Santa Cruz Heckler SL GX AXS Carbon C review | Electric Mountain Bike of the Year contender

The Santa Cruz’s Heckler SL’s lightweight battery, motor and spec slip a full bike comfortably beneath the 20kg mark; the size-large GX AXS C model weighs 19.54kg without pedals.

Using Fazua’s impressive Ride 60 motor – boasting peak 60Nm of torque and 450W of power – it’s powered by a 432Wh on-board battery.

This SRAM-built bike gets a 160mm-travel Lyrik fork and Super Deluxe shock, taming 150mm of rear-wheel travel and GX AXS Transmission, along with Code Bronze Stealth brakes, all costing £8,799.

Running a mixed-wheel setup (29in front, 27.5in rear), it has a flip chip to adjust geometry between high and low settings.

A 64-degree head angle is paired with a 77-degree seat tube angle, a 480mm reach (large) and size-specific chainstays.

On the trail, the Heckler comes alive when ridden hard and aggressively. While there’s plenty of suspension travel on tap, the way it’s delivered means it only numbs bumps rather than absorbing every imperfection.

This feels great when you’re on form, riding hard and with intent; the bike has a granite-like constitution and feels as though it loves to be worked hard.

Back off, lose concentration or get off-line, however, and that same solidity means it won’t save you when things go wrong.

The Fazua motor’s power is brilliantly delivered and abundant, while battery life is commendable. However, the seat tube angle and over-the-back feel really limit the type of terrain you can scale comfortably.

Santa Cruz Heckler SL GX AXS Carbon C frame, suspension and motor

Built from the brand’s C carbon fibre – that’s marginally less expensive and heavier than the fancy CC material – the Heckler SL’s shape is reminiscent of almost every other model in the brand's line-up.

Cables are routed internally via ports next to the head tube and there’s masses of underslung down tube and chainstay protection. It runs SRAM’s Universal Derailleur Hanger and has a single bottle mounting point within the down tube.

The 150mm of rear-wheel travel is doled out by Santa Cruz’s VPP suspension design. Co-rotating links join front and rear triangles, while the lower link gets a geometry-adjusting flip chip and grease ports to keep the bearings running sweetly.

Fazua’s slim Ride 60 motor and 432Wh battery deliver the assistance. Although motor output is adjustable in the Fauza smartphone app, peak figures are impressive at 60Nm of torque and 450W of power.

While currently unavailable, Fazua has promised a range extender for the Ride 60, adding 200Wh of extra power.

Santa Cruz Heckler SL GX AXS Carbon C geometry

The aforementioned flip chip adjusts geometry between high and low settings. The head angle can be switched between 64 degrees (low) and 64.5 degrees (high), while the bottom bracket height changes from 340.7mm to 344mm.

Reach figures range from 435mm up to 525mm in the five-size range (S to XXL). Chainstays are size-specific, too.

Small to large sizes get 443mm rear ends, while the XL ups that figure to 446mm and the XXL extends it further to 450mm.

The effective seat tube angle hovers around 77 degrees across the range of sizes and geometry flip chip positions.

Santa Cruz Heckler SL GX AXS Carbon C specifications

A 160mm-travel RockShox Lyrik Select+ fork is matched with a Super Deluxe Select+ rear shock. Sticking to SRAM, there’s GX Eagle AXS Transmission gearing and Code Bronze brakes.

A WTB Silverado saddle is affixed to OneUp’s V2 Dropper. Santa Cruz’s 35 Carbon bar is paired with a Burgtec Enduro MK3 42mm-long stem.

Santa Cruz’s Reserve 30SL AL rims are laced to DT Swiss 370 hubs, and wrapped in EXO-casing Maxxis tyres (Minion DHF front, DHR II rear).

Without pedals, the size-large Heckler SL GX AXS Carbon C weighs a respectable 19.54kg.

Santa Cruz Heckler SL GX AXS Carbon C ride impressions

The Heckler SL was tested on my home trails in Scotland’s Tweed Valley, host to world-class enduro and cross-country racing.

I took it to the gnarly, steep enduro trails at the Golfie and the flow trails at Glentress, plus everything in between to really push it to its limits.

Setup

Setting up the Heckler SL’s suspension was simple. I inflated the Lyrik’s air spring to 70psi – slightly less than recommended (77-78psi) – and installed a single volume-reducer spacer. I fully opened all the external compression and rebound adjusters.

At the rear, the Super Deluxe Select+ shock only has rebound adjustment, which I opened fully. I inflated the air spring to 200psi, giving 28 per cent sag.

Feeling natural right away, I left both the fork and shock’s pressures unchanged for the whole test period.

Santa Cruz Heckler SL GX AXS Carbon C climbing performance

Uphill, the Heckler SL’s seated position has a rearward bias, concentrating a higher portion of your weight over the back wheel.

Caused by the slack-feeling 76.6-degree (measured) effective seat tube angle, your hips sit behind rather than over the bottom bracket.

Angling the saddle nose down and pushing it forward in the clamps helps reduce this sensation, but doesn’t cure it, and is only a workaround for slightly compromised geometry.

Angle skyward on a steep gradient and the front wheel is eager to go light. Unless care is taken to control it, it lifts as it bounces into bumps, rocks and roots.

Without actively weighting the front with overt body shifts towards the bar, control and accuracy are limited.

Here, balancing steering precision and rear-wheel grip is a juggling act; one false move and wheelspin is inevitable – another and you’ll be drifting off-line.

This is exacerbated when you’re operating at nine-tenths to tackle the most heinous inclines.

Matching the motor’s power output with your legs – by putting in plenty of power and spinning the cranks quickly – leaves little bandwidth in your body’s articulations to make up for a compromised seated position or reduce front-wheel wander.

Although fairly supple, the VPP suspension only takes the edge off bumps rather than ironing them out. This is great for efficiency and the taut ride doesn’t interfere with forward progress, but comfort and traction aren’t its standout qualities.

All said, however, mellow fireroad climbs are comfortable; the suspension and geometry combine for an event-free ride. Here, its performance is more neutral than negative.

Motor performance and battery life

Fazua’s Ride 60 motor has plenty of poke. Both torque and power figures are delivered generously in all but its lightest Breeze mode.

Gliding to the trailheads or tackling undulating singletrack is fun and fast. Exceed the motor’s cut-off and you’re not lugging about dead weight, either. Pedalling hard makes for sprightly progress.

Best of all is the battery life. If used conservatively, well over 2,500m of ascent is possible from a single charge. Sticking to Rocket – with generous helpings of the spicy limited-time Boost function – I still hit over 1,000m.

The ring controller feels cheap, however; its magnetic rotating design can stick in position.

The switch’s throw makes selecting the Boost mode (a long twist forward) tricky when the terrain is challenging, which is where you’ll need it most.

But of all the lightweight ebike motors, the Fazua is still sitting in the top spot.

Santa Cruz Heckler SL GX AXS Carbon C descending performance

Epitomising the lightweight ebike feel, the Heckler SL can be popped, bounced and jumped down the trail.

Switching, picking and crossing lines, changing direction is easy and engaging. Still feeling confidently controlled, the motor and battery’s additional mass – especially compared to a human-powered trail bike – help mute unwanted liveliness.

The suspension chips in, too. An abundance of support means driving the bike into the ground doesn’t gobble up much-needed reserves put aside for bump absorption.

Generous bottom-out resistance means it’s unlikely you’ll feel the Hecker SL’s rear end reach a hard stop.

As when climbing, it's not the most active; it's lazy, even. It doesn’t track the ground with surgical precision, instead absorbing every one in three bumps.

Treating it as a blunt instrument extracts the best from it, though. By working it hard into the terrain – in the same way you’d flatten bent metal using a lump hammer – it responds not with a whimper, but increased speed, control and dynamism.

In this respect, it’s wonderfully inert; you can thrash about atop it, commanding the exact route it takes without a groan, grind or grimace.

But you’ll need to keep your wits about you.

Although the high front end and low bottom bracket create an ‘in’ rather than ‘on’ feel, it still encourages you to weight the front wheel on steep descents or super-technical sections. However, as soon as you disengage or get lazy, it doesn’t take long to get wild.

It won’t save you if you shoot off-line or turn into a passenger; a plusher ride would certainly help here, but may also detract from its hard-charging blunt-force character that’s so much fun to ride aggressively.

In this respect, the full-power Heckler’s sofa-like family lineage hasn’t been passed down to the SL version.

Quite a bit of control could be won back with burlier tyres. While Santa Cruz has selected the right compounds – a MaxxGrip up front and MaxxTerra at the back – it has skimped on the casing to save weight.

EXO casings, while light, feel undamped. They’re also more suited to lightweight trail riding rather than a 19kg ebike.

As a costly upgrade – up to £80 an end – Santa Cruz should be fitting better tyres from the factory, especially given the nigh-on £9k asking price.

How does the Santa Cruz Heckler SL GX AXS Carbon C compare to the Giant Trance X Advanced E+ Elite 1?

Although both comfortably positioned as SL eMTB trail bikes, the Trance X and Heckler SL are leagues apart.

On the ups, the Giant will race away from the Santa Cruz thanks to its full-power motor. Its geometry means there’s heaps more control, as well as being more comfortable, especially when the going gets really tough.

Battery-life supremacy falls firmly in the Heckler’s camp, even with the Giant in a de-tuned state; you’ll still be riding the Santa Cruz long after the Giant has gone back to be recharged.

Both share issues with tyres. The Giant’s dual-compound EXO-casing Maxxis tyres are beaten by the 3C versions fitted to the Heckler by quite some margin, even if neither are perfect.

On the downhills, the Heckler is the standout performer, even if its suspension is less forgiving and supple. Control lost here is made up in spades by its geometry; it makes the Trance’s head angle look positively old-school.

Of the two, I’d choose the Heckler, but would also warn there are better-performing bikes out there.

Santa Cruz Heckler SL GX AXS Carbon C bottom line

More hammer than blade, the Heckler SL likes to be ridden hard. Pushing it into the trail, smashing it over rocks and roots, or popping and bounding your way through tech is the preferred method; ridden like this, it’s brilliantly fun and fast.

But a lazy or uncommitted style is punished. It won’t do any of the heavy lifting for you and beginners might struggle to get the most from it.

A slack-feeling seat tube angle caps climbing performance, limiting control and grip. It’s a shame because the Fazua motor is brilliantly powerful and can last an age in the more frugal settings.

The Heckler SL has a ravishing appetite for speed on the way down, but is limited elsewhere.