[CyclingJunkie]

I was in the process of swapping out my chainrings and decided to take my bottom bracket out and give it a good cleaning/regreasing while I was in there. After taking both bearing cups off of the bottom bracket shell I noticed the grease inside was a rusty brown color. I also noticed that the cranks spin ok, but not great. I have not taken the bearing cups apart...I am chicken because of the "Do Not Disassemble" sticker on them.

Here are my questions:
How freely do your cranks spin? One revolution, two...?

Has anyone installed Phil Wood cartridge bearings in their XT bearing cups? Was it worth it?

Any ideas on the brown grease? Do you think it could be from water coming down the seat tube when I wash the bike?

 

[Bikezilla]

Rebuilding the cartridges are NBD:

I have no idea how many turns I get. The XTRs spun quite freely. The repacked XTs turned more slowly but that has more to do with the grease thickness than anything else. I would imagine it would spin more freely after the new super thick grease I used gets a few rides on it.

I would think the best way to tell if yours need repacking/replacing is to see if they turn smoothly, w/o much resistance. If they feel crunch/gritty the grease is contaminated. If they feel notchy the bearing races may be indexed and will have to be replaced.

As for the source of contamination, it may not be from the seat tube. Not all models have a open connection between the ST and BB. The 5 Spot for example does not. One person had found a bucket full of sand in his BB but his ST did not connect. Turns out his down tube did have a vent hole into the BB shell, and he rode w/o bolts in the lower bottle mounts. The other thing to be mindful of is to avoid using a powerful water stream directly on the bearings, this can force water and dirt in.

 

[cutthroat]

Pretty much in agreement with BZ, the bearings can easily be cleaned and repacked with new grease. In fact, the super-durable high tech PLASTIC bearing cover accidentally popped off one of my bearings when I was pulling the BB spindle out for some chainring work. It simply snaps back on, but I fail to see how these plastic covers provide much of a seal. Anyway - rant aside, if the bearings run smoothly just regrease them and reinstall. As an extra measure of protection I slather grease all around the outside of the bearing housing, reinstall and wipe the excess off the BB shell and surrounding parts. The number of free spins is not really important, this is not a highspeed rotation part like a hub. If it's not gritty you're home free. I have heard that RF bearings are somewhat better sealed but haven't seen them myself. Don't know anything about Phil Wood's. I have seriously departed from using a hose on my cleanings. I now use a spray bottle with soapy water and just rinse gently with the hose on parts that don't rotate. I keep all spray away from the BB, fork and shock seals, and hubs.

 

[Bikezilla]

I figure these seal as good as anything commonly available. (I don't know anything about the PWs)

There is a thin split rubber gasket that rides on the inside of an interlocking flange. That and the grease packed around the inner cover seal, seem to protect the bearings pretty well. There is also that big plastic outer seal and any grease you might pack there.

In the pic above, the black set are year-old + XTR bearings. The grease you see in it is factroy stuff. Clean as a whistle after many rides and washes. Even my XT bearings didn't show dirt in the grease, but somehow some grit got in the race. I'm still confused how that could happen w/o any getting caught outside the races.

 

[CyclingJunkie]

Thanks for the good info. I should have caught the fact that my seat tube is blocked from the bottom bracket. That is obviously not the issue.

I think I might have a tiny bit of grit in the bearings but I need to buy some waterproof bearing grease before I take the bearing cups apart. I can barely hear it when I spin the cranks. I may be the guinea pig and try some Phil Wood bearings too simply because I have heard great things about their longevity.

From the Phil Wood web site:
"Bearings with an "X" in the Part # have seals the same as those specified in the highest quality submersible motor/pump bearings"
The part # for Shimano XT/XTR/DuraAce has the "X" in it.