I found this quote from Cane Creek regarding an IS41 headset:
“Unfortunately we don’t have an IS version of the Viscoset. As for the second part of the question, I asked Jim Morrison, our Principal Design Engineer and all-around headset guru and here is what he gave me:
‘Repacking a normal headset bearing with heavy grease will add damping, but really not that much. It’s a low-risk proposition, though, so it would be worth trying. I’d try to source some Nye Lubricants Fluorocarbon Gel 868H or VH (heavy or very heavy), carefully pop the seals, clean out as much grease as possible with a solvent, then pack as much damping grease in there as possible. The bearing will feel damp-y in your hand, whether that’s what you’re looking for at the handlebar is a personal preference kind of thing.’
Technical FAQ: Drivetrain friction test, steerer-damping headsets – VeloNews.com
I think I will try the damping grease.
So I had to wait for the spare bearings to come from Alibabba, then for the polar vortex snow to melt, and for my enthusiasm to thaw as well. But I finally got to try riding my V20 with damping grease in the headset bearings. I decided to go with Nye 767, which is rated down to 0C (32F). It is thicker than the 868VH, which is rated to -20C. But my working temperature rarely goes below 0C, so I think I'm good.
First I had to degrease the new bearings. I flushed them with WD40, then soaked in alcohol. Then I had to re-pack them with the thick grease. It's hard just to squeeze it out of the tube. Then the bearing is hard to turn once you get some in. But the good news is that it's so sticky that as long as you keep a bead in the gap, it just gets pulled in when you turn the bearing. So it's not that hard as long as you have some patience. But wear nitrile gloves.
With the factory grease, the bearings turn easily by hand, but do not spin. When degreased, they spin freely. With the Nye grease, they turn only very slowly with considerable effort.
Made up in the headset, the resistance is very dependent on the axial preload from the headset cap screw. I found that when I cranked down the headset as tightly as I dared, much tighter than I would usually tighten it with a regular greased bearing due to binding, there was a lot of resistance, but no binding. I backed it off slightly, so that there was still enough resistance that the steering would stop and hold position after a few damped oscillations if you swung it unloaded. The bearing still moves freely, but slowly with effort, so it's not binding or sticking. I think this is because the grease is so thick and sticky that it stays in-between the balls and race so there is no metal-to-metal contact.
I have not ridden in a while, so my memory may be faulty. But my first impression is that the ride was more like a Cadillac. The steering resistance was noticeable if you noticed, but not objectionable. The bike goes where you point it; but if you start a turn, it wants to keep turning. I assume this is because the trail force cannot overcome the resistance. This is not a problem, just a noticeable difference. It also seems a lot less twitchy, so the mental workload was less. I could almost ride hands off, and could easily ride on the tops, which I didn't dare do before. Again, these are just first impressions after a single uncontrolled experiment by a recent convert. So YMMV.
I think the next thing I will try is to take a couple of spare bearings apart, throw away the ball spacers, and kitbash them into a bearing with a full compliment of balls, and put this on the crown race bearing to increase its load bearing capacity. I don't think it's necessary to do this for the top bearing since the lower one is more heavily loaded because the weight adds to the preload (that's why some MTB have larger bottom bearings).
I'm not sure if I'm overloading the bearings, so I threw the stock bearings in my ditty bag just in case they get crunchy.
