DragBikeMike wrote on 10/08/21 at 17:40:29:
Gary, exceedingly good posts on the suspension. My compliments. I have some questions for you.
You set the free sag on the forks at 10mm, which is 8% of the 127mm travel. Is it OK to also set the free sag on the rear shocks to 8% of the travel? For instance, the stock rear wheel travel is exactly 2.69”. That would work out to free sag = .215” (5.5mm), very close to your estimate. Once I replace the rear shocks the wheel travel should increase so I want to know if 8% is a good target.
I’m baffled on the free sag guidance, if less than recommended you need heavier spring, if more than recommended you need a lighter spring. That seems counterintuitive. I saw similar guidance on an Aussie website. I’m missing something. Can you elaborate?
Please tell me if I have the procedure correct. Step 1, determine baseline. Step 2, establish and set correct race sag for given travel. Step 3, check free sag to verify proper spring rate.
Dave,
You were heading in the wrong direction...but then you saved yourself. You don't set static sag - you set race sag. Static sag is the result of the race sag and it tells us about the spring rate. If after setting the race sag you have too much static sag, that is a sign that the spring rate is too high. Why is this? Simple, you didn't need much (or any) preload to achieve your race sag figure. Conversely, if you have too little static sag, it means that you had to crank in a whole lot of preload to get the right height, and now the shock is jacked up - and there isn't enough spring travel left.
Dave, if you are going to take the time and spend the money here - do it right and do it once. It will be worth the effort. A good shock is one that is rebuildable. This way if a seal fails, you don't throw away the assembly, you replace the part. Also, if the shock is rebuildable, that means you can rebuild it to a specification that you choose. For example, if you don't like the rebound compression, you can change the shim stack (flexible washers). Being rebuildable means that you can choose the oil viscosity, the amount of oil, and the amount and pressure of N2. These are all thing that effect the operation of the shock - and your comfort.
A good shock will have a preload collar, not 5 clicks. What happens if you are between clicks?
My bike is comfortable. Period - no disclaimers on that. Well one...I have more travel which gives me more options to achieve comfort. But there are plenty of comfortable Harleys out there and they too have limited travel. It's not about how much travel you have, but what happens between the end points. The spring has to adequately support the bike and rider in the right location/zone, and the damping has to control the speed of the motion. If you are chasing spring rate for comfort, you are doing it wrong. If the sag figures are correct - then its not the spring - its the damping. That's why in a quality shock you have control of the damping.
If you put Intruder shocks on your bike, you are replacing crap with different crap.