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The MTB fork quick reference guide

By Bruce Lin

Published

When you first get your hands on a new mountain bike, do you squish the fork a few times? Yeah, we all do it. It’s like revving a car engine. Sometimes you just can’t help it. And like a car’s engine, the fork is often the focal point of the bike. It’s a big factor in a bike’s capabilities and attitude. Most experienced riders can look at a fork on any bike and deduce how it will perform.

Mountain bike suspension fork guide The classic squish test.

Mountain biking wouldn’t be nearly as fun without the added traction, comfort, and control afforded by suspension forks (though there are some crazy rigid riders out there). If you’re interested in growing your knowledge as a mountain biker, it’s worth getting to know the different forks that are out there and what they’re designed to do.

This guide covers the most popular forks for each riding category, forks that you will find on bikes at The Pro’s Closet and out on the trail. This guide will make it easy for you to assess a a fork’s intended purpose and capabilities. If you want to upgrade your current fork or build a bike from the frame up, this guide is the perfect starting point.

Contents

Notes:

-The listed travel specs are for current model year forks only. Older models may have different travel options.
-For comparison purposes, the claimed weights are for top-of-the-line 29” models.
-The retail prices are for current model year forks and will sometimes be presented as a range covering entry-level to top-of-the-line models.

Mountain bike fork anatomy

Mountain bike fork anatomy explained parts diagram

The above diagram identifies the basic components that make up a mountain bike fork. The main focus for this guide is the stanchions. The amount of travel can be thought of as the amount of exposed stanchion. Stanchion diameter also affects weight, stiffness, and performance.

The majority of modern mountain bike forks use air springs because they are lighter and easily adjustable. A few enduro- and downhill-focused fork models like the Cane Creek Helm, MRP Ribbon, and Marzocchi Bomber Z1 provide a coil spring option.

Entry-level forks generally use less expensive dampers that provide fewer adjustments for controlling compression and rebound damping. Higher-end forks use more advanced dampers that are more responsive in rough terrain and provide more tuning options to dial in your fork. Dampers are a biggest contributor to the price difference between entry-level and high-end forks.

In many cases, forks from the same brand will use the same damper options across different models, but use different chassis to tailor the performance. For example, the Fox 34, Fox 36, and Fox 38 are all available with Fox's entry-level Grip damper, mid-level Fit4 damper, or the high-end Grip2 damper. Damper performance will be equivalent across models, but weight and stiffness will differ based on stanchion diameter.

XC race forks

Fox 32 step cast xc race forkCross-country (XC) race forks aim to minimize weight and maximize efficiency. To achieve this, cross-country forks offer minimal travel (100-120mm) and use smaller-diameter stanchions. These forks will often weigh 250-500 grams less than their trail counterparts. Many are also available with remote levers that allow you to quickly lock-out the fork for climbs and smooth sections without taking your hands off the bars.

Who it’s for: XC racers, riders who primarily ride less technical cross-country terrain, and ultra-endurance riders.

Fox 32 Step-Cast

Fox 32 step castAvailable travel: 100mm
Stanchion diameter: 32mm
Claimed weight: 1,443g (29” - Factory 32 Step-Cast Fit4)
Retail price: $659-999

The Fox 32 is named for the fork’s 32mm stanchions. In 2016, Fox introduced the 32 Step-Cast. This new Step-Cast construction reduced weight with narrower lower fork legs and a notable “step” at the bottom of the lowers to reduce material. The standard non-Step-Cast Fox 32 is still available as an entry-level, budget alternative.

RockShox SID SL

rockshox sid sl ultimateAvailable travel: 100mm
Stanchion diameter: 32mm
Claimed weight: 1,326g (29” - SID SL Ultimate Race Day)
Retail price: $599-799

The SID name has been in RockShox’s line-up since the early days of mountain biking and it has won countless cross-country races over the last two decades. It is currently RockShox’s lightest XC fork.

The SID has traditionally been offered in 100mm and 120mm versions, but for 2021 it has been split into two models — the SID SL and the SID. The SID SL is the pure XC fork. It has a new crown, steerer, stanchions, and chassis optimized for lighter weight and is only available with 100mm of travel.

Cannondale Lefty Ocho

Cannondale Lefty ocho carbonAvailable travel: 100mm
Stanchion diameter: 32mm
Claimed weight: 1,446g (29” - Ocho Carbon)
Retail price: $1,000-1,499

The Lefty is a unique XC race fork made by Cannondale. It is inverted and single-sided, with the spring and damper housed in a single fork leg. The supposed advantage of the Lefty design is a substantial increase in stiffness over its competitors without much extra weight. Leftys are only found on a few Cannondale models, but they have a cult following.

The Lefty was updated in 2018 to the Lefty Ocho, the first Lefty to use a single crown instead of a dual crown. The Lefty Ocho also has the benefit of using a standard steerer tube, so it is compatible with any standard mountain bike frame, meaning you don’t need to ride a Cannondale if you want to ride a Lefty. You will need a new front wheel though.

Other forks in this category: Manitou Machete, RockShox Reba (a budget alternative to the RockShox SID), DT Swiss F232

Trail/XC MTB forks

Fox 34 step castSome XC riders have started pushing the limits of their lightweight XC bikes on steeper and gnarlier terrain. So-called “downcountry” bikes fill the gap between pure cross-country race bikes and trail bikes. To suit these bikes, lightweight versions of trail forks have been introduced to improve performance on tough descents.

Who it’s for: Riders looking for a beefed-up XC race bike or a lightweight version of a short-travel trail bike for technical races and all-around riding.

Fox 34 Step-Cast

Fox 34 step cast factoryAvailable travel: 100mm, 110mm, 120mm
Stanchion diameter: 34mm
Claimed weight: 1,623g (29” - Factory 34 Step-Cast Fit4)
Retail price: $799-1,039

The 34 Step-Cast is lighter than the standard Fox 34 to bridge the gap between pure cross-country and heavier trail forks. Thanks to 34mm stanchions, it’s stiffer than the Fox 32, and it has a notable “step” at the bottom of the lowers to reduce material and weight.

RockShox SID

Rockshox Sid selectAvailable travel: 120mm
Stanchion diameter: 35mm
Claimed weight: 1,610g (29” - SID Ultimate Race Day)
Retail price: $699-899

As previously mentioned, the new 2021 SID is the more trail-focused of RockShox’s two XC forks. It uses a beefed-up chassis with 35mm stanchions but weighs about 300 grams less than a Pike. It is only available with 120mm of travel and was introduced as a direct competitor to the successful Fox 34 Step-Cast.

Trail forks

RockShox pike mtb trail forkTrail forks sit between lightweight cross-country forks and heavier-duty enduro forks, balancing weight, stiffness, and travel to suit the largest range of riders and terrain. These forks will be found on short- to mid-travel trail bikes that are designed to climb and descend equally well.

Who it’s for: Riders who want a versatile, mid-weight bike that can transition from cross-country rides to technical all-mountain rides with ease.

Fox 34

Fox 34 factory trail mtb forkAvailable travel: 120mm, 130mm. 140mm
Stanchion diameter: 34mm
Claimed weight: 1,790g (29” - Factory 34 Fit4)
Retail price: $749-949

The Fox 34 is named for its 34mm stanchions and it sits between the Fox 32 and the Fox 36. Since the release of the lighter Fox 34 Step-Cast, it is not commonly found in the shorter 120mm travel configuration.

RockShox Pike

Rockshox pike ultimateAvailable travel: 120mm, 130mm, 140mm, 150mm, 160mm
Stanchion diameter: 35mm
Claimed weight: 1,844g (29” - Pike Ultimate)
Retail price: $699-899

The Pike is RockShox’s most popular trail fork, sitting between the SID and the Lyrik. It uses 35mm stanchions for stiffness. As a result, it is a bit heavier but slightly stiffer than the smaller Fox 34.

Other forks in this category: Marzocchi Bomber Z2, Manitou Mattoc, Ohlins RFX 34, DVO Sapphire, RockShox Revelation (a budget alternative to the RockShox Pike)

All-mountain/enduro MTB forks

Fox 36 enduro mtb forkAll-mountain/enduro forks are built to absorb big impacts and improve traction and comfort in gnarly terrain. Forks in this category provide more suspension travel and have larger diameter stanchions to increase stiffness. As a result, they weigh more than trail forks, typically around 2,000 grams. High-end versions will also use dampers that provide a large range of adjustments, so riders can fine-tune their forks.

Who it’s for: Enduro racers and riders who frequently ride steep and gnarly terrain but still need to earn their turns.

Fox 36

Fox 36 factory shiney orangeAvailable travel: 150mm, 160mm
Stanchion diameter: 36mm
Claimed weight: 1,965g (29” - Factory 36 Grip2)
Retail price: $949-1,099

The Fox 36 is named for its 36mm stanchions. It is extremely popular with enduro racers and trail riders who want to beef up mid-travel trail bikes. 2021 models feature air bleed valves to release pressure build-up in the air spring to keep the fork feeling supple and a floating axle to eliminate any alignment issues that might lead to binding as the fork compresses. With the release of the new Fox 38, the Fox 36 is no longer available with travel greater than 160mm.

RockShox Lyrik

RockShox Lyrik ultimateAvailable travel: 150mm, 160mm, 170mm, 180mm
Stanchion diameter: 35mm
Claimed weight: 2,021g (29” - Lyrik Ultimate)
Retail price: $749-949

Though the Lyrik uses 35mm stanchions like the Pike, the stanchion walls are thicker to provide greater stiffness for downhill performance comparable to the Fox 36. There is overlap in travel with the Zeb, so bike manufacturers and customers can choose between the two based on how they value stiffness or weight.

Cane Creek Helm

Cane Creek Helm forkAvailable travel: 130mm, 140mm, 150mm, 160mm
Stanchion diameter: 35mm
Claimed weight: 2,080g (29” - Helm Air)
Retail price: $899

The Helm is a highly adjustable fork available with either an air spring or coil spring with internally adjustable travel. There is no budget version and it is only available with Cane Creek’s tunable damper that provides high- and low-speed compression and rebound damping adjustment.

DVO Diamond D1

DVO Diamond D1 mtb forkAvailable travel: 130mm, 140mm, 150mm, 160mm
Stanchion diameter: 35mm
Claimed weight: 2,150g (29” - Diamond D1)
Retail price: $999

DVO has become a popular alternative to established brands like Fox and RockShox. The Diamond has internally adjustable travel and uses a unique “Off the top” spring to control how supple the fork feels at the start of its travel, regardless of air pressure.

Other forks in this category: Marzocchi Bomber Z1 (air or coil), MRP Ribbon (air or coil), Ohlins RFX 36, DT Swiss F535, DVO Beryl (a budget alternative to the DVO Diamond), RockShox Yari (a budget alternative to the RockShox Lyrik)

Enduro/downhill MTB forks

Richie Rude fox 38 enduro mtb forkRichie Rude winning the EWS Trophey of Nations on the Fox 38. Photo courtesy of Yeti Cycles.

This new generation of forks pushes enduro bikes to the extreme in terms of downhill performance. They still are built with a single crown (full downhill forks will use a dual crown for maximum stiffness) but stiffness is not a concern thanks to massive stanchions. Naturally, that makes these models heavier than all-mountain/enduro forks.

Who it’s for: Enduro racers and downhill bike park riders who ride the most challenging terrain and prioritize downhill performance above all else.

Fox 38

Available travel: 160mm, 170mm, 180mm
Stanchion diameter: 38mm
Claimed weight: 2,180g (29”)
Retail price: $949-1,199

The Fox 38 is Fox's latest long-travel single crown fork for enduro riding. Along with thick 38mm stanchions, it also uses a new elliptical inner-shaped steerer tube to increase stiffness and a new chassis with a round arch. Like the new 36, the 38 features air bleed valves to release pressure build-up in the air spring and keep the fork feeling supple and a floating axle.

RockShox Zeb

RockShox Zeb enduro mtb forkAvailable travel: 150mm, 160mm, 170mm, 180mm, 190mm
Stanchion diameter: 38mm
Claimed weight: 2,265g (29”)
Retail price: $699-999

The Zeb is RockShox's latest long-travel single crown fork for enduro applications. RockShox claims it’s 21% stiffer torsionally than the Lyrik — a very significant amount. Fore-aft stiffness, however, is only increased 2% to keep handlebar feedback low to maintain comfort. There is overlap in travel with the Zeb and Lyrik, so bike manufacturers and customers can choose between the two based on stiffness and weight preferences.

Other forks in this category: Manitou Mezzer, DVO Onyx SC-D1, Ohlins RFX 38

Additional reading:

The two most prominent fork manufacturers are Fox Racing Shox and RockShox. If you’d like to learn more about their fork offerings, check out our in-depth Fox vs. RockShox article. It covers technology, features, popularity, race results, and the hierarchy within their fork models.

Forks come in different offsets which will affect your bike’s handling. If you’d like to learn more about the mysteries of fork offset, check out our article: “What is fork offset?

 

What forks did we miss? What’s your fork of choice? And what fork do you want to try on your next mountain bike? Let us know in the comments!


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