horriefic said:

I have been really trying to understand the definition of a progressive shock suspension (rear suspension) for some time, but I still don't think I understand it fully.

What does a progressive suspension mean, compared to a linear suspension? Does it mean it's soft at the start, but gets harder at the end?

What does it mean that a suspension 'ramps up' at the end? Ramps up meaning it is harder (or softer) at the end of its travel?

Also, some rear suspension designs (ie. the suspension linkage design and not the rear shock) are defined as progressive. What does this mean? For such suspension designs, better to use a linear shock, or also a progressive shock?

Also, some rear suspension designs have a falling leverage at the start, but rising after the midstroke towards the end. And some are rising at the start, but falling after the midstroke towards the end. What does this mean?

And finally, what does it mean by a rear shock's 'leverage curve'? And in some of the leverage curve pictures, the Y-axis is names mm/mm. What does this mean and how to read this graph?

Thanks in advance for the clarifications.

Its a tough thing to explain but I will give it a shot.

A linear shock means that the amount of force needed to compress the shock is consistent line. Meaning if you were to look at a graph that showed how much a shock moves compared how much force is applied, the graph would show a straight line. This would be the red line on the little graph I made on paint in 5 seconds.

On the other hand, A progressive shock means that the amount of force needed grows as the shock is compressed. The line would be curved, because the amount of force needed to compress the shock progressively grows as the shock compresses. This would be the blue line.

Its a crude graph, But hopefully it gets the point across.

Now a suspension ratio is how much the rear wheel travels compared to how much the shock moves. To get a leverage ratio, you take the rear wheel travel of a bike and divide it by the shock travel. So say you have a bike with 150mm of rear wheel travel and your rear shock has a 57mm stroke. You take 150mm and divide it by 57... giving you a leverage ratio of 2.63 : 1. So for every 1mm your shock moves, your rear wheel moves 2.63mm of its travel.

Get it? Now, that describes a straight rate leverage ratio. A raising/falling rate ratio would mean that the ratio changes as the shock is compressed. Rising means the shock would ramp up at the end of its travel and a falling rate means it would drop off at the end. A rising rate shock would start off at say 3.0 : 1 and end at 2.5: 1 and falling would be the opposite. The numbers make it confusing since the rising rate ratio shrinks and falling rate ratio grows, but remember that the number means how much the wheel moves compared to the shock. The smaller numbers means shock has to move more to get the wheel to move. This means that the smaller number being at the end causes the shock to move more for a given amount of wheel travel causing it to ramp up, or rise at the end. Falling is the exact opposite.

Rising rates are also considered progressive. and leverage ratios can change in many different ways, depending on the suspension design. Hopefully this helped and didnt confuse you.