Bicycle Mechanics - Pressed in bottom bracket bearings

I just thought I'd check before prying these pressed in bearings out of an old Cannondale bottom bracket cup.

(I can't imagine why they did this - I've replaced tons of separate bearing retainers, but never one pressed-in.)

So - Any problem with just prying these out and replacing with loose 1/4" balls?

http://i254.photobucket.com/albums/hh117/auchencrow/Bike%20Forums/Bearing.jpg

nope, no problem with just prying out that retainer ring. i had the same bottom bracket (on a cannondale!) and i just tossed the pressed-in retainers after servicing the BB.

nope, no problem with just prying out that retainer ring. i had the same bottom bracket (on a cannondale!) and i just tossed the pressed-in retainers after servicing the BB.

Thank you Southpaw!

take a picture of the other side of that retainer will you? It'd be interesting how they made a retainer to hold 11 balls. The fingers must really be narrow.

Can't you just pluck out the old balls and put in new ones?

I suspect that the "retainer" is also part of a dust and moisture shielding system. We're used to the usual plastic or rubber seals but there was a method called "labyrinth sealing" in the old days where they used back and forth direction changes in the path for any dust or moisture to enter the bearing. The advantage to this style being that since there was no actual contact within the seal area there is no drag at all. This may be part of a similar idea depending on what the rest of the parts look like.

take a picture of the other side of that retainer will you? It'd be interesting how they made a retainer to hold 11 balls. The fingers must really be narrow.

no fingers on this retainer ring. the balls are loose. the ring is pressed into the cup and simply prevents the balls from falling out. the balls aren't held in place on the ring itself.


Can't you just pluck out the old balls and put in new ones?

not without first prying out that ring.


I suspect that the "retainer" is also part of a dust and moisture shielding system. We're used to the usual plastic or rubber seals but there was a method called "labyrinth sealing" in the old days where they used back and forth direction changes in the path for any dust or moisture to enter the bearing. The advantage to this style being that since there was no actual contact within the seal area there is no drag at all. This may be part of a similar idea depending on what the rest of the parts look like.

that's possible, altough if that's the function of that ring, it didn't do its job very well on the bottom bracket i took apart. i can see how the ring may prevent water from the seat tube or downtube from splashing onto the bearings from inside the bike frame, but the ring does nothing to prevent dirt or water from getting to the balls from the outside, and in fact i can see how it would trap water between itself and the outer cup wall. IIRC, the BB i rebuilt like this one had no external rubber seal around the spindle.

I think the ring may be a seating-surface for the plastic accordion-type shield that prevents dirt & water from entering from the seat and downtubes. It can also serve as a production-aid in that it allows people to assemble the bike faster without worrying about 11 loose-bearings falling out and running all across the floor.

I ran into this pulling a BB from a Specialized Hard Rock the other day. I just levered the pressed in side out and popped it back in during re-assembly.

I suspect that the "retainer" is also part of a dust and moisture shielding system. We're used to the usual plastic or rubber seals but there was a method called "labyrinth sealing" in the old days where they used back and forth direction changes in the path for any dust or moisture to enter the bearing. The advantage to this style being that since there was no actual contact within the seal area there is no drag at all. This may be part of a similar idea depending on what the rest of the parts look like.

Old days? Labyrinth seals are still around, for the same reasons they always have been. Work great, last a long time, work at high speed.

I'm still riding my 1980's C-record BB with the spirals in the cups. Got over 50k-miles on it. Just overall it once a year and that's about it. :)

Southpaw and Danno pretty much had it right - except there was no accordion seal on this particular bike, and there was a little hard black plastic ring, but since this ring shares the same inner diameter as the cup, it was obviously intended to keep the grease inside inside, rather than contaminants outside out.
This would make a lot of sense if you has a bin full of pregreased cups ready to pop into frames on an assembly line.

- I'll just put new balls into it and I'll be all set!
Thanks all.

http://i254.photobucket.com/albums/hh117/auchencrow/Bike%20Forums/Bearing002.jpg