Cannondale Synapse Carbon 105 Review
The Cannondale Synapse Carbon 105 is an endurance bike with workhorse capabilities and quality specs at an affordable price point.
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- Comfy full carbon frameset
- Hydraulic brakes
- Complete Shimano 105 groupset
- Nimble handling for an endurance bike
User Review
The Synapse 105 is an endurance bike that enables you to train longer and harder with its upright geometry and dependable componentry. The model is different enough from a pure road model to offer extra comfort while still delivering on race pace. This mid-tier model has all the touches carbon lovers and budget-conscious riders want, and forgoes the blingy touches you don’t need on extended training rides.
To get the most out of the carbon frame and Shimano 105 groupset, though, you might want to upgrade the wheels to a lighter pair.
Part of the popular Synapse range
Since its debut in 2005, Cannondale’s Synapse range has proven itself a dependable and quality option for high-mileage riders and adventurous roadies. The innovative brand introduced the Synapse line long before ‘endurance bikes’ was a well-defined category. Receiving upgrades every few years, the Synapse models have stood the test of time and are now some of the most popular endurance bikes.
The 2021 Synapse 105 is built around a full carbon frameset with upright geometry designed for comfort on long rides without sacrificing performance. The carbon fork and frame are made from Cannondale’s proprietary BallisTec lightweight carbon construction.
Cannondale also utilizes their SAVE micro-suspension technology with advanced tube shapes to add a bit of comfort over the bumps and road buzz. This clever tech can save your butt (literally) and back when out on extended training rides and need a smoother ride on less-than-perfect road surfaces.
Traditional frame shape
This model achieves a more relaxed rider position by having a relatively tall stack height and high front end. The setup can feel odd for riders that want a more aggressive position but does well to avoid straining your back on longer rides. Cannondale decided not to extend the wheelbase on this endurance model, a change that adds stability but removes some responsiveness.
Therefore, with the wheelbase the same as Cannondale’s Supersix road model, the Synapse is plenty confident on speedy descents and preserves its playful handling.
The carbon frame offers more relaxed road bike geometry but isn’t anything special, receiving its last update in 2017. This year, the Synapse range got its long-overdue redesign and included a frame change and SmartSense radar system. The reimagined models are enticing but come with a significant price jump compared to this era of Synapse.
Lefty history
The Lefty story begins with a suspension product that plenty of vintage mountain bike nerds will know: the HeadShok.
In the early ‘90s, mountain bike suspension was emerging. The first forks lacked stiffness, which compromised control. Cannondale sought to fix that problem with the HeadShok. Introduced in 1992, this new design moved the spring and damper away from the fork legs to inside the head tube and provided 50mm of travel.
Even back in the ‘90s, Cannondale employed a key design feature that would find its way into the Lefty: needle bearings. Instead of bushings used in other forks, the HeadShok rode on four strips of needle bearings sandwiched between the inner and outer tubes, keeping stiction to a minimum.
As riders demanded more travel, Cannondale moved the technology outside of the head tube and created the downhill-oriented Moto fork in 1996. The Moto was essentially a dual-crown fork made up of two HeadShoks mounted on each side. The fork went through several iterations that provided 100-120mm of travel. The most famous version was the Moto DH fork found on the legendary Fulcrum downhill bike.
Soon, Cannondale engineers began experimenting to create a lighter version of the Moto fork for XC and trail riding. They realized the simplest solution was to rely on the Moto’s extremely stiff design and essentially chop the fork in half. The Lefty was born, officially launching in 1999.
The Lefty has taken many forms over the last 20 years but was primarily an XC fork with 100-120mm of travel. Recently, the Lefty Supermax provided longer-travel versions for trail and enduro bikes with 130mm-160mm of travel, and the Lefty Olaf was made specifically for fat bikes. In 2015, the Lefty Oliver was introduced as the first production suspension fork for gravel riding. It was found on the Slate gravel bike and provided 30mm of travel.
Cannondale’s latest Lefty, the Lefty Ocho, is a cross-country fork with 100-120mm of travel. It is a huge leap forward, packing all of that technology into a single-crown design. Unlike its dual-crown predecessors, the Ocho uses a conventional tapered steerer, compatible with any modern frame. It’s currently found on the F-Si hardtail and Scalpel full-suspension XC bikes. It is also the basis for the second-generation Lefty Oliver on the Topstone Lefty gravel bike.
Brazilian Champion, Henrique Avancini on the Lefty Ocho | Photo: Bartek Wolinski/Red Bull Content Pool
Over the years, the Lefty had great racing successes. Italian Marco Fontana won a bronze medal at the 2012 London Olympics (where he finished without a saddle!). Henrique Avancini won XCO and XCC races in the 2020 UCI Mountain Bike World Cup, and multiple riders won Unbound Gravel titles aboard Cannondale Slates equipped with the Lefty Oliver.
Lefty technology
The Lefty fork consolidates all the components of a conventional fork into a package that’s essentially half the size. To accomplish this, Cannondale used clever engineering to help the Lefty match and even exceed the performance of conventional XC forks.
Keyed stanchion
Note the flat sides in the upper part of this Lefty Ocho stanchion | Photo: Cannondale.
If you’ve ever played with a rear shock that’s been removed from a bike, you’ll notice that it’s easy to rotate the shaft within the body of the shock. This is because the shock is essentially a cylinder within a cylinder. This is also true of a conventional fork leg. Obviously, rotation is undesirable because the front wheel has to stay aligned with your handlebars to maintain control. To prevent twisting, forks need to be “keyed.” For conventional forks, this is handled by the fork arch and axle that tie the lowers together and prevent them from rotating independently.
Because the Lefty is single-sided, there’s no fork arch or axle with two fixed sides. Instead, it uses a design feature from the first HeadShok. The stanchion itself acts as a key. The upper portion of the stanchion has four flat sides that slide into a tube with matching flat sides to prevent the shaft from twisting. Rather than a conventional cylinder-in-cylinder design, the Lefty is square-in-square. The one exception is the new Lefty Ocho which is three-sided, but more on that later.
A keyed stanchion has a couple of benefits. First, the shape of the tube provides greater fore-aft and torsional stiffness than the round tubes used on conventional forks of the same travel and weight. This stiffness reduces front-wheel deflection and improves steering precision and control in rough terrain. Second, the flat sides allow a Lefty fork to use needle bearings instead of bushings.
Needle bearings
Strips of needle bearings used on the flat sides. In the new Lefty Ocho, the three-sided bearing strip is called the Delta Cage. | Photo: Cannondale.
Needle bearings are a type of roller bearing with long, thin cylindrical rollers resembling needles. Compared to ball bearings and ordinary roller bearings, needle bearings have more surface area in contact with the races, so they can support high loads like those experienced by a suspension fork. A Lefty moves on thin strips of needle bearings that are placed on each flat side of the inner tube.
Conventional forks with round tubes move on bushings, which are essentially plastic rings. Bushings have more “stiction,” or static friction that needs to be overcome before the fork moves into its travel. Compared to bushings, needle bearings feel nearly frictionless and allow the Lefty to quickly and easily move into its travel.
Bushings can also bind when the tubes flex from torsional forces. Needle bearings, however, aren’t affected by this. In a Lefty, the vertical movement of the fork is separated from other forces because the bearings can still spin and move as the fork flexes, allowing it to continue responding to the terrain.
Upside-down design
A Red Bull MotoGP Rookies Cup KTM with an inverted or USD fork. Note the stanchions are at the bottom. | Photo: Gold Goose/Red Bull Content Pool.
For years, high-performance motorcycles used inverted or upside-down (USD) forks, with the stanchions at the bottom. Because upside-down forks are thicker and stiffer at the head tube, where leverage is greatest, they perform better under hard braking and cornering.
Many manufacturers attempted to bring upside-down forks to mountain biking but most products have been short-lived. The discontinued RockShox RS-1 is a good example, and before that, Manitou’s Dorado, Maverick’s Duc, and Marzocchi’s Shiver, to name only a few. Manufacturers were never able to strike a balance between stiffness with weight. Plus, upside-down forks often required proprietary hubs. Due to its low weight and Cannondale’s continued commitment to the design, the Lefty has been the most successful upside-down mountain bike fork to date.
The Lefty Ocho
The Lefty Ocho was released in 2018 and is the eighth (hence the name) iteration of the Lefty fork. It has a few key design improvements that made it the best-performing Lefty yet.
Lefty forks: Pros
Greater rigidity and reduced stiction
The tube shapes and upside-down design contribute to the greater overall stiffness. Needle bearings reduce stiction compared to bushings and eliminate bushing bind when bending and twisting forces are applied to the fork.
Compared to a conventional fork of the same travel, the stiffer Lefty should provide more precision, control, and active suppleness in rough terrain, or under hard braking and cornering.
These performance benefits can be seen in this demonstration by Beukers Bike Centre below:
The impressive rigidity of the Lefty chassis is clear when the presenter is able to lean his full weight on the fork without substantial flex. With a wheel mounted, the demonstration shows that torsional forces applied to the wheel (like you’d experience riding through a rock garden or a fast corner) have a great effect on the conventional fork’s ability to move, while the Lefty still compresses freely.
Of course, this demo was put on at a Cannondale dealer by a Cannondale representative so it should be taken with a grain of salt. It’s also over 10 years old and features forks that are no longer in production. But the key differences shown in this video are still applicable to forks produced today.
Also, watch Pinkbike’s “28 Bikes Bottomed Out In Ultra Slo Mo (1000 FPS)” video. Viewed in slow motion, the Lefty Ocho visibly flexes less than its competitors, the Fox 32 Step-Cast and the RockShox SID. It even appears stiffer than several heavier trail forks like the Fox 34 and RockShox Pike. It’s not scientific, but it supports the Lefty’s claim to superior rigidity.
The Lefty is more than light enough for World Cup XC racers. The stiffness helps Henrique Avancini navigate this gnarly rock garden. | Photo: Bartek Wolinski/Red Bull Content Pool.
Lighter weight
This increased rigidity comes without a significant increase in weight. Through the years, the Lefty has remained competitive with the lightest XC forks. The current Lefty Ocho carbon has a claimed weight of 1,446 grams which makes it comparable to the Fox 32 Step-Cast (1,443 grams) and the SID SL Ultimate (1,326 grams) while having stiffness comparable to heavier, more trail-oriented forks like the Fox 34 Step-Cast (1,623 grams) and the 35mm stanchion RockShox SID Ultimate (1,610 grams).
Easy tire removal
Given it’s only one-sided, it’s possible to change a flat without removing the front wheel — there’s no right fork leg in the way. This can make changing tires or performing trail-side puncture repair slightly easier. It’s not a big deal given the prevalence of tubeless and tire repair plugs, but a fun party trick nonetheless.
FILLING A NEED FOR GRAVEL SPEED
Cannondale’s SuperSix Evo gets a facelift
Cannondale’s legendary SuperSix Evo is no longer the super-light climbing bike that it was once known for being. Cannondale took the name of their well-known SuperSix Evo road bike and created a gravel bike, the SE, with nearly none of the characteristics of its namesake.
Much like the rest of the road bike market, the original SuperSix Evo underwent compliance-focused design cues to appeal to a wider assortment of riders and ride types. Now in a similar fashion, Cannondale is optimizing its former dedicated cyclocross bike, the SuperX, to appeal to the competitive gravel rider.
THE FRAME
The Supersix Evo SE frame owes much of its geometry to Cannondale’s SuperX cyclocross bike. Our size-54 SE has a relatively short 102mm wheelbase. This is achieved by 422mm chainstays and Cannondale’s Asymmetric Integration. Cannondale’s AI offsets the rear triangle and requires the rear wheel to be dished 6mm to the right. This affects the angle of the chainline as well; but most importantly, it allows for more tire clearance.
“The SuperSix Evo SE responds quick to rider inputs and rides like a cyclocross bike, but with the added versatility of wide tires.”
Cannondale’s original gravel bike, the Topstone, was held back by a maximum tire clearance of 40mm; the new SE can fit up to 45mm tires. In addition to the wheelbase and chainstay length, the Cannondale SE shares the same 55.5cm stack, 37.8cm reach and 71-degree head tube angle as the SuperX.
Cannondale pulled similar airfoil tube shapes from the latest iteration of the SuperSix Evo road bike for use on the SE. The SE has a claimed frame weight of 1000 grams in a size 56. Like any proper road bike there are just two bottle mounts, but wait, we thought this was a gravel bike?!
We’re fans of the refreshingly simple Cool Mint colorway, but would like to see some flashier colors added alongside the other Meteor Gray option.
THE PARTS
We were a bit surprised to find SRAM’s Rival AXS group on the 5000 build. Rival ranks the lowest on SRAM’s three-tier wireless AXS platform but includes much of the same shift performance as the higher-end Red and Force groups. What sets Rival components apart from the higher-end siblings is its weight, which scales in at nearly a pound and a half heavier than the Red AXS series.
The SE’s 46/33 chainrings can be found in either of SRAM’s other offerings and the choice to use the Rival left us desiring some weight savings since Cannondale is marketing the SE as a gravel “race” bike.
Our bike hit the scales at a hefty 19.12 pounds. A positive with the Rival spec is the hard-to-find 10-36 cassette, which isn’t offered in Red AXS but is available in Force. We also prefer the minimalistic hood design. They lack the ports for satellite shifters, making it significantly smaller and easier to wrap one’s hands around.
A pair of DT Swiss CR 1600 tubeless-ready rims were laced with 24 DT Swiss Aero Comp straight-pull spokes to DT Swiss 350 hubs. The rear wheel is offset to account for the 6mm Asymmetric Integration frame design mentioned earlier. This is a bit of a hindrance for anyone planning to swap wheels. In order to use another wheelset, it would require the same offset dishing. For most people, it’s going to be more expensive to build a new set of wheels specifically for the SE, which is especially complicated in our world of pre-built wheels.
Our test bike shipped with 38mm Vittoria Terreno tires. Cannondale says they are planning to use 40mm on future orders. We were impressed with the overall tire and debris clearance for a performance-oriented gravel frame.
Starting up front, small parts include Cannondale’s 6061 alloy bar and stem with a Hollowgram SL Knot carbon seatpost with 15 degrees of setback and a Prologo Dimension AGX saddle providing seating capabilities.
THE RIDE
Given its nearly identical geometry to the SuperX, the SuperSix Evo SE responds quick to rider inputs and rides like a cyclocross bike but with the added versatility of wide tires. However, the geometry and road-bike-like tube shapes provide an aggressive, stiff approach to gravel. It feels at home on technical singletrack, thanks to its short wheelbase and steep head tube angle, but we could feel just about every rut more than usual.
The SRAM Rival AXS drivetrain offers a less than one-to-one gear ratio with its 46/33 cranks and 10-36 cassette, which is appropriate for climbing in steeper off-road conditions. On the flats, we found ourselves in the big chainring, usually in the middle of the cassette. It was rare we made the jump into the 10-tooth cog, but it was nice to have it for long road descents.
The braking on SRAM Rival is sub-par when compared to the Red AXS and Shimano GRX builds. Modulation is spongy, and the brakes lack the bite of their Shimano counterparts with less power than other options.
We were pleased that Cannondale has released a frame with clearance for up to 45mm tires. The Topstone left us yearning for more pneumatic cushion on the already compliant frame. Given the relative stiffness of the SE, the wider tire clearance adds much-needed utility.
The best gravel bikes in 2023 | Top-rated carbon, aluminium, titanium and steel gravel bikes reviewed
If you’re looking for an objective assessment of the best gravel bikes on sale in 2023 then you’ve come to the right place. All of the bikes in this article have been ridden and rated by BikeRadar’s expert testers.
Gravel and all-road are terms used for this rapidly growing segment of the drop-bar bike market. These bikes have generous tyre clearances and gravel-specific geometry that is typically more stable and forgiving than traditional road bike geometry. Modern gravel bikes were born out of the American Midwest, where gravel racing took hold a decade ago and has gained popularity steadily.
- Carbon gravel bikes offer low weights and balance stiffness and compliance
- Aluminium gravel bikes are often the most affordable option
- Titanium gravel bikes are incredibly desirable and often considered ‘forever bikes’
- Steel gravel bikes have a classic feel and tend to be favoured by bikepackers
You can also skip to our buyer’s guide to gravel bikes, which explains everything you need to know about these practical, versatile and fun bikes.
Best gravel bikes in 2023
Best carbon gravel bikes
Carbon fibre gravel bikes are lightweight, stiff and are designed to absorb vibrations effectively.
Carbon fibre’s pliancy will do a lot of work to minimise any chatter from the surface beneath while still letting you put a lot of power through the cranks.
Many gravel race bikes are made from carbon, but there are plenty of carbon gravel bikes tailored to bikepacking and more technical riding.
Below is a selection of carbon gravel bikes we have tested that encompasses most of the above. Head to our full buyer’s guide to the best carbon gravel bikes for a complete rundown of every model we have tested.
Canyon Grizl CF SL 8 1by
The Canyon Grizl is handsome looking with all the mounts you could dream of for fenders, bottles and bags. Matthew Loveridge / Immediate Media
- £2,949/5000,849/€2,699/AU4,249 as tested
- Pros: Versatile carbon frameset; great spec; well thought out geometry
- Cons: Gearing might not be low enough for some; Canyon-specific mudguard mounts
The Canyon Grizl is a burlier version of the Canyon Grail, which is also one of the best gravel bikes. The Grizl has clearance for 50mm tyres, mounts for fenders and bags, and long geometry – all working together to make it an ultra-versatile bike.
The bike has a good value-for-money spec, with a Shimano GRX groupset, DT Swiss wheels, a Canyon VCLS leaf-spring seatpost and a Fizik Terra Argo saddle.
The Grizl is happy on tarmac, but really shines off-road, especially on dirt trails and gravel singletrack.
The 1x drivetrain might not be the desired choice for all, but there are 2x Grizls in Canyon’s range.
One drawback with this bike is the mudguard mounts are specific to Canyon.
Giant Revolt Advanced Pro 0
The Giant Revolt Advanced Pro 0 features the brand’s new fork and frame. Russell Burton / Our Media
- £4,999/6,400/€5,599/AU6,699 as tested
- Pros: Thrilling and plush ride; great groupset; fast wheels
- Cons: Tyres aren’t suited to wet or muddy terrain
The Giant Revolt Advanced Pro 0 is our Bike of the Year for 2022, the first time a gravel bike has won overall. Equipped with Shimano’s GRX Di2 2x groupset, the Revolt’s shifting and braking is pretty much flawless.
The build weight of 8.3kg doesn’t suggest sprightliness, but Giant’s lightweight CRX wheels and sharper geometry make the Revolt spry on- and off-road.
The new fork permits the Revolt to run tyres up to 53mm wide.
The Revolt also has plenty of mounts and bosses to carry luggage on bikepacking trips.
The Giant Revolt X Advanced Pro 1 is similar to the Advanced Pro 0, but it has a gravel suspension fork for more technical riding.
Latest deals
Liv Devote Advanced Pro
The Liv Devote Advanced Pro is the first women’s-specific gravel bike from Liv. Phil Hall / Immediate Media
- £4,699/5,500/€5,000/AU7,299 as tested
- Pros: Women’s-specific geometry; dropper seatpost compatibility
- Cons: Tyres are sketchy in the wet
The Liv Devote Advanced Pro is the brand’s first gravel bike and one of the best women’s gravel bikes.
As with the rest of the Liv range, the frame’s geometry/sizing and carbon layup have been chosen specifically with female riders in mind.
The shock-absorbing seatpost is very effective at reducing trail buzz. The bike will also accept a dropper post should you want to maximise the bike’s handling on descents.
It’s a bike that is supremely comfortable over long distances and has mounts for mudguards, luggage, bottles and accessories, so it’s ready for as much adventure as you can take on.
Latest deals
Trek Checkpoint SL6 eTap
- £3,850/4,300/€4,300/AU5,500 as tested
- Pros: Comfy and fairly fast; mounting options; excellent handlebars
- Cons: Can be rattly
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What is a gravel bike?
A gravel bike is a drop-bar bike designed to be ridden on a wide variety of surfaces and not just gravel – even if this is where gravel riding did originate.
The best gravel bikes look a lot like traditional road bikes, but there are four key features that usually distinguish them.
Wider tyres
First and foremost, gravel bikes have wider tyres. Since these bicycles are designed to traverse miles of unpaved roads, their tyres are substantially larger. Likewise, mud clearance is also a concern in these conditions.
Tyre widths range anywhere from 30mm to 48mm. In addition to 700c wheels, it is also common to see smaller-diameter 650b wheels used with higher-volume tyres. Many of the best gravel bike tyres feature a fast-rolling centre tread with knurling or side knobs to improve cornering ability on mixed surfaces.
Tubeless tyres are also commonly found on gravel bikes because the latex tubeless sealant provides a degree of insurance against punctures.
Geometry
Given the terrain gravel bikes are expected to cover, frame geometry often rests somewhere between road bikes and cross-country mountain bikes. Russell Burton / Immediate Media
In addition to wider tyres, gravel bikes have geometry that favours stability and comfort.
The best gravel bikes have a longer wheelbase than most road bikes thanks to longer chainstays and slacker head-tube angles.
Head tubes are generally taller as well, placing the rider in a more relaxed, upright position. Bottom brackets are often lower, which gives the rider the sensation of riding in, rather than on the bicycle.
The end result of these geometry differences is a more comfortable, confidence-inspiring and forgiving ride than you would find in a typical road bike.
The best women’s gravel bikes follow the same principles in terms of geometry but are often tailored to better suit women riders.
Frame features
Gravel bikes often have mounting points for bags on the frame and even on the fork legs. Russell Burton / Immediate Media
Another thing you’ll usually find on gravel bikes that road bikes don’t have is extra mounting points for luggage. That allows them to be used for bikepacking or just lets you add a third water bottle for long rides in the outback where water sources may be scarce. Likewise, there are often mounts on the top tube for a feed bag.
Gravel bikes also usually have mounts for a rack and mudguards/fenders, so they can do double duty as poor weather road bikes.
There’s a newer category of gravel race bikes though, like the Pinarello Grevil F and the Cervélo Áspero, which abandon their bikepacking pretensions and just have a fairly standard set of road-type mounts, maybe with extra bottle cage bosses under the down tube. They’ll have a more racy geometry, more like a road bike, and often include aero features and tube profiles.
Handlebars and stem
Gravel bikes typically have a shorter stem and wider handlebars than road-going drop bar bikes. That mirrors mountain bike geometry and leads to a bike that’s more easily manoeuvred over variable terrain.
The handlebars usually have a flare to them, where they widen out from the tops to the drops. That gives you more control when descending in the drops. It also means that if you decide to fit a bar bag, there’s more space to grab the drops without the bag getting in the way.
Gearing
Gearing is another area where gravel bikes diverge from the pack.
The rise of gravel bikes has, in turn, been accompanied by the arrival of gravel-specific groupsets. While early gravel bikes might have featured road bike groupsets with compact cranksets, the latest gravel groupsets – including Shimano GRX, Campagnolo Ekar and SRAM XPLR – provide a more suitable and forgiving selection of gears.