In our Aug/Sept issue we met with Tom Smith from Coppersmith suspension services to test the Ohlins TTX rear shock and loved it. In our last issue we rode a Yamaha YZ250F with Ohlins suspension front and rear and the suspension couldn’t have been sweater. The time had come for us to get some of these suspenders on one of the EDM test bikes long term. We spoke to Tom at Coppersmith and he agreed to lend us a set. Oh joy! Before assembling the rear shock Tom wanted to have the shaft covered with a DLC finish and we wanted the fork legs to have the same finish. The parts were sent to our friends at Extremeion for Diamond Like Coating. With that we had our suspension parts to install on the 07 RMZ450. Since most of the riding that gets done on the Suzuki is MX we asked Tom to valve accordingly. He makes some small changes to the shim stack from the way they come stock.
Since Segal is the one who rides the RMZ most, springs were set to accommodate his riding weight of 195 lbs. Stock fork springs are 47 kg. Tom suggested 42kg to let the fork ride further into the stroke for a more compliant feel. The stock rear rate is 5.5 kg and we went with a 5.2 for a good balance with the front. The oil range is between 310 and 395 ml. We started at 340 to be in the middle.
We have been raving about the Ohlins suspension ever since we first tried it. You might be wondering what is so special about this stuff? Let us start with the fork. The TTX cartridge kit completely replaces all the internals of your OEM fork utilizing a cartridge that is nitrogen gas charged designed to maintain equal pressure on either side of the valve/shim stack.
By doing this, Ohlins is able to deliver the highest level of performance and handling you can achieve before going to a works suspension. As your stock fork is working you have different levels of oil pressure on each side of the valve and shim stack. As oil is being forced through the small openings you have greater pressure on the side the oil is coming from and less pressure on the side it is going to. This negative pressure creates something called cavitation, which causes inconsistent damping and leads to higher oil temperatures. Higher oil temps lead to premature oil fatigue which leads to wear on your moving parts. Whew!
The Ohlins system, being pressurized, eliminates this cavitation by balancing pressure through the use of nitrogen gas in the cartridge. The gas and oil are separated by a small piston. It’s pretty cool. The obvious benefit of this is a more consistent, responsive fork. The not so obvious benefit is the fork runs cooler making thermal breakdown of oil less likely.
Installing the Ohlins cartridge is really simple. You drain the oil from your fork, remove the OEM cartridge, replace it with the new one from Ohlins, add fork oil, reinstall the fork on your bike and you are ready to go. The entire process takes about 2 hrs the first time through. It’s no more difficult than removing the OEM unit.
The TTX rear shock utilizes the same pressurized nitrogen technology as the fork kit. However it completely replaces the OEM unit. Tom suggests running the sag somewhere between 105 and 108 mm. Letting the back ride a little low makes it more stable at speed. We ran the RMZ at 108 for loamy track and 105 for tracks with harder dirt.
In addition to compression and rebound damping the Ohlins rear shock has an adjustment called the CSC adjuster. CSC is an acronym for Chassis Stability Control. What it does is this, it allows you to make global adjustments to compression and rebound. Say you are going trail riding with you buddies after work one day and your suspension is set up to ride at the MX track, super stiff to deal with landing from jumps. Rather than mess around with compression and rebound screws, you open up the CSC circuit 2 or 3 clicks and it’s super plush but retains the comp/rebound balance you already have. Pretty cool. We tried it on several occasions and it really works well. Just remember to change it back when you are at the track, it makes a big difference and your bike will feel pretty bad on a track with trail settings.
With the RMZ we started with the settings as they came from Coppersmith and found the front going through the stroke a bit fast for our liking so we dialed in the compression two clicks at a time until we found a setting we were happy with. We did the same for the rear. and finally settled on a base setting of 7 comp 11 rebound on the fork For the shock we settled into 8 on comp and 12 rebound, the CSC was left at 18. For trails we had to really open things up. The fork went to 18 comp 20 rebound and out back we opened the CSC to 22. What a smooth ride!
In the end we really dig the Ohlins kit and think you will too. It’s not cheap at $2,376.00 but you can’t get any closer to a works suspension than this. A works suspension should run around $6,800, the Ohlins price is sounding better already!