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  1. #1
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    powertap bearings - are these worn?

    :::EDIT:::
    SOLVED: current or future powertap owners may want to remember this thread.
    :::/EDIT:::

    I was cleaning my bike tonight, I had the wheels off when i noticed that the bearings on the rear hub don't seem as smooth as I think they should be. keep in mind, im no expert, that's why im posting here. The hubs have 3200KM/2000Miles on them. with the wheels off, when I turn the shaft with my fingers it's not perfectly smooth. It's hard to describe what im talking about but it's a slight "bump" every could degrees of turn. I can't hear any noise and there isn't any play. My front wheel by comparison is super smooth!

    again, its very minimal I'm not sure if this is just a characteristic of the powertap hubs or something else.
    Last edited by sixteenornumber; 08-06-12 at 05:18 AM.

  2. #2
    bike whisperer Kimmo's Avatar
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    It's a characteristic of cartridge bearings; you can't adjust them, and any crap that gets in there stays in there unless you press them out and painstakingly disassemble them.

    The slight roughness you're talking about could be slightly tight bearings (a good thing), poor alignment of the hub (doubtful), or grit in the bearings. Your fingers should be able to tell you if it's a matter of geometry or contamination.

    Either way, no big deal.

  3. #3
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    A sharp grindy (homemade word, but you know what I mean) bump is dirt or wear, most likely dirt. But a softer bump may be a magnetic field issue. This is normal in generator hubs, but I don't know if power tap uses magnets for power and position. Someone with a power tap can confirm if they have the classic magnetic pulse.
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  4. #4
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    Quote Originally Posted by FBinNY View Post
    A sharp grindy (homemade word, but you know what I mean) bump is dirt or wear, most likely dirt. But a softer bump may be a magnetic field issue. This is normal in generator hubs, but I don't know if power tap uses magnets for power and position. Someone with a power tap can confirm if they have the classic magnetic pulse.
    The "Powertap" isn't a generator hub, it's a power/torque/wattage measuring hub. I believe it contains a strain gauge and some means of rotational speed determination to calculate power input and a transmitter to send the data to a handlebar mounted readout.

  5. #5
    coprolite fietsbob's Avatar
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    If in doubt .. cartridge bearing assembles all generally have a number imprinted in the seal.

    like (example) 6001 .. you can order new bearings from many sources, that sell bearings.
    not narrow sources like from power tap, thru the bike shop you got the hubs from..

  6. #6
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    Quote Originally Posted by HillRider View Post
    The "Powertap" isn't a generator hub, it's a power/torque/wattage measuring hub. I believe it contains a strain gauge and some means of rotational speed determination to calculate power input and a transmitter to send the data to a handlebar mounted readout.
    I'm aware of that, but wasn't sure if it used an induction circuit for position. If so, I wouldn't expect strong magnets, but I don't know what the OP is feeling either.
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    Quote Originally Posted by Kimmo View Post
    It's a characteristic of cartridge bearings; you can't adjust them, and any crap that gets in there stays in there unless you press them out and painstakingly disassemble them.

    The slight roughness you're talking about could be slightly tight bearings (a good thing), poor alignment of the hub (doubtful), or grit in the bearings. Your fingers should be able to tell you if it's a matter of geometry or contamination.

    Either way, no big deal.
    now that you mention it, it kinda feels like it's "too tight." I've only ridden in water a had full of times and the seals on the powertap hubs seem to be quite good.

    thanks for the help

  8. #8
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    Quote Originally Posted by fietsbob View Post
    If in doubt .. cartridge bearing assembles all generally have a number imprinted in the seal.

    like (example) 6001 .. you can order new bearings from many sources, that sell bearings.
    not narrow sources like from power tap, thru the bike shop you got the hubs from..
    I am in doubt... I already found the specs of the bearings and will prob order some today.

  9. #9
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    If you want to bother you can pop the seals off and flush them with solvent, dry them and grease them. If not this is a good source:http://www.enduroforkseals.com/id138.html You should need the 61000 2RS if they are the same as a friends.

  10. #10
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    If these are 6001 or similar deep groove radial bearings be very careful not to apply a preload when adjusting the hub.

    Preloading is correct and necessary for angular contact bearings like classic cup/cone hubs. But radial bearings are already preloaded and excessive side load will jam the balls against the sides of the tracks, materially shortening the life of the bearing.

    Adjust them so that any play at the rim is taken up, and no tighter. If in doubt, a bit loose is better than a hair tight (the opposite of what angular contact bearings want).
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    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  11. #11
    coprolite fietsbob's Avatar
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    Angular contact sealed bearings,, will act like cup and cone. for adjustability
    radial contact , not so good an idea to side load them..

  12. #12
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    Quote Originally Posted by davidad View Post
    If you want to bother you can pop the seals off and flush them with solvent, dry them and grease them. If not this is a good source:http://www.enduroforkseals.com/id138.html You should need the 61000 2RS if they are the same as a friends.
    I pulled the bearings getting ready to pull the seals off. I spun each bearing in my fingers but felt not harshness what so ever! I reinstalled everything and it came back. After reinstalling the wheel bearings I gave the shaft that holds the cassette a VERY VERY light tap with a plastic hammer. The kind of tap that wouldn't hurt if I hit your head. the harshness was gone and it felt like a new wheel again. I I still don't know exactly what the problem is or was but it appears to be gone now. My guess is that it's possible to install the press fit cartage bearings too tightly. I'm going to do ~100 miles over the next couple days and report back in. stand by for results.

  13. #13
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    Everything is looking GREAT! the bearings i was having trouble with (still using the same ones) were factory installed. As far as I can tell, either they were installed to tightly, they worked them selves in that way or something else.

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