Is your suspension too stiff, or does it just feel harsh? It is easy to jump to the conclusion that the discomfort you are experiencing is because your suspension is overdamped or your bike is over-sprung. However, more times than not, your suspension feels stiff because it is too soft and it’s riding deep in the stroke.
We have all heard someone say, "My suspension is so stiff that when I hit that bump it doesn’t even move." Well, though this could be true, it is not always a result of the suspension being too stiff. When your suspension is compressed, it is meant to become stiffer. You have the main spring force increasing, the internal air pressure rising, the pressure spring increasing cartridge pressure, and a linkage giving up a mechanical advantage at the rear wheel. All these things should show you that more displacement in the fork or shock produces a greater force.
The next time you have your fork off your bike, compress it at the top of the stroke a couple of millimeters and see how much resistance you have compared to when you compress the fork down 100mm. Much softer up top, right? The same goes for on-track dynamics; the higher in the stroke we can keep the bike on average, the softer it is going to feel.
We just had a test with the AEO Powersports KTM Supercross team, and we saw this firsthand with their new rider, Talon Hawkins. He called for the test because he was searching for more comfort in the front and rear of his Supercross bike. After watching his warm-up session, it was easy to see that his bike was riding too deep in its stroke, where the harshest part of the travel resides.
We went stiffer on the valving and had him try it. He came back commenting that comfort was up. We then tried stiffer springs with less preload; again, comfort increased. There are many ways to make your bike ride higher in the stroke, so it is important to choose the method with the fewest negative ramifications. Your feelings are telling you the truth: the suspension feels stiff. But, what you need to question is why it is feeling stiff. These feelings can be misleading and are not solely affected by stiffness.
Balance and positioning can be misconstrued as well. An example of this goes back to a test I had with Ryan Dungey that focused on shock setup. We had just gone to a stiffer shock, and he commented on the increased comfort and lower ride height. Well, after a more thorough analysis, we realized that it was not necessarily lower but instead getting more movement when he accelerated. This "drop" in the rear was happening, because the rear was starting at a higher position due to stiffer compression instead of its starting point being lower in the stroke.
You can also see proof of suspension changes causing riders to load the bike differently via data acquisition. Say you have a good bike balance and you throw in softer fork springs for a test. Suddenly, the data shows that the rear is riding too deep in the stroke. How can softer fork springs load the rear more? This can happen because the rider is unconsciously picking up on the unbalance and is now riding over the rear. The moral of the story is: Listen to your feelings, but be open to the idea that the changes needed might be completely opposite of what you would naturally think.
was an in-house WP suspension technician at Red Bull KTM for 10 years. He has won championships in Supercross, motocross and off-road racing. Now, Mark’s company, Research Engineering Performance or "REP," is partnered with AEO Powersports. They offer factory-level experience to everyday riders.