shorter-travel sibling, the Define Al 130, you’ll notice that both frames are identical – the travel and geometry changes a direct result of different rear shocks and lower shock mounts.

A different shock and shock mount is all that defines this, um, Define from its shorte-travel stablemate

Using a modular design and building two bikes from one frame isn’t particularly unique or innovative, as plenty of brands use shared frame components to build other models in their line. The difference here is that NS is totally open about it. And while both bikes have their own intended use, if you really wanted to, you could easily swap the mount and shock on one bike and turn it into the other. NS even sells the different shock mounts for £89.99 to do just that.

Cabling sits in recessed channel in down tube

But let’s get back to the Define Al 150. As the name suggests, it gets a hydroformed aluminium frame with 150mm rear travel. The rear shock is a Factory-level Fox Float DPX2, but out of the box it felt a little dead. I wound off most of the rebound damping to get a bit more pop out of the rear suspension and that helped a lot in terms of liveliness, but it also pushed my weight forward onto the front end, which unbalanced the bike when descending. The shock also feels like it ramps up too quickly, so I always felt a little short-changed in the rear suspension department too.

NS’s Rotary hubs won’t let you down and neither will SRAM’s Guide RE brakes

This doesn’t seem to hold the NS back though, thanks in part to the modern geometry on the size large that boasts a generous 1,270mm wheelbase and relatively low 332mm BB height. The trade-off? Well, it sure pedals like stink. Still, when you have 150mm of travel at your disposal and a 160mm fork, you expect to be able to get loose, but when riding steep technical trails I felt like I was hanging on instead of letting it all hang out, like a passenger rather than a pilot.

This disconnected sensation isn’t helped by the hard-compound NS grips and skinny race-focused saddle. The rest of the build kit is good though, and the bike is well finished – the Define Al 150 nicely coordinated with copper details. The NS stem has a split-clamp arrangement similar to a Renthal stem and, while set-up is a bit more involved because you have to slide the clamps down the handlebar first, it’s lightweight and stiff.

Tapered head tube boosts stiffness at thefront end

You also get a reliable X-Fusion 150mm dropper post on the size large, and the frame has a good ream depth so we could make full use of the drop. Standover clearance is also excellent and there’s space for a full-size water bottle on the down tube. More critical is that the chainstays are also slimmer at the dropouts so you don’t catch your heels, like on the old NS Snabb, the precursor to this bike.

Loose cabling under the BB is a recipe for rattle

NS also fits excellent tyres, combining a grippy Maxxis Minion DHF Maxx Terra up front with a faster-rolling Aggressor on the rear. Traction is nothing without control however, and NS has that covered too thanks to the SRAM Guide RE brakes which bring good modulation, smooth power delivery and excellent feel. So apart from some new grips and a comfy saddle, there’s really very little we’d change on this bike, as it has a cracking build for the money.

Quality Maxxis tyres are a welcome item on the spec sheet

Still, if you’re spending nearly £4k on an aluminium trail bike you’d expect good value, right? But you also want it to sparkle. So even though the NS Bikes Define Al 150 is efficient and well specced, the ride quality is just good rather than outstanding.

Bomb-proof split-clamp stem comes without a weight penalty

Don’t get me wrong, you can have fun on this bike and it covers ground efficiently, but when it comes to really busting moves, it just lacks a little bit of confidence. Also, there are only three frame sizes (small, medium and large) which means if you’re over six foot tall there isn’t a size that fits.