After receiving the Opium, I toyed around with it for a while scratching my head. I truly didn't want to try another headset with an O-ring that holds the steerer centered like King does, but this one's different...the upper cap COMPRESSES the o-ring so it doesn't have as much of an issue with slight steerer size differences. The whole unit is rather brilliant, tiny and LIGHT. By using the actual cup as the outer race of the bearing, Crank Brothers were able to eliminate redundant parts, and thus make it a LOT lighter. It even has a 36 ball complement bearing for load handling.
It comes with a special installation tool for pressing in the upper bearing, both cups, a top cap, upper cap, crown race, and 2 o-rings. One o-ring is for steerer capture, and one for a seal on the lower bearing. I found this a little cheesy for sealing, but decided to give it a shot and see what happens. I knew that if it was ever going to let anything in, I'd be able to get it to do it in the wonderfully muddy spring trails here in Colorado.Installation
As with all headsets, it's a measure and press the cups in operation. Since these run the cup as the race for the bearing though, it is suggested to press the cups in one at a time, so the races don't become ovalized at all from cocking sideways in the headtube bore and flex the race area. I followed those suggestions and used the supplied tool to press in the upper cup with a Park headset press, and followed that with the bottom cup. Easy as pie, it pressed in more easily than any other headset I've done, straight the whole way, never wanting to go off sideways.
Pressing with special tool
After the cups, I removed my old Cane Creek crown race and installed the Crank Brothers one. This was a VERY tight fit, I suggest using the right tool, as you'll crack a PVC pipe trying to bang this one on. Once that was on, you slide the lower seal on the steerer, and run the steerer up thru the cups, slide on the other o-ring, and top plate and stem. When you tighten the headset down, it squeezes the o-rings into their seats, and all of a sudden all play disappears!
Check that stack height too! I was running no spacers with my Cane Creek! Ride testing
Play free and ready to ride!
I have so far about 5 trail rides on it. If you know me in the forums, you know that our trails are nothing to scoff at and as such test parts to their limits and past them sometimes. Trail bikes for us are no less than 6 inches of travel, and slack geo. We aren't your typical trail riders here. It's been wet here so I have been hosing down the bike after rides too, further testing the sealing of it.
The headset has been operating flawlessly. No creaks, groans, pops, whines, grinds, squeaks, or other ridiculous noises I've had happen in the past. It keeps dirt out well, but do note if you drive thru salted roads in wet weather a tiny bit of salt may get under the lower seal. It doesn't get in the bearing as that has its own seal, but it gets to the race. If this happens, just give it a good rinse and scotchbrite rubdown to get rid of the rust on the race.
Mud rides and hosing and not a trace inside the top bearing
Lower looks grit free too, just a little sign of moisture
No dirt has gotten in, and we have nasty gritty dirt here that wreaks havoc on bearings so that's a big thing to me. The system works, and works WELL. I might have just found the best headset for me!http://www.crankbrothers.com