Tailor Your MTB Suspension
Christian's custom Cannondale Habit
About the author
Known for his creative lines and solid bike control, Christian is a professional athlete for Cannondale Bicycles, Vittoria Tires, ZOIC Clothing, ENVE Composites, and Chris King Precision Components. He has only been riding full suspension MTBs since 2018 but immediately fell in love with mountain biking and quickly gathered a social media following due to his style on a trail bike. He is also a heavily booked MTB coach, training riders on topics from cornering to jumping.
Suspension can make or break even the best bike. These days it is adjustable to an mind-boggling degree. It is, however, another aspect of bike setup that is very preferential. Let me break it down for you:
Air vs coil suspension
Air has a quicker ramp up, meaning it works better for big hits and having good mid stroke support (harder to bottom out). Air shocks tend to be lighter weight (oxygen is much lighter than steel), making them ideal for XC, trail, and jumpers.
Coil shocks tend to be heavier but better for supple, forgiving absorption of repetitive bumps in the trail. You hear coils described like riding on a big shag carpet, meaning they’re great for downhill or enduro riders who want to float over fast, chunky sections.
An age old debate: Air or Coil?
To control ride feel on an air shock you can add or let out pressure. This will shift the entire range of sensitivity, meaning more pressure will make the suspension more difficult to compress at every stage of the travel. Same goes with a higher pound capacity coil—stiffer spring is harder to compress throughout the full travel.
If you are taking big hits that are likely to bottom out the bike, or want your bike to feel stiff and responsive (at the expense of comfort), pick a higher pressure or stiffer spring. If you want a more forgiving ride that absorbs bumps more readily, but can be more easily bottomed out, choose a lower pressure or less stiff spring.
You can add or remove air from your fork by removing this knob to access the schrader port
Tokens, or volume spacers, are an amazing way to tinker with the behavior of an air suspension system. They are plastic pieces that reside inside the air chamber to take up air space. Since there is now less air to compress, the suspension becomes more supportive in the middle and end of stroke. This means you can run a lower pressure, to gently absorb small bumps (beginning of stroke), but still have the support you need to avoid bottoming out off a big drop (end of stroke).
Many riders who do lots of jumps/drops run numerous volume spacers so that their suspension is supportive for big hits, but without compromising the small bump compliance that makes general trail riding more comfortable.
Coil suspension it is not as tunable, but there exist varying durometers of bottom out bumpers, which help smooth out the action of bottoming out a coil shock.
We already talked about the part of the suspension that is controlled by air or metal springs, but there is normally a second circuit within the suspension that is controlled hydraulically. This entails the movement of oil/fluid through special valves that can be adjusted to change the characteristics of the suspension feel.
One of these adjustable circuits is rebound, which controls how quickly the suspension will re-extend to its unloaded state after being compressed. Fast (open) rebound means the suspension will spring back quickly and slow (closed) rebound means it will spring back more slowly. Too fast a rebound can have the propensity to catapult riders over their handlebars while too slow a rebound can leave the bike feeling sluggish when jumping. I find it best to leave it near the middle and only tweak a little bit at a time until you find your preferred settings.
See the red knobs hanging from the fork? The upper controls high speed rebound and the lower controls low speed rebound
The second hydraulic circuit control is called compression—this is the opposite of rebound, in that it controls how quickly the fork can be compressed. On high end forks/shocks there is normally low speed compression (behavior for big, slow hits like jumping or dropping) and high speed compression (like hitting a quick rock while zipping through a rock garden).
The outer knob is labeled for high speed compression adjustability and the center knob is labeled LSC (low speed compression)
As a jumper I like adding a little bit of low speed compression to my suspension for additional hydraulic support. Racers, on the other hand, would probably prefer less high speed compression to more readily absorb rock bumps.
The last element of your suspension system that tends to be commonly overlooked is your tires. They come in many different volumes, thicknesses, and treads. They can also be pumped up to a whole range of pressures to change ride feel. Lastly there are various types of tire inserts, which are effectively volume spacers for your tires.
Downhill riders needing cushion and support would likely pick:
A mid-volume tire (2.4 - 2.5” width) with a very knobby tread (like a Vittoria Mazza), pressurized to 28-35psi (less likely to burp pressure on a big impact), with a tire insert like the Vittoria AirLiner (adds additional bottom out support, as it functions as a volume spacer and is composed of foam which can compress and prevent the metal rim from pinch-flatting the tire when coming in contact with a rock).
An XC rider, on the other hand, would want:
A lighter weight, narrower tire (2.1 - 2.35” width) with a semi-slick tread (like a Vittoria Barzo or Mezcal), pressurized to 18-24psi (since they won’t be hitting any massive impacts), with no insert to save weight (unless they have the propensity for flatting on rides due to sharp rocks or occasional impacts).
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Nice post. I learned something!