First Point Of Contact

Your local bike shop or bicycle manufactuer should be the first place to source information when considering a shock upgrade. They can offer valuable insights into which shocks are compatible with your bike model as well as what the eye-to-eye and stroke lengths are to prevent any compatibility issues down the road.

Some brands will even go one step further and suggest suspension settings such as spring rate (air and coil), Compression, and Rebound settings. If you cannot get information from the manufacturer, we have a host of checks and measurements below.

If there is no specific information about which rear shocks will fit, there are a few things to consider before deciding on a new shock.

You've got a choice to make—an inline or reservoir shock

Alright, folks, imagine your mountain bike sitting in the garage, it's a dual suspension and you're looking at upgrading your shock. You've got a choice to make - a inline shock or a reservoir shock. What's the deal, and why should you care?

Inline Shocks:

Think of inline shocks like the ninja of mountain bike suspension—sleek, stealthy, and ready to rock. These bad boys are compact and take up the least amount of space in your frame. They're the go-to choice for XC (cross-country) or trail riders who want a lightweight and efficient shock but you will see these shocks on all kinds of bikes, up to enduro rigs.

Picture it this way: Inline shocks are like a hidden dagger. They are a compact package that delivers precise performance when you need it most. Perfect for those who want to climb like a mountain goat and descend like a downhill daredevil, all while keeping things lean and mean.

Reservoir Shocks:

Now, let's talk about reservoir shocks. These are the rockstars of the mountain biking world. Imagine a shock with an extra, well, "reservoir" canister attached to it. It's like strapping a nitrous oxide tank onto your bike – extra power, extra show!

Reservoir shocks are all about soaking up the big hits with style. When you're bombing down steep descents or launching off monster jumps, the extra oil volume and cooling capacity in that reservoir canister keep your shock cool and collected. It's like having an extra set of lungs to help you scream down the trail without breaking a sweat.

So, inline vs. reservoir?

It's all about the terrain and your riding style. If you're into long climbs and want to save energy, go inline. If you live for the adrenaline rush and demand top-notch performance on those epic descents, then it's time to reservoir your way to glory.

In the end, it's not about being better or worse; it's about choosing the shock that matches your biking mojo. Inline for precision, reservoir for power – the choice is yours, you two-wheeled trailblazers!

Space In Your Frame

The first thing to consider is the style of rear shock you want or need for your frame: an in-line air shock, an in-line coil shock, or a reservoir-style system.

Switching from an in-line shock to a reservoir style system, like swapping a Deluxe to a Super Deluxe, requires some careful consideration. To assess compatibility, you can release air pressure from your current shock and cycle the suspension. While doing this, pay attention to any potential interference between the shock and objects on the frame, such as water bottles, cages, spare straps, or tubes. The available space around the shock can vary significantly depending on the bike model, as shown in the examples below. This step ensures that the new shock's reservoir design won't face any obstructions during suspension movement. 

Shock Measurements, Explained

There are a few key measurements that you will need to know to determine the correct fit for you. These measurements include eye-to-eye, stroke, and mounting hardware.' The best course of action is to visit the manufacturer's website, consult your local bike shop, directly contact the manufacturer for guidance, or measure this yourself. If you are measuring it yourself, please make sure you have an accurate measuring device like digital calipers/verniers, as the stroke lengths change by 2.5mm, which is quite a small margin.

What Is Eye-to-Eye?

The eye-to-eye measurement refers to the total length of the shock from one mounting bolt to the other. It's a critical factor for proper fit and bike performance. Using a shock that is too long or too short can result in irreparable damage to your bike while also significantly altering its geometry. It's essential to ensure the shock's eye-to-eye measurement matches your bike's specifications.

To measure this yourself, take the measurement from the center of the shock mounting points, as illustrated below.

What Is Stroke Length? 

The stroke length differs from the bike's overall travel due to linkages and rear wheel travel, which is measured from the rear axle. For the latest 'metric' shock sizing, each eye-to-eye length generally has four stroke length options. It's crucial to use the stroke length specified by your bike manufacturer.

Friends don't let friends overstroke their shock. (Unless your bicycle manufacturer states you can.)

Changing the stroke of your shock may sound or seem like you are just getting secret extra travel for your bike and in a sense you may. But there are a huge amount of factors and concerns that come into play if you are using a stroke length that is longer than intended for your bicycle, which, at a minimum, can void any warranty you have on your bike, and can even cause serious injury or death for riders. Factors that can cause damage may extend to dynamic riding situations as opposed to clearance issues you can see in the workshop, these include but are not limited to:

1. Contact between the wheel and seat stay. This can even occur under flex of the frame under High Compression situations. 
2. Linkages over-rotate, damaging frames or becoming stuck.
3. Excess force put onto linkages or frame mounts causing damage to the frame. 

Trunnion eyelets are employed to reduce the overall shock length in a bike, enabling frames to have a lower standover height and more mounting options. They typically eliminate the need for mounting hardware, attaching directly to a bearing or using a frame-supplied spacer or washer. 

Not all bicycle manufacturers will state that their bike is 'Standard' or 'Trunnion', however. If you are able to locate their shock sizes, you will find they align with the specific lengths listed above and this will indicate which style of mounting is needed.

Bearing Mounts

Some manufacturers will also opt for bearing mounts instead of utilizing a DU bushing and mounting hardware. This will be specified by the bicycle manufacturer for the most part. The bearing mounts from RockShox fit in the same dimensions as 8x30mm hardware. They are larger than standard mounting hardware, so it is important that this is approved by your bicycle manufacturer.

Coil or air?

There is a lot of debate about Air or Coil and we are not here to convert you either way. When it all boils down to it, your bicycle manufacturer will recommend whether a coil or air shock, will work best with your bike. Some bikes support both and in those instances, it may be trying both to see what suits your riding style.

As the coil on coil shocks are a larger diameter that travels the entire length of the shock they will require more space within a far as to not contact tubes of the frame. There are some specifics when it comes to coil shocks in terms of fitment. For the sake of this article only talking about 2023 product onwards, please review the below:

Bike that need specific coil shocks:

• Commencal Meta TR Power
• Specialized Kenevo

 These two bike models are only compatible with a Super Deluxe Air shock OR a 2023 Super Deluxe Coil shock WITH a steel shaft. 

Shock Dimensions

Shock dimensions are crucial for a proper fit. Once you've determined your eye-to-eye, stroke, and mounting hardware requirements, you can delve into shock dimensions. These engineering drawings reveal potential clearance problems with your frame. Given our long history, we can't cover every shock we've made. Instead, we'll concentrate on RockShox products from 2023 onwards, as these are current and available in the market. This focus will assist you in ensuring compatibility and a smooth upgrade.

Measure Twice

When you have your shock it is important to cycle the suspension and make sure that there is no contact with the frame. We do this in the same way that we checked for space in the first few steps. It is important to let the air out of the shock and softly compress the suspension by hand. Below is a video on how to do so:

Hot tip: If there is low clearance, use a piece of paper between gaps to see if there's contact between the frame and the shock.

Known Fitment Issues

As a leading suspension brand, it's impossible for us to ensure compatibility with every existing frame and size combination. If you're considering a particular RockShox rear shock, we encourage you to consult your bicycle manufacturer. They may have insights into whether your frame can accommodate the specific shock you're interested in.

While we cannot cover all scenarios, we'd like to highlight that certain frames, particularly in specific sizes, might encounter challenges with certain shocks and potentially other sizes within that same model may not. It's crucial to exercise extra caution in such cases and seek clarification from your bicycle manufacturer for a precise assessment.

RC2T fitment issues: Super Deluxe, Super Deluxe Coil and Vivid Ultimate

• 2020+ Specialized Demo - The reservoir may contact and damage the frame when the suspension is compressed.
  
• 2020+ Cannondale Jekyll - Low Speed Compression dial will contact frame in the suspension cavity.  It is also difficult to inflate the shock. No option is optimal. 
  
• 2020+ Canyon Strive - Threshold switch contacts frame when compressed. Currently the Canyon will only fit with a Ultimate DH head fitted to a 230x65 Vivid (Part Number: 11.4118.088.009)
• 2020+ Orbea Wild - Low Speed Compression dial and Threshold Switch contacts frame 
  
• 2022+ Ibis Oso - Threshold Lever can contact frame 
  

Vivid Specifically

• 2020+ Specialized Kenevo - issues with air can size under bottom out
• 2022+ Transition Relay
• Trek Rail Gen 3 & Gen 4: Air can fitment issue
• 2021 - 2024 Forbidden Dreadnought: Air can fitment at 40% + travel
• Transition TR11: We have seen fitment issues on Medium and Large sizes 
• 2023+ Giant Trance X Advanced E+ Elite: air can contact with the seat tube
• 2018+ Lapierre Spicy - Vivid air can does not fit in the shock tunnel 
  
• Santa Cruz Hightower 2 and 3: Issues with fitment in shock tunnel
• Santa Cruz Heckler 8: Issues with fitment in shock tunnel
• Transition Patrol Carbon: Issues with fitment in shock tunnel

Advanced Compatibility: Shock Tunes

Shock tunes refer to the High Speed Compression and Rebound circuits within the shock. We won't dive into any 'custom tuning' but rather we'd like to highlight that there are internal changes made to the shock by the bicycle manufacturer.

Many aftermarket RockShox rear suspensions come with a standard shock tune that falls in the middle of the range for both Rebound and Compression. If you want to fine-tune your shock to your bike's specific needs, it's advisable to obtain shock tune information from your bicycle manufacturer, as mentioned at the beginning of this article. If you wish to make these adjustments, contact your local bike shop, as it's a job best done by a professional. 

The Piston Tuning Guide is an online resource online and instructs riders to customize their shock to their specific requirements from their bicycle manufacturer.

If you were not able to find the exact shock part number, refer to the steps above and have the shock tuned for your bike via a suspension professional. We have the Vivid Internal Shock Tunes available publicly. 

Looking to Learn More?

SRAM has fantastic learning resources, such as our service website and SRAM Tech YouTube channel.

• SRAM Service Website can be found here
• SRAM Tech YouTube can be found here
• SRAM Service FAQ