September 15th, 2009 by 
Gregg
To our valued Customers, Riders, and members of the CHUMBA family:
There have been many exciting developments with CHUMBA over the last few months. But, before I get into that, I would first like to thank all of our loyal supporters and riders, and let everyone know that CHUMBA is truly on its way to becoming one of the world’s most prestigious bicycle brands in the world. CHUMBA is focused on quickly developing and tuning our suspension technology, along with offering aesthetic and performance options unmatched by any other high-end company. Here are a few of
the things we’ve been doing:
1. Identifying Suspension Curves and Accompanying Shock Settings to
Maximize Performance
To make things easy – just remember that a decreasing leverage ratio means compression resistance is increasing; and increasing leverage ratio means compression resistance is decreasing. Just remember the analogy of a lever – imagine that you are trying to compress the shock with a lever. The longer the lever is the easier it will be to compress the shock; so the more you increase your leverage ratio, the easier it becomes to compress a shock. As your leverage ratio decreases, it will become harder to compress the shock.
As you can see in the chart above published by Trek’s R&D team, the leverage ratios at a given area in shock travel vary tremendously for some manufacturers. As you can see on the DW-Link Mojo – the dramatically varying and increasing leverage ratio towards the end of stroke means less bottom out resistance from the linkage. Additionally, the Santa Cruz Blur probably has one of the largest varying suspension rates, going from as high as 2.7 all the way down to 1.65. Further, on the DW Link and VPP, the leverage rates increase and decrease all throughout the curve – making for varying feels throughout the travel.
As you can see with the VF2 – the leverage ratio is predictably constant – making the travel feel extremely consistent and predictable when compared with the competition. You can see the variance of the compression resistance is minimal, being slightly regressive with a small amount of bottom out progressiveness at the end. Yamaha MX and CHUMBA test rider Dustin Nelson put it well when he says “linear rates give you the most amount of controlled feel over travel” – as you don’t need to compensate suspension feel with a varying leverage rate to try and make up for pedaling input from
the suspension. - Stay Tuned for Part II
source: Alan Kang. CHUMBA
September 17th, 2009 at 9:12 pm
It’s interesting to see that even w/ different curves, where the stumpy, blur and mojo intersect is around where \sag\ would be: they have about a 2.7 ratio as their average feel, while the Trek and Chumba have the lower ratio of around 2.5 at sag. I take this to mean that it is easier to activate the suspension of the Chumba and Trek from the sagged position. Would I be correct to assume, rebound dampening factors being equal, that the Chumba would return to the sagged position easier (faster) because of it lower ratio in the initial travel versus the Trek’s higher ratio in it’s initial travel?