The Curtis AM9 is a heavy-hitting trail-cum-enduro hardtail designed to combine nimble handling with rowdy-terrain control.

With custom geometry as a no-cost option, or thoroughly modern stock numbers including a 64.5-degree head angle and 475mm reach on my size-large test bike, the AM9 can be tailored to your preferences.

Curtis has been hand-building steel bikes in the UK for more than 50 years. Today, the brand offers a range of stunning, fillet-brazed frames for a host of off-road and BMX applications.

With Reynolds, Columbus and Dedacciai tubing brazed together by hand, the AM9 is not cheap.

However, it’s a versatile hardtail mountain bike, with geometry that feels balanced, rewarding and ready to be pushed hard.

The steel frame has a lovely compliant feel in the rough but with enough brawn to plough through anything in its path.

Some care needs to be taken over how you build it though. Go burly with fork, wheels and tyres for a winch-and-plummet monster or play to its all-day comfort capabilities with a lighter, faster-rolling spec.

Curtis AM9 frame

Rather than welding the AM9’s steel tubes together, Curtis fillet brazes them.

It claims the benefit of this method is the tubes are airtight (apart from the seat tube). This means they won’t rust from the inside out as welded steel frames can.

Curtis says it has cherry-picked each steel tube for its ride-quality benefits. The front triangle is made purely from Reynolds tubing. This involves the brand’s 853 tubing for the top and down tube, while 631 is used for the seat tube.

The use of 853 is claimed to be because of its high strength-to-weight ratio. Curtis also says it gives the bike a lively ride character.

Dedacciai and Columbus steel tubes are used for the seatstays and chainstays. This is said to give the perfect combination of stiffness and compliance.

The tubes may differ depending on a rider’s weight or riding style. For example, if you’re over 95kg / 210lb and ride particularly hard, straight-gauge T45 is used for the down tube and seatstays.

Because each frame is made by hand, there are numerous customisation options. Buyers can choose from stock or custom geometry for the same £1,550 base price. A range of options can be specified at an additional cost.

These include candy paint colours or a smoked clear coat finish, standard or sliding dropouts and a custom frame number of up to six numbers or letters stamped into the dropout.

The basic frame cost is a heady £1,550. Candy or clear coat paint adds £50, while the sliding dropouts for rear-centre length adjustment, or easy single-speeding, are £120 options. Adding bottle cage bolts costs an extra £25.

Curtis AM9 geometry

As implied by its name, the AM9 is built around 29-inch wheels. To go with the big hoops, a 130-150mm fork is advised to suit its all-around, all-mountain intentions.

Curtis will build the frame with any geometry you like for no extra fee, or you can choose from five stock sizing options, from S-XXL.

Those wishing to alter the geometry can do so at no extra cost, giving you the option of choosing a shorter seat tube for modern, long-travel dropper posts.

Based around a 140mm-travel fork, my size-large test bike features a moderately slack 64.5-degree head angle, 75-degree seat angle, 475mm reach, 440mm chainstays and a 460mm (18in) seat tube.

The jumps between seat tube lengths on the AM9’s frame sizes are limited, ranging from 406mm on the small through to a lofty 508mm on the XXL.

In my opinion, the 457mm seat tube length on the stock size large is too long. If I was having a custom AM9 built, I would opt for a shorter length. The rest of the geometry is right in line with what I would expect for a bike in this category.

Curtis AM9 specifications

The AM9 is sold as a frame only, but Curtis supplied my test bike fully built with a range of components it had selected.

These included a 140mm-travel Fox 34 Factory FIT4 and matching Transfer dropper post, a mix of Shimano XT and XTR for the drivetrain, while British brands Hope and Renthal took care of the wheels, brakes and the remainder of the cockpit.

Schwalbe’s Magic Mary tyres in Super Gravity casing and soft compound were wrapped around the hoops.

I had a few niggles with my test bike’s spec, but I have not let these influence the score. They could easily be remedied if you were building the bike yourself.

Curtis AM9 ride impressions

I tested the AM9 on a variety of different trails, including trail centres, bike parks and off-piste chutes, as well as old-school cross-country loops.

It was treated to plenty of long fire-road drags and technical climb dab fests to boot.

Conditions were typically mixed for a UK summer, with bone-dry dusty singletrack mixed in with some proper slop fests.

Curtis AM9 climbing performance

The AM9 is a stable climber, but to make it pleasurable rather than bearable, wheel choice is critical.

Equipped with Hope’s heavy-duty Fortus 30 wheels and Super Gravity Schwalbe Magic Mary tyre front and rear, the rolling stock felt a real burden on longer rides, dragging significantly and robbing the bike of urgency.

Traction from the blocky, sticky tread and large-volume carcass was not lacking, but those same traits made fire-road climbs a real drag.

If you’re happy with a slow winch-and-plummet approach, as we’ll get to, they’re worth it going down. Given the bike’s all-mountain naming and intentions, I’d definitely go for a wheel and tyre combination that’s lighter and faster-rolling.

I swapped out the supplied setup for lighter Hunt wheels and Maxxis tyres. This opened up its potential for longer grinds in the saddle on big days out.

Geometry-wise, the relatively steep 75-degree seat tube angle gets steeper when the fork sags into its travel. This makes it easy to keep weight on the front end and keep it tracking where you want it to go.

That’s despite the relatively slack 64.5-degree head angle. This gets steeper as the fork sags, so feels more controllable on the trail than the numbers suggest on paper.

I had no front-end wandering on steeper sections. Keep your weight balanced and the AM9 has the potential to claw its way up some seriously technical pitches.

It’s never going to be a whippet uphill, nor is it intended to be. However, with lighter wheels and tyres, the Curtis would be an adept choice for riders who don’t mind a bit of climbing on their rides in search of the good stuff.

Curtis AM9 descending performance

If the Curtis has a Jekyl and Hyde character on the climbs, due to its kit choices, the same is true for the downs.

Those wheels and tyres make the bike feel as tough as most hardtails get on the downs.

With grippy rubber, a wheelset not afraid to deal with rim-banging descents, and Hope’s gloriously powerful and modulation-rich Tech4 E4 brakes, it’s ready to be rallied hard.

The 34mm Fox chassis and FIT4 damper did an acceptable job of suspension duties, but overall, I think Fox’s burlier 36 and more adjustable GRIP2 damper would further enhance the bike’s descending capabilities.

With a set of lighter Hunt Proven Race Enduro wheels and Maxxis Forekaster tyres though, the 34 felt more in keeping with the spec’s all-day pedalling credentials. I’d still prefer the more adjustable GRIP2 damper, however.

Once again, this shows just how critical fork and wheel choice is to unlocking the AM9’s dual personality.

The 64.5-degree head angle felt well-matched to the bike’s intentions. It’s fast enough that it can whip through tighter sections, yet it also offers stability at speed in the rough stuff.

My bike’s 475mm reach and 440mm chainstays made it easy to keep centred. I could get my weight back on steeper sections or push on the fork to weight the front wheel in corners without upsetting the bike’s balance.

However, the low 306mm bottom bracket meant I had to keep an eye on the pedals when trying to maintain momentum on rough but flatter gradients.

As for that ‘steel is real’ feel, the AM9 certainly delivers. It doesn’t whack you through the pedals like some alloy hardtail frames. You’ll still know you’re on a hardtail, but bigger hits are definitely more muted.

It feels fluid over smaller stutter bumps, but there’s enough muscle in the front end that high cornering forces and big compressions don’t fluster it.

It certainly feels pretty bomb-proof and I’d have few concerns about going as gonzo downhill as my (or a more skilled rider’s) ability would allow.

Overall, the AM9 is a very competent descender. It felt planted yet reasonably agile and gave me the confidence to push my limits. Riders who want a flat-out fast hardtail for the descents won’t be disappointed.

Curtis AM9 bottom line

The AM9 is a stunningly built frame. The fit and finish are among the very best around. While you pay a premium price compared to its off-the-shelf rivals, it’s easy to see where your money goes. Few bikes I’ve ridden have attracted as many admiring comments as the Curtis.

The geometry, steel tubing and tough demeanour instil a real sense of confidence in its ability to let go of the brakes and go wild on descents.

On the flipside, the comfortable seated climbing position and not overly wild head angle mean it’s equally happy on mellower gradients. Big miles or serious smiles, it can do both confidently.

Whichever side of the coin you choose when building your AM9 though, just be sure to match the fork, wheels and tyres appropriately. Go lighter or stronger, don’t try to mix both.