Cannondale has always been a revolutionary brand when it comes to bicycle technology. Its single-arm Lefty fork is the best example of the innovative policy that the American brand has always showcased. This suspension fork, far from the classic two-bar chassis model, is primarily designed to deliver a front suspension with the best balance between absorption, stiffness, and weight. In addition to being a highly versatile suspension fork, the Lefty fork offers benefits that go beyond its stiffness and lightness, such as smoothness, quick response, and customization options. That doesn’t mean that Cannondale’s fork is the ultimate one, as it also has some drawbacks, mainly due to its greater mechanical complexity. Here we list both the advantages and disadvantages of this striking mountain bike fork, which provokes equal parts love and hate.
History of the Lefty fork
It’s worth reviewing the origin and development of the Lefty fork to better understand the purpose for which it was created and the improvements it has received over more than 20 years of history. Cannondale was one of the brands that provided the greatest solutions for mountain bike suspension in the nineties. In 1992, it introduced the Headshock, a unique front suspension system based on a shock absorber installed between the head tube and the rigid fork. This shock absorber slid along the tube using four metal, rectangular strips with needle bearings, which significantly reduced internal friction to achieve a very smooth suspension operation. This was the system that inspired Cannondale seven years later to create its single-arm fork. Why only one? Because the brand’s engineers wanted to continue taking advantage of the effectiveness and smoothness of the Headshock in the fork itself, but that would mean using two Headshocks, one for each stanchion, adding extra weight that would hamper performance. Therefore, starting from the design of its Moto downhill fork and using the double crown structure—which had already been used in motorcycles—Cannondale “split” the fork in two. They kept only the left arm to reduce weight while still using the Headshock system. Thus, the Lefty was born (its name refers to that left arm) in 1999.
Technological evolution: from the double crown to the single-crown Lefty 8
Legendary models such as the Scalpel, Jekyll or F-Si have come standard with this fork. Its famous arm has also received improvements regarding weight and stiffness. Barely two years after its launch in 1999, the first Lefty with a carbon stanchion was commercialized, also inverting the position of the stanchion with respect to the leg, with the former now sitting underneath. In 2010, the crown was welded to the fork arm in the aluminum version, thanks to OPI (One Piece Integration) technology. This solution gave the front end more lightness, greater stiffness, and increased steering precision. And from there, it evolved to the latest major Lefty breakthrough: the launch of the model 8 (8th generation) in 2018. A revolutionary Lefty fork, with 100 or 120 mm (depending on the version), which for the first time dispensed with the double crown and the attachment to the head tube was like that of any other conventional fork. This opened up the possibilities for mounting the Lefty on other bikes that were not Cannondale.
Advantages of Lefty forks
Beyond the striking aesthetics that a Lefty fork brings to a mountain bike, the truth is that this type of single-arm suspension provides some advantages, among which we highlight the following:
Greater sensitivity
The sliding of the stanchion through needle bearings and not by friction bushings, as in other forks, gives the Lefty greater initial sensitivity. Also, because the stanchion is located closer to the wheel axle. That is, when riding with it over rocky terrain, close and successive obstacles, the suspension reaction is immediate and it quickly returns to its initial position.
Great smoothness
This friction through needle bearings provides better sliding of the stanchion. Greater smoothness is synonymous with better response, faster recovery of travel, and greater control of the bike on technical trails.
Balance between weight and stiffness
One of the drawbacks of the previous Lefty fork, the double crown one, is that in the years immediately preceding the appearance of version 8, it was already at a disadvantage if we compared its weight with the new Fox 32 and RockShox SID for XC. By eliminating the double crown, the Lefty has saved 250 grams on the scale and has a very similar weight (1,446 g without lockout lever) to these competing forks. Likewise, having a stanchion with straight internal sections, instead of circular, provides extra stiffness in several directions: vertical, torsional, etc., which improves the rider's pedaling efficiency (avoiding power transmission losses due to suspension movement) and the overall maneuverability of the bike.
Adjustments and compatibilities
The mounting compatibility with any tapered head tube of any mountain bike frame has definitely opened up the market for the Lefty beyond Cannondale. In addition, it has the same or even more compression or rebound adjustments as other forks, and spacers can be introduced to reduce the air chamber volume. It is worth mentioning here that the single arm of the fork houses both the air chamber and the hydraulic cartridge, which in conventional forks are separated and installed one in each arm. Furthermore, the Lefty 8 is available for both 29" and 27.5" wheels (the latter only in the aluminum option).
Disadvantages of the Lefty 8
Obviously, not everything is perfect with Lefty forks, which still have room for improvement in certain aspects. We highlight the following:
Need for a specific hub
Although it is now possible to install the Lefty on any mountain bike frame with a tapered head tube, it should be clarified that it requires a specific wheel hub. This means an extra expense to adapt the wheel to the fork.
Slower wheel installation and removal
In previous versions of the Lefty (2.0, OPI, etc.), installing and removing the wheel could be somewhat troublesome, as it was also necessary to remove the brake caliper. In the Lefty 8, this problem has been improved by incorporating an eccentric release bolt on the StopLock caliper mount, of the PostMount type. By turning the bolt 180º with a 5 mm Allen key, the caliper is quickly released, allowing the wheel to be removed laterally. However, removal is still done in two phases: first remove the caliper and then loosen the axle fixing bolt (also requiring an Allen key). Thus, the operation remains somewhat slower than removing the axle, as is typical with other forks.
Fewer available service centers
The Lefty fork, even after improving its compatibility beyond Cannondale bikes, remains an exclusive product with a specific operation. This is why its maintenance must inevitably be carried out at Lefty service centers. And this network of workshops is not as widespread or as extensive as those of the major suspension brands. Nevertheless, and regardless of its exclusivity, the maintenance intervals are very similar to those of its competitors on the market. The Lefty fork should go through technical service at least once a year for a basic inspection (seals, oil, and cartridge check), with a cost that the brand sets at 100 euros.
Should I switch my fork for a Lefty?
Possibly, after reading this article, you might ask yourself this question. If your frame is compatible with the Lefty 8, even if it is not from Cannondale, and you want to have a high-quality, lightweight, and fast-responding short-travel fork, you should seriously consider making the switch. The price of the Lefty fork can be a barrier (1,599 euros for the carbon version), as well as the need for a specific hub for its installation. However, Cannondale offers an aluminum version that is 500 euros cheaper (1,099 euros), making it price-competitive with the rest of the high-end XC forks on the market.
Additionally, in 2016 Cannondale launched a variant of the Lefty for gravel, the Oliver, with 30 mm of travel, and which has recently adopted the 8's design with the same compatibilities. Lastly, take into account your level as a biker and the type of routes you do if you want to get the most out of the Lefty. It is a fork created initially for competition and to adapt to highly demanding XC routes both physically and technically. If you only use your MTB for fun or to do occasional rides, it might be better to opt for a less exclusive and more conventional fork that is more suited to a more recreational type of mountain biking.