Wednesday, October 2, 2013

Suspension Design - Santa Cruz Heckler Vs. Ghost Cagua, Part 2

Okay.  I promised a second post where I focused on wheel path an other suspension attributes.  I think these diagrams are very telling.  We'll start with the Heckler, because it's pretty straight forward.
As you can see, pretty simple.  Sorry for the shitty diagram.  This is just a screen shot from Autocad, where I build my simple little suspension models that I use to build the graphs that were shown in Part 1.

Anyhow, what we can learn from this diagram...not much, really.  Other than that the rear axle follows a simple path laid out by the main pivot.  Let's move on to the Ghost Cagua.
This is a little bit more complicated as it includes instant center.  The instant center (IC) is the point that the rear wheel rotates around.  For the Heckler, that point is simply the main pivot.  On the Ghost, where the rear wheel path is dictated by the shock linkage and the swingarm, this is not so simple.  You can see, the IC starts out way in front of the bike, and gradually moves down towards the bottom bracket, near the end of travel.  What does this mean?  Nothing, really.  Weagle will probably talk to you for hours about IC, but in my mind, it's an end, not a means.  What's really important is what happens with your chain growth.  Yes, IC will have an impact on your braking characteristics...but there's so many other important factors in braking that override the effect you IC would have, why bother?  I anticipate contradiction.

So let's look at the wheel path of these two bikes.  Remember that they are vastly different suspension designs.  Let's look at them side by side.
   Look pretty similar, no?  Let's overlay them.
That's what I thought.  I'm not even sure which is which.  Does it really matter though?  Two vastly different suspension designs, pretty much identical wheel paths.