In our last instalment of the foo-foo bike project we were at a loss on how to proceed. We’d dive-bombed right on past the point of diminishing returns, ending up pressed against a glass ceiling that would have cost huge dollars and completely changed the character of the friendly XT225 to break through. The biggest problem was the rear shock.

Foo Fighter Project Stories:

Part 4

Part 3

Part 2

Part 1

During this project we’ve fought with the stock shock, re-valving, rebuilding, re-valving, rebuilding … a revolving door of ‘oh-so-close’ failures. The trouble is the XT’s shock, when coupled with the mods necessary to actually make it serviceable, such as heavier valving and stiffer springs, is just not beefy enough. We did get it working quite well, especially considering the short 7 inches or so of wheel travel, but really big impacts kept blowing seals. And each time the shock came apart to be repaired the problem got worse. Two very reputable suspension shops tried to fix it, and they did … until the first really solid impact anyway.

It’s not like there is a ton of room to do a shock-swap on the XT225 either. Between the weird length of the shock and the very limited amount of space available in the frame we were stumped. So we started searching for either for an older-style remote-reservoir 85cc motocross shock to modify or for simply a decent stock XT225 shock. Then Cogent Dynamics came to our rescue!

Cogent Dynamics made a name for themselves by building shocks for road race bikes and giant dual-sports. CD’s Rick Tannenbaum asked a bunch of questions about my weight, riding skill and suspension preferences before building one of his ‘Moab’ shocks for the Foo-Fighter. We didn’t go crazy with expensive stuff like remote reservoirs, hi- and low-speed compression adjusters or thrust bearings for the spring collars. No, we just wanted a good, reliable and modern shock that would bolt into an XT225 without fuss. We did ask for one mod, however; our shock was built a half-inch longer in overall length than stock to raise the ground clearance a little.

The rebound adjuster is in the normal location but has a much greater range of adjustment than a stock XT shock. We had Cogent Dynamics use our existing heavy 6.8 spring with the new shock, and we requested the valving be set at something appropriate for outdoor motocross. Not that we planned on motocrossing the little Yamaha, but we wanted to be able to hit stuff pretty hard. The finished Cogent Dynamics Moab shock is a work of art. Machined from aluminum, it looks very serious compared to the wimpy stock XT shock.

The CD shock was a tight fit, thanks to the large body, but everything went together without too much strain. The oversized preload adjuster on the Moab shock is sweet, making adjustments pain free. On the trail the shock performs well. It doesn’t blow through its travel or wallow like the stocker; it rides high in its stroke and refuses to bottom harshly. After a little fine-tuning with the rebound adjuster and we were pretty happy! Overall performance of this CD Moab shock isn’t quite as good as the last of our modified stock shocks was, but remember the valving on this new shock is guessed-at valving by Cogent Dynamics, and we had also been tinkering with the valving on our modified stock shock for over a year. The beauty of the CG Moab shock is that it can be serviced or re-valved just like any other quality motocross shock, so there is no question we can make it perfect. We love our new shock, and with a few minor valving changes we’ll love it even more. We just wish we’d called Cogent Dynamics first before spending so much time trying to make a silk purse out of the stock XT225 shock absorber.

Cogent Dynamics can make a shock for any application. You can visit them at http://motocd.com/cd/