Coil or Air?

Some people swear by air shocks - others by coil.  Sure, there are obvious benefits to air shocks, such as generally being lightweight, and less expensive than a coil with titanium spring.  However, the way these shocks work with different suspension linkages also influence people's decisions.  Since air shocks increase dampening exponentially as a shock compresses, frame designers often use a regressive leverage rate towards bottom-out to create the desired "linear" feel.  This is why some frames like the Ibis HD, which uses the DW Link, instruct riders to only use air shocks with their frames.  If a coil shock was used on this bike the suspension would end up feeling softer as you compress the linkage past the sag point towards full compression - essentially providing little bottom-out resistance.

On the other hand, many 4 bar frames have linear linkage feels, this gives the option to either run a coil shock or an air shock.  A coil shock - which is inherently linear coupled with a linear linkage - will give a feeling of controlled and predictable travel.  This is largely because the suspension would compress with an equivalent amount of force throughout its travel.  Conversely, if you ran a progressive air shock on this type of linkage, you would get a progressive feeling suspension.  So you have the option to run either coil or air with a linkage like the CHUMBA VF2 or XCL.

It's conceivable that some riders have used coil shocks on frames not designed to accept the linear rates of these dampers.  It's important to always double check with manufacturers first before swapping out different shocks to make sure that the results of the damper change will coincide with the desired ride feel.

You can shoot any suspension set up or tuning questions to tech@chumbaracing.com. Just to be clear though, all of CHUMBA frames were designed to accept either coil or air shocks, and we encourage the use of coil shocks.

Happy trails.