Sub 10kg (22lb) has always been a benchmark for the best lightweight mountain bikes. However, with XCO courses becoming more and more technical and riders demanding bigger tires and dropper posts to tackle them, 10kg bikes are rarer than ever. That's not to say it isn't achievable, many bike brands manage to get their best full-suspension mountain bikes under the 10kg mark.
In reality, you’d be hard-pressed to tell any difference in the ride between a 10.2kg bike and a 9.8kg bike but the psychological/bragging rights of going under 10kg is massive. Developments and demands of riders mean it’s harder than ever for cross-country mountain bikes to hit that target though. 29in wheels, tires and forks will always be heavier than 27.5in or 26in (remember them?) but their smoother speed makes them an XC essential. Some top racers like Nino Schurter are routinely using 2.4in tires now too, while others are wide rim or wide handlebar fans.
Most of the world’s fastest racers are now using dropper posts for extra control on challenging courses despite a 400-500g penalty over fixed posts. Huge cassettes mean simpler 1x transmissions are often heavier than old double chainring setups too. Even fitting a remote control lockout to the best XC forks adds significant weight, but again most racers won’t be without it for smashing smoother climbs.
Keep reading for our list of the best lightweight mountain bikes available, or skip to the bottom if you are want to find out what you need to know about the best lightweight mountain bikes.
Best lightweight mountain bikes under 10kg
At 820g for a medium frame with rear axle and seat collar (averaging 760g/1.72lb without), Specialized’s new S-Works Epic HT frame is one of the lightest mass-production mountain bike chassis you can buy. Not only is it available in a full range of sizes - unlike the Unno - each size gets a slightly different ‘Rider First’ layup to deliver the right ride-feel. Unsurprisingly that’s the cliched ‘compliant over bumps but powerful through the pedals’ character touted by most manufacturers. The super-skinny, blade top seat stays combined with a deliberately damped 30.9mm seatpost to deliver a genuinely forgiving in-the-saddle ride. The sculpted front uses a Brain-equipped, 100mm travel, RockShox SID Ultimate fork. The fork crown uses a short offset for extra stability and the head angle is relaxed at 68.5-degrees. Add ‘short for XC’ 60-70mm stems and 760mm wide handlebars as standard and it’s a surprisingly composed charger on descents. The 30.9mm seatpost size gives you a full range of dropper options, too.
If you’re looking at a sub 9kg bike though you’re probably mostly about the acceleration kick and climbs, and Epic definitely delivers here. It’s not ‘Euro lab test’ rigid underfoot but there’s no trace of morale-sapping twist as the revs drop and the torque peaks. Specialized even fits a Quarq power meter to this flagship AXS spec as standard because it knows watts are as important to racers as weight. The automatic bump sensor built into the Brain fork lets you tune the rigid-to-flowing balance in a uniquely binary way and frees you up from fretting about remote levers, too. It’s got practical as well as podium-hunting detail with a threaded bottom bracket fit and clearance for up to 2.4in tires.
Decades of supporting many of the world’s top racers mean its own brand kit is seriously light, although its low spoke count (24 upfront) wheels can be a bit wayward when worked hard. If you can’t afford this flagship there are four different complete Epic HT bikes down to $2,400 / £2,250 and a frame-only option.
In terms of frame weight, Orbea’s carbon fiber Alma OMR race hardtail isn’t crazy light at over 1kg, but they’ve done something radical to get complete bike weight low enough to kill on the climbs. Depending on what fork you run, Orbea’s 550g Spirit Rigid fork will save you 800-1,000g over a 100mm suspension unit to bring complete bike weight well under 9kg. The kinked, super-flat top tube is designed to help dissipate the extra shock coming through from the front end too, although the long, tapered, carbon legs deliver a smoother ride than you’d expect. The super-slim stays are designed for extra flex but there’s still plenty of meat around the cranks and chainstays for kicking hard and making that low weight count. The fork is also the same length as a 100mm travel unit so swapping around won’t disturb the agile, short wheelbase handling.
The same OMR frame appears on the top four Alma models with another four Alma models using the slightly heavier OMP frames. Whatever your starting point, Orbea’s ‘MyO’ customization program lets you pick and mix from a range of components to tune cost, weight and character. You can even choose from multiple color options (fully custom on the top models) so that you get a truly personalized Alma built for you in Orbea’s Basque factory. The direct sell model means they’re generally very good value too although you will have to wait longer for delivery than if you pick an off-the-shelf bike from your local shop.
Mondraker has redesigned the Podium hardtail for 2021, so it has a more conventional look but keeps its lightweight and 'Forward Geometry.' The brand claims that it has created the world's lightest production frameset.
Born on DH race tracks thanks to the work of Unno’s Cesar Rojo and others, Forward Geometry was the spark point for the current trend for super-short stems on extended reach frames. Mondraker was the first mainstream brand to be bold enough to use the concept right across its range from gravity bikes to cross-country machines. The Podium was designed a while ago now but the 2021 model's geometry has been refreshed, bringing a 463mm reach, 68.5-degree headtube angle, and a 70mm stem on a size large.
If you can afford the price tag for this beast of a hardtail, then you'll be smashing the climbs in no time.
Santa Cruz’s original Highball race hardtail was so stiff it could make your feet numb in under an hour in the wrong shoes and rattle teeth out on rocky descents. That meant we weren’t expecting an easy ride when we met its new race rod. Santa Cruz has completely flipped priorities with the new Highball though, realizing that fighting fatigue and preserving performance is more important than ultimate power punch. While the 69.5-degree head angle is still pretty snappy the 450mm reach (large size) is long for an XC bike, which helps calm control on flat-out fast sections. The frame compliance also noticeably improves the bike’s ability to conform to the trail for traction as well as reducing the chance of you being rattled offline or ricocheting randomly off rocks and drops. The threaded bottom bracket and three bottle cage mounts are designed for the long haul. Despite removing over 200g from the old frame it gets a no weight limit, no questions asked, lifetime frame warranty.
Riders can also opt to equip their Highball with Santa Cruz’s Reserve carbon wheels. They’re covered by a similarly no-nonsense lifetime warranty and again the ride feel is obviously damped and shock smoothing rather than skittish and sketchy. That means you can hit stuff hard without worrying about comfort levels or construction quality and it’ll work great as a daily driver.
Unsurprisingly, power delivery definitely isn’t as taut as some pure racers, but trail connection and rollover performance are excellent.
A couple of years ago now, Trek created an all-new type of full-suspension bike, using what it calls ‘Isostrut,' a tiny but full feature remote control Fox air shock, hidden inside a Kashima gold stanchion that bolts into the cutaway top tube. The flat flex stays then stretch forward to a tube that slides along the stanchion, connected to the shock via top and bottom slots that also stop twist. Add a main pivot just above and in front of the chainring and you’ve got 60mm of travel with all the usual shock rate, pressure and damping adjustments plus a remote control lockout. Fewer pivots and linkages mean reduced mass and maintenance and it also gives a very clean frame look with room for two bottle cages if the race/ride is long or hot.
Trek has certainly committed hard to the concept too, with no carbon-framed, purely hardtail bikes in its XC lineup. ProCaliber 9.7 and below use its road-bike-derived ‘IsoFlex’ scissor frame. Meanwhile, the new Trek Top Fuel beefs up from its previous super-light and twangy incarnation, getting 115mm of travel out back with slacker angles, longer reach and a much stiffer power and precision-friendly ride.
While we personally have not tested the Isotrut-equipped Super Caliber yet, the top racers in the world seem to have no problem making it go fast on the trails. This is a very "XC" bike, so the unique design certainly won't be for everyone.
Scott recently updated its long-running Spark XC format; a bold new look and a seriously progressive and tech trail-ready ride means it has been a real hit. It’s more than accurate enough to get really aggro with too. The latest iteration also has the best Spark suspension by far, with proper chunder-calming, speed-breeding performance in its ‘Open' mode. Push the TwinLoc trigger on the bar though and you can toggle into a tauter, reduced travel ‘Traction’ mode for feisty climbs or fully lock it for sprinting, and that response is matched by the front fork, too.
Arguably the Spark shouldn't be on this list as the range-topping Spark RC SL EVO AXS model doesn't actually meet the sub 10kg criteria for this buyer's guide. We are willing to forgive that 100g though considering it has an uncompromising spec including a dropper and big tires which means you can really rally this bike to its full 120mm of travel potential.
We reviewed the Scott Spark Team Issue AXS model and were very impressed with its performance.
Cannondale is another brand that has always had racing close to its maxed-out heart and the Scalpel HT Hi-MOD 1 is a new super-light hardtail platform loaded with typically left-field features.
Most obvious is the Ocho fork, the latest version of a left-leg-only suspension family that’s now 20 years old. The cantilevered single crown carbon fork makes it the lightest Cannondale fork yet and it’s also competitively smooth once you find the set-up sweet spot. Even after a double decade on the faceted, inset needle-bearing leg technology, the tracking is still a head bender but you’ll soon learn to make the most of it on aggressive overtakes or tire ripping turns. The 50mm fork offset and short stems as standard make for fast yet confident steering despite a slack 66.5-degree head angle although the comparatively short reach (444mm on a large) will feel a little odd compared to the modern crop of longer bikes.
The Ballistec carbon frame shaves weight with a narrow shell 30mm press-fit bottom bracket and Cannondale was one of the first to adopt road bike style ‘Flat Mount’ disc brake fittings. It also uses a Cannondale-specific Ai wheel offset which you need to factor in when upgrading.
While Specialized's 8.6kg S-Works Epic AXS HT is pretty impressive, for 'just' a few more thousand dollars and an extra 1,000 or so grams you can get Specialized's S-Works Epic. A thoroughbred cross-country race bike that has seen success on the world cup race circuit to the gruelling marathon stages of the Absa Cape Epic.
The S-Works Epic has one goal in mind and that is to cover ground as fast as possible. The 9.7g weight combined with Specialized Brain suspension, a system that uses valves to differentiate between pedal forces and bump forces, means this bike is set for every type of climb from long and smooth to steep and technical. Specialized knows that what goes up fast will need to descend equally as quickly and the 67.5-degree head angle means the Epic is not losing any time on the descents.
Although the S-Works Epic is the only model of the range to tip under the 10kg mark, Specialized offers a couple of build options that all benefit from the Epic's Brain platform and are very competitive in regards to weight in their price brackets.
Canyon has grown from a small trailer-based spares ‘shop’ at German XC races to a global bike-brand superpower with an ever-increasing number of World Cup and World Championship race wins under its belt.
This top-line hardtail features a 69-degree headtube angle, 1,154mm wheelbase, and 455mm reach on a size large. It also gets a sweet exclusive paint job, and the full build comes in at 8.9 kg.
For the build kit, the bike features a SRAM XX1 Eagle AXS drivetrain and a remote-controlled RockShox SID SL fork. SRAM also provides the braes with Level Ultimates bringing the stopping power. Reynolds Blacklabel XC wheels are paired with Maxxis tires to keep you rolling.
On a budget? There are multiple other Exceed models to choose from with more wallet-friendly build kits. They feature the same frame geometry but will have different components and will be heavier.
What you need to know about the best lightweight mountain bikes
What are the lightest mountain bike frames?
When it comes to frames the big weight penalty that racers are now routinely paying is opting for a full-suspension bike rather than one of the best hardtail mountain bikes. Unless it’s a super-smooth or strength-sapping high-altitude course most of the men’s World Cup XCO field will be on a double-damped rig, and more and more women are lining up on full sus every race. They’re a lot more fun and forgiving outside the tape if you’re not a completely competition-focused rider too. That inevitably means a roughly 250g rear shock plus pivot bearings, other mounting hardware and extra frame parts piling on the weight. As a result, even the ultra-light 1,870g Scott Spark is still 900g heavier than the hardtail Scott Scale and most head-to-head, in-brand comparisons are significantly heavier. Softail bikes like Trek’s Supercaliber race bike or Moot's ultra premium Mountaineer split the difference in weight and full suspension function.
Are cross-country race bikes lighter?
Cross-country race bikes that are ridden by pros are very light as they feature specs that are either too expensive or not available to the general public. That said it's not uncommon to find brands selling premium models that are even lighter than the bikes their team riders use. That’s generally due to sponsor demands (for example, RockShox SID Ultimate SL forks are heavier than Fox 32 Step-Cast, and Shimano XTR is heavier than SRAM XX1). With no contractual obligations for consumer bikes, sometimes brands just fit cost-no-object component mixes to create a super-light show stopper you can buy off the shelf.
What is the lightest MTB in the world?
Some bikes like Orbea’s rigid forked Alma M-Ltd are lightened further than most of us would regard practical and Niner’s Air 9 RDO can be fitted with a chain tensioning eccentric bottom bracket so you can go single-speed and ditch gears altogether. Ultra-boutique brands like FRM produce complete ultra-light builds while Unno only hand-builds its Aora hardtail in a single size. If you really want to see what’s possible then click on the infamous gram hating hangout weightweenies.starbike.com. Or check out how anti-gravity artists like Gustav Gullholm (Dangerholm on Instagram) get Scott Spark and Scale bikes down to 7kg with belt sanders, paint stripper and ultra-light carbon fiber cockpit and seating combinations.
NB: We’ve had to rely on manufacturers' weights for this run down, so if you want to be sure of weights take your scales with you when you go shopping. Please contact us if any of the numbers are right off so we can update the feature for everyone else.