Frozen Chorus External BB Bearings - long life?

Discussion in 'Cycling Equipment' started by richardliebert, Feb 2, 2010.

  1. richardliebert

    richardliebert New Member

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    The external bearings in my 2 year old Chorus carbon cranks froze. I ordered new Campy bearings and a new Campy bearing removal/installation tool, so the repair is not going to be a problem. The problem is I thought external bearings were supposed to have a long life. I don't think these bearings have more than 3K on them. What are other peoples experiences with external BB bearings?
     
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  2. tafi

    tafi Member

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    Define "long life"....

    I've seen some that were flogged after much less than 2 years, whilst mine (chorus) are still going 4 years later. I do regularly (every month or two) pull off the cranks and check the bearings and cups. I made the decision to buy the tools along with the groupset.

    I may be wrong but I think campagnolo uses SKF bearings (or if not, SKF equivalents can be used).

    Two issues unique to campag UT cranks which I have noticed are:

    1) The installer must make sure that the bearings are aligned in the cups corectly when the cranks are installed. This is already done on most other BB cups.
    2) There is a lot less seal drag in campag cranks compared to others. They are the free-est spinning external bearing cranks I have ever seen. If this means that there is less sealing, then I am repared to put up with that if it means that my cranks spin as freely as they do.
     
  3. BikingBrian

    BikingBrian New Member

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    +1 on what Tafi said.
    Also, *IF* they're installed correctly and bb faces are parallel, no problems.
    My own experience - I wasn't able to have my bb shell faced locally (no LBSs), so the bearings wore out in a few weeks :eek: My external bb experiment is over, I've gone back to square taper, which is as reliable as it ever was:)
     
  4. richardliebert

    richardliebert New Member

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    Thank you for your opinions, I hope to see more posted over time.

    I'm guessing my bottom bracket is faced correctly, it did last 2 years. I did not have it checked when I converted to external bearings, but assumed it would be good from the factory, it's a SEVEN, they are pretty good at building frames. I have sent an e-mail to SEVEN asking them for an opinion.

    My frozen bearings definitely show signs of rust. My guess is water got in and trashed the bearings. I ride in the rain/snow, yes snow, and use the hose often for cleaning, I know, shame on me.

    In retrospect, the bearings cost about half of what a chain costs, why not replace them every year.

    Am I crazy?
     
  5. dhk2

    dhk2 Active Member

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    My experience has been that contamination with dirt, sand or moisture is what kills bb bearings, not mileage. My frame uses FSA pressed-in bb bearings, and they are just conventional "sealed" cartridge bearings with dust caps over them, meaning they aren't really sealed.

    After riding 500 miles on the dusty/gritty roads of New Mexico and Colorado last summer, found the bb bearings had packed up with only 3K total miles on them. The previous two sets of bearings lasted 10-12K miles, but that was here on relatively clean roads.

    The new Chris King sealed BB, with real seals and grease fittings, might be the answer for those who ride in rain and dust a lot and are tired of replacing BB bearings. They are expensive but seems to me they could last a very long time.
     
  6. alienator

    alienator Well-Known Member

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    Facing the BB really should be considered a necessary step for any external bearing cranks. It's easy enough to have done, and it should be cheap to have done. I certainly wouldn't assume that the BB was faced properly at the factory. Bearings don't like being loaded in a way for which they weren't designed, and that's what happens if the faces of a BB aren't parallel.

    As for seal drag, it shouldn't even be a consideration. Seal drag is constant (excluding wear on the seals). Consider the miniscule amount of force required to turn a crank. That wee bit of force won't impact performance in any noticeable way and possibly not in any measurable way.
     
  7. tafi

    tafi Member

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    The force of seal drag is constant but the power loss resulting from it will rise linearly with shaft speed.

    The fact that it is there at all means that it must affect the system. The question is how much?

    So if I pull out my calculator.....

    If it takes a 20g weight hanging off a horizontal crank arm to just make it move (overcome friction) then the loss is of the order of 0.5W at 100rpm. Note this is a ballpark figure resulting from a resonable guestimate.

    So you are right, it isn't very much. But then some people worry about shaving 5g from a bottle cage (equivalent to 0.03W at 20kph on a 10% incline).

    But i digress.....
     
  8. alienator

    alienator Well-Known Member

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    I'd be surprised if seal drag caused a 0.5 W loss at 100 RPM. I think I can test that. I'll report the result in a day or two. Experiments are always fun.
     
  9. Peter@vecchios

    [email protected] New Member

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    Unfortunately, not unusual. Campagnolo bearings are sealed on only one side and if installed w/o loads of additional grease, this can happen. Prepping the frame is essemtial, as has been mentioned. I also recommend using 'Wheels Manufacturing' Campagnolo type bearings. They have seals on both sides. Take the seals off, grease in there and replace the seals then install. Plus grease around the bearings, inside the cups between the wavy washer.
     
  10. dhk2

    dhk2 Active Member

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    My thoughts on bearing seals would be that it's worth 0.5w to have a bb that lasts without expensive replacements. Plus, with the poorly-sealed bearings, I've ridden a lot of miles with higher friction before realizing the bearings were shot...or being able to get replacements.

    Believe a lot of this gets down to where and how you ride, and how much time and money you're willing to devote to maintenance to get "race bike" performance. It's nice to have cranks that spin freely, but if they pack up after the first good rain ride on gritty roads, or after a couple hundred miles of riding on dusty/sandy roads out west, then maybe not so good.

    I'll have to try some measurements here too, after our little Weds morning ride. The 4C temps shouldn't warm up the grease too much :)
     
  11. randochap

    randochap New Member

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    My experience (working at shop and with many clubmates) is that external bearings do not wear as long as traditional bearing and internal sealed cartridge BBs.

    Preparation and maintenance mentioned above is critical to extending external bearing systems.

    I'm disinclined to use them on a bike intended for long distance events.
     
  12. richardliebert

    richardliebert New Member

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    Wonderful web site, thank you for your comments.

    As a side note, I would never use Mavic Kysrium wheels on a long distance event. One broken spoke leaves you on the side of the road. Been there, done that.
     
  13. alienator

    alienator Well-Known Member

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    I wouldn't use Ksyriums for anything.

    As for external bearings or even internal/integrated headsets, I think they're perfectly fine for long distance events. All that is required is having done proper maintenance before and knowing the state of said bearings. Perceived risk is not the same as actual risk and is almost always greater than actual risk.
     
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