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Sine Suspension System

Whether you are a top World Cup downhiller, EWS racer, or just a weekend warrior, one of the most important aspects to having your mountain bike perform at the highest level is understanding how to set up your suspension properly. With a basic understanding on how Sine Suspension functions and the set up recommendations below, you can easily have your Arktos working in tip-top shape in no time.

 

OVERVIEW

All Alchemy mountain bikes feature our proprietary Sine Suspension system, which was developed by renowned suspension designer David Earle. The Sine Suspension system is a one-of-a-kind dual short-link system. Sine was derived from superior design elements of David Earle’s previous coveted suspension systems. What makes Sine Suspension so unique and superior is that it didn’t start with engineering, but rather with a focus on suspension kinematics. By shifting focus from engineering to the bike’s movement and design it, allowed David to create the ideal mountain bike suspension system that performs exceptionally on all types of terrain, while also optimizing the bike design itself.

 

KINEMATICS

So, let’s start with how Sine works. As the bike moves through the travel, the rear wheel path resembles a mathematical Sine curve. At the beginning of stroke, you see suspension regression in order to allow the bike to absorb small bumps and provide climbing traction. As you move into the middle of stroke the suspension moves into a progressive shock rate. This prevents wallowing on big hits or in hard and fast corners.

 

When you really push it and open the end of the stroke, the suspension becomes regressive again to enable full use of the rear wheel travel. This pattern is specifically designed to minimize chainstay growth, improve pedalling efficiency and keep the suspension active under braking. All these factors make for an incredibly lively and efficient ride.

 

HOW TO PERFECT YOUR OWN SINE SUSPENSION

The Sine Suspension system is optimized for use at 30% overall sag. However, personal preference and riding conditions can influence the amount of sag desired. We encourage you to mix it up and experiment to find what works best for you. The “sag” is the amount of travel the shock uses under normal rider weight. An ideal suspension sag will optimize the three areas of travel: negative, mid-range, and deep travel. You’ll know you’ve perfected the sag when you experience a plush, small bump feeling in your negative travel, a firm and lively feeling in your mid-range travel, and a ramping and bottomless feeling in you end travel.

HOW TO CHECK SAG

  1. Gear up head to toe so you start with an accurate rider weight.
  2. With someone holding the bike, stand on the pedals and get in your normal riding position on the bike.
  3. Bounce up and down on the bike, compressing the rear end of the bike and the rear shock; when you are steady again, have someone push the travel ring up the shock against the wiper seal.
  4. Dismount the bike gently (as not to move the travel ring).
  5. Check your shock. The amount of stanchion shown between the wiper and travel ring is your sag. (30% sag would show 21mm of exposed stanchion between the wiper and travel ring.)
  6. If there is less than 30% sag, remove the valve cap and let out some air with a shock pump. If there is more than 30% sag, add more air. A good starting point is to pump your rear shock PSI to your rider weight and work from there: 180 lbs=180 PSI.
  7. Once you are dialed put the cap back on and you are ready to go ride some trails.
  8. Use the Tuning Guides to really dial in your suspension.

Still not sure if you’ve got your Sine Suspension up properly? – Contact us at alchemy@alchemybikes.com or visit our Denver factory and we can help you find your perfect settings.

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