26.8.10

Bike Suspension Info

Suspension Overview – Pros and Cons

Are you still confused about shock technology? Here is a list of the pros and cons for each type of technology. If this does not clear the air. Post your comments and questions.

Single Pivot
Advantages Disadvantages
  • Simple Design
  • Can be very durable
  • High clearance
  • Good for large impacts
  • Linear rear wheel travel
  • Little reactivity to small hits
  • Not a progressive ratio
  • Subject to Pedal feedback
  • Subject to brake jack
Swing-Link (Faux-Bar)
Advantages Disadvantages
  • Reactive to small hits
  • Variable wheel/shock ratio
  • Improved shock position
  • Single Pivot Wheel path
  • Complicated linkage for small benefit
  • Decreased clearance
  • Subject to pedal feedback
  • Subject to brake jack
  • Linkage near rear wheel
FSR – Horst Link
Advantages Disadvantages
  • Reactive to small hits
  • Variable wheel/shock ratio
  • Handles large hits
  • Progressive leverage ratio
  • Non-linear/vertical wheel path
  • Long linkage arms
  • Decreased clearance
  • Linkage near rear wheel
VPP
Advantages Disadvantages
  • Variable wheel/shock ratio
  • Reactive to small bumps
  • Non-linear/vertical wheel path
  • Regressive leverage ratio
  • Decreased clearance
  • Subject to pedal feedback
  • Chain Growth
DW – Link
Advantages Disadvantages
  • Variable wheel/shock ratio
  • Progressive leverage ratio
  • Non-linear/vertical wheel path
  • Decreased Clearance
  • Difficult shock placement
  • Chain Growth

Bicycle Suspension VPP vs DW-Link

The Virtual Pivot Point (VPP) and DW-Link are two relatively new suspension designs on the market. They both offer great benefits in ride quality over other, simpler designs but also have a few downfalls that will be discussed.

The two designs look very similar to one another, but are in fact quite different. Both designs use two links which connect the front and rear triangles of the bike. This allows the rear wheel to move independently of the frame in a close to vertical, sometimes rearward wheel path. The differences come in the way the links are positioned. Looking closely at the linkage, as the bike moves through its travel you will notice that the two links rotate in the same direction on a DW-Link while they are opposing on a VPP design. What this results in is a progressive vs. regressive leverage ratio. In English, a progressive ratio means that the further into the travel you are the harder it will be to further compress the shock (lower leverage ratio). On the contrary, a regressive ratio will get easier to compress as you move through the travel (higher leverage ratio).

Have a look at the two designs, they look similar, but are distinctly different.

VPP

VPP - Regressive Ratio

DW-Link - Progressive Ratio

DW-Link - Progressive Ratio

Bicycle Suspension FSR vs Rocker Link

The Horst-Link and the Rocker Link are two seemingly similar suspension designs with very different ride characteristics. First off it should be established that the Horst-Link was designed by Horst Leitner in 1991 then purchased by Specialized in 1998 and renamed FSR. If you purchase a bike that uses this linkage in the USA, your bike will have a specialized sticker on it for this reason. It should also be noted that not all bikes using FSR are identical. The position of the pivot, and design of the linkarms will alter the ride characteristics too. It is this reason that a DH and XC bike can use the same system.

A bike that uses FSR will have the rear-most pivot positioned below the axle of the rear wheel. What this does is creates a much more vertical path of wheel travel that a single pivot. Vertical travel is preferable to a single-pivot arc as it better corresponds with the forces applied while riding. FSR linkage also limits chain growth, pedal feedback and brake jack.

Four Bar FSR Linkage

The Rocker-Link is sometimes referred to as ‘Faux-Bar’ or ‘Walking Beam’ suspension and looks very similar to FSR except for the rear pivot location. On a Rocker-Link design the rear pivot is placed above the rear wheel axle. The wheel subsequently is attached directly to the front , main pivot and follows a path identical to that of single pivot. This design is subject to the pedal feedback and brake jack associated with single pivot.

Faux-Bar Linkage

Both of these suspension systems are widely used and have some distinct advantages and disadvantages. The Rocker-Link is subject to a less than optimal wheel path while the FSR is limited due to its patent restrictions in the USA.

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