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  1. #1
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    New XT Crankset seems 'sticky'

    I bought and installed the XT external bearing (FC-M770) crankset last week. I have noticed that they feel 'sticky' when freespun by hand.

    For instance, on my old crankset, when they were installed and the chain was disconnected, I could spin the crankarm by hand and they would spin around 5 or 6 times freely. They were entry level Shimano. I forget the model number right now but basically Deores.

    On the new crankset, with them fully installed and the chain disconnected, I see about 1 rotation when I spin them by hand and they feel 'sticky' to me.

    My question is, is this normal? Should the XT crankset feel more sticky than a lower end set and why? If not, what could I have done wrong or could it be a defect?

    TIA,
    Steve

  2. #2
    EDR
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    Make sure you haven't overtightened that little cap that goes over the non drive side arm. It should only be finger tight.

    Assuming your installation is correct and you have not pre-loaded the bearings unintentionally (hard to do with XT), you are likely just feeling the difference between new bottom bracket bearings tightly packed with grease and your old ones, which in all likely-hood, had little or no grease left in them. Cartridge bearings with no grease in them will spin freely. They will also fail prematurely.


    Grease is good. The resistance you feel by hand is not perceivable while pedaling.

  3. #3
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    Quote Originally Posted by se4b4ss
    I bought and installed the XT external bearing (FC-M770) crankset last week. I have noticed that they feel 'sticky' when freespun by hand.

    For instance, on my old crankset, when they were installed and the chain was disconnected, I could spin the crankarm by hand and they would spin around 5 or 6 times freely. They were entry level Shimano. I forget the model number right now but basically Deores.

    On the new crankset, with them fully installed and the chain disconnected, I see about 1 rotation when I spin them by hand and they feel 'sticky' to me.

    My question is, is this normal? Should the XT crankset feel more sticky than a lower end set and why? If not, what could I have done wrong or could it be a defect?

    TIA,
    Steve

    5 to 6 spins is a good target for the XT crankset....try backing off the preset nut, (you have to undo the pindh bolts first), then pulling the nds crank a little bit out then "slowly' while spinning the crank tighten the preset nut...

    You of course want zero play in the crank and you should get there pretty easily.

  4. #4
    Formerly of Kent
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    With a "modern" bearing system, how it spins without any load on it has absolutely nothing to do with how it will perform when you're pedaling.

    Just an FYI...

  5. #5
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    Thanks for the replies gentlemen.

    @EDR - Agreed, this could be just a matter of feel as this is only the second set of cranks I've worked on and the first set was low end as mentioned. I did take the bike out for about 8-9 miles on the sidewalks in the neighborhood and didn't notice any resistance when pedaling. I don't think the cap on the NDS is the issue because there was resistance on the DS crank when the NDS crank wasn't even installed yet. I will keep it in mind though as I'm troubleshooting and putting it all back together. TY.

    @Jeff - I'm not sure what the preset nut or the pindh bolts are. Is the preset nut what screws into the bike frame with the bearings in it, what the instructions call the left adapter? And the pindh bolts, are they what hold the left crank in place on the axle?

    Here is a link to the instructions: http://www.shimano.com.au/media/tech...9830671849.pdf

    I applied grease to the left and right 'adapters and the bottom bracket shell before screwing them in place. Should I apply grease to the inside of the 'inner cover' and the outside of the axle? The instructions didn't mention but it seemed like I should...

    Thanks again guys, you're help and feedback is appreciated.

  6. #6
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    Quote Originally Posted by se4b4ss
    Thanks for the replies gentlemen.

    @EDR - Agreed, this could be just a matter of feel as this is only the second set of cranks I've worked on and the first set was low end as mentioned. I did take the bike out for about 8-9 miles on the sidewalks in the neighborhood and didn't notice any resistance when pedaling. I don't think the cap on the NDS is the issue because there was resistance on the DS crank when the NDS crank wasn't even installed yet. I will keep it in mind though as I'm troubleshooting and putting it all back together. TY.

    @Jeff - I'm not sure what the preset nut or the pindh bolts are. Is the preset nut what screws into the bike frame with the bearings in it,No it is the nut that screws into the crank shaft and holds the left crank arm in what the instructions call the left adapter? And the pindh bolts, are they what hold the left crank in place on the axle?Yes

    Here is a link to the instructions: http://www.shimano.com.au/media/tech...9830671849.pdf

    I applied grease to the left and right 'adapters and the bottom bracket shell before screwing them in place. Should I apply grease to the inside of the 'inner cover' and the outside of the axle? The instructions didn't mention but it seemed like I should...I do but clean up the excess so it doesn't attract dirt

    Thanks again guys, you're help and feedback is appreciated.
    The problem with the preset nut (preload nut??) being to tight is that you have loaded the bearings more than neccessary and they will tend to wear out faster.

    Also if you are only getting 1 or 2 spins it will have more drag, and at the end of a long day I hate drag.

    Also bear in mind that the crank will speed up in the first week or so...

    Still 5 to 6 turns is about right.

  7. #7
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    I have another question. Let's assume I overtightened the right and/or left adapters during the installation. Does that permanently damage them or would just loosening them be ok?

    Thanks,
    Steve

  8. #8
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    Quote Originally Posted by se4b4ss
    I have another question. Let's assume I overtightened the right and/or left adapters during the installation. Does that permanently damage them or would just loosening them be ok?

    Thanks,
    Steve

    By adapters I think you mean the bearing cups that fit into the frame....

    Overtightening those would only be a problem if you stripped the threads.....

    It might be possible that you have caused them to go out of round if the installation tool was not "centered" on the cup....

    Shimano cups are sold complete with the bearings for replacement...

    Yes you could loosen them but I wouldn't bother.

  9. #9
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    http://www.shimano.com.au/media/tech...9830680226.pdf

    Check out the link above. The parts labeled '1' and '2' are referred to as right and left adapters by the docs.

  10. #10
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    Quote Originally Posted by se4b4ss
    http://www.shimano.com.au/media/tech...9830680226.pdf

    Check out the link above. The parts labeled '1' and '2' are referred to as right and left adapters by the docs.

    Yes Dear those are the bearing cups stick your finger in them and feel the bearing go round and round.

  11. #11
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    As I understand it, the bearings can be tightened down into the 'adapters' so I wasn't sure if you meant the adapters themselves or the part inside that tightens down to hold the bearings in the adapter. Since I am a bit ignorant as previously mentioned, I wanted to make sure I understood what you were saying....I'm not your dear though. Thanks.

  12. #12
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    Quote Originally Posted by se4b4ss
    As I understand it, the bearings can be tightened down into the 'adapters' so I wasn't sure if you meant the adapters themselves or the part inside that tightens down to hold the bearings in the adapter. Since I am a bit ignorant as previously mentioned, I wanted to make sure I understood what you were saying....I'm not your dear though. Thanks.

    The bearings are press fit into the bearing cups, there is no adjustment there...

    To preload the bearings the crank is inserted, the left crank mounted...then the preset..preload nut is tighten, gently just finger tight....the tighter then more the bearings are side loaded....

    Then the pinch bolts are tightened...

    If you take the pinch bolts off...

    Then back off the pre load nut out....

    Then wiggle the left crank arm out a bit....

    Now the bearings have zero preload....

    Spin the crank...how many revs do you get....

    Then gently screw in the preload nut...spin the crank...how many spins do you get...

    When you figure it is good clamp down the arm with the pinch bolts...

    Ther you go.

  13. #13
    EDR
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    FWIW cartridge bearings by design are not meant to have ANY preload. That 'pre-load' cap is just meant to help take out the slack when you install the left crank arm. It's purpose is to firmly, but gently slide the arm against the BB while pulling the other side in, all in an effort to ensure there is no slop.

    My point is....FINGER tight is sufficient for the cap, you are not trying to pre-load the bearing like a cup and cone set up. I think jeffscott mentioned to tighten it then loosen it back up. I've never bothered to do that but it's not a bad idea. Tighten it firmly, then loosen. Everything is taught/tight, then lightly finger tighten it back up.

  14. #14
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    I've got the bike on the rack now. I'll post up my findings.

  15. #15
    the catalan connection
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    Also said above.That is what I do, just tighten the preload nut to make everything get together, and then unscrew it half a turn or so.
    "Blessed is the man who, having nothing to say, abstains from giving us wordly evidence of the fact." George Elliot

  16. #16
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    Ok, I removed the chain and it was already better than when I installed it so I guess the 8 or so miles helped loosen things up a bit. I could spin the cranks and get 2-3 spins.

    I went ahead and took them apart, greased the axle and inner cover, and put them back together with less force and only finger tightened the preload nut. After that, I can almost get 5 rotations and still not feel any give or play when I try to move the cranks around with my hands.

    So, I guess all is good now except that I want to ride on them to make sure they aren't loose or anything under stress. And I've decided *not* to sue Shimano for emotional distress.

    :cheers: guys and thanks a bunch for spending your time to help me out on this.

  17. #17
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    Quote Originally Posted by se4b4ss
    Ok, I removed the chain and it was already better than when I installed it so I guess the 8 or so miles helped loosen things up a bit. I could spin the cranks and get 2-3 spins.

    I went ahead and took them apart, greased the axle and inner cover, and put them back together with less force and only finger tightened the preload nut. After that, I can almost get 5 rotations and still not feel any give or play when I try to move the cranks around with my hands.

    So, I guess all is good now except that I want to ride on them to make sure they aren't loose or anything under stress. And I've decided *not* to sue Shimano for emotional distress.

    :cheers: guys and thanks a bunch for spending your time to help me out on this.

    Check them out every couple of weeks...see if you get any side to side play....if you do repeat the above process, the pre load needs a bit of tightening.

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