Introducing: Your rear suspension

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To help you better understand what happens when your rear wheel moves up and down, we present two illustrations. The animation on the left shows how everything back there fits and works together. The one on the right is for those who grew up before MTV.

Susp-ani.gif Suspension illustration.jpg

Parts

This view is from the left side of the bike, so the front is at the left side of the picture and the rear at the right.

  • The thing that looks like a shock absorber is, ummm... a shock absorber. Its main job is to keep your rear tire on the road (the fork springs do the same thing up front). When a bump forces the tire up, the shock sends it back down. This is a delicate balancing act. If the wheel moves too much, or too little, it won't have proper contact with the ground and traction will suffer. Both are bad, but thankfully there's a fairly wide margin of "good enough", although it does get more narrow the faster you ride. More information
  • The black piece with everything connected to it is the frame. This is what nearly everything on your motorcycle is connected to. It supports the forks, the engine, the seat, and, of course, the rear suspension.
  • The long, rectangular thing attached to the frame is the swingarm. The Ninja 250 has a double-sided swingarm, so there is one piece on each side of the rear wheel. The wheel attaches to the swingarm via the slot at the rear. The swingarm pivot is where the swingarm attaches to the frame.
  • The diagonal bits running from the shock linkage to the swingarm, making an indirect connection between the shock and the wheel, are the tie-rods, or 'dogbones'. There is one on each side.
  • The elbow-shaped piece at the bottom is the Uni Trak shock linkage ('rocker arm'). This is the part that connects the frame, tie rods (dogbones) and rear shock together. The rocker arm is there so the rear shock will have more travel before transferring any bumps to the frame (which is bad). This provides for better handling and comfort.

Explanation of suspension damping

This deals mostly with how the rear suspension acts to keep your wheel on the ground, but the front works the same way.

Damping is the shock's ability to prevent the forces of the road imperfections from being repeatedly transmitted to you through the bike's chassis. Holding the bike's chassis from the tires are springs. Their job is to keep the bike suspended in the air, at a set distance from the surrounding parts.

When the tire hits a road imperfection it moves up and down. The spring compresses and stretches in order to prevent the chassis from moving up and down in relation to the imperfection. A spring, on its own, will keep expanding and compressing over and over again. So, to stop the movement of the spring, you have a shock absorber.

Now, if you have a shock with a high amount of damping, then very little of the spring's movement gets transmitted to the chassis. This makes for a nice smooth ride, but it feels like you are riding on a marshmallow. If you have very little damping, then most of the forces do get transmitted to the chassis, and it feels like you are riding on rocks. So, the adjustments that are on adjustable shocks are there to allow you to bring the suspension to a happy medium between riding on a marshmallow and riding on a rock.

Set your (adjustable, non-stock) shock to what feels best to you under all conditions, and you will be happiest with the bike.