Advertise on Bikeforums.net



User Tag List

Results 1 to 10 of 10
  1. #1
    Senior Member
    Join Date
    Oct 2006
    Location
    Fishers Indiana
    My Bikes
    Longbikes Slipstream
    Posts
    311
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Hub cartridge bearing, acceptable axial clearance

    I was replacing a worn out rear hub bearing and noticed that the replacement bearings left a slight axial clearance with the hub when secured to the axle -- about 0.020-0.030 -- which meant the hub could potentially slide that amount side to side during cornering or other side loading. Not liking that, I made a shim to go underneath the bearing on one side, but not having anything to really tune in the thickness, the best I could do was about 0.005 or less gap, but this time between the bearing and the step on the axle. Anyone have any guidance or a reference about how much clearance or interference is acceptable in a fit like this? Made a couple pics to try and explain it better.



    Longbikes Slipstream

  2. #2
    Elitist Troglodyte DMF's Avatar
    Join Date
    Jun 2006
    Location
    Dallas
    My Bikes
    03 Raleigh Professional (steel)
    Posts
    6,887
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    You're fine with the shim; 0.005 is pretty small and will disappear when the quick-release is tighened. BTW, how did you measure those clearances? Those are hard spots to get to.

    Yes, I think your concern was well-founded. Are the replacement bearings narrower than the originals?
    Stupidity got us into this mess - why can't it get us out?

    - Will Rogers

  3. #3
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    25,260
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Could the replacement bearing be seated deeper into the hub shell and the extra space taken by an external shim or can you thread the cone in further and add a washer under the locknut to keep the locknut spacing correct?

  4. #4
    Senior Member
    Join Date
    Oct 2006
    Location
    Fishers Indiana
    My Bikes
    Longbikes Slipstream
    Posts
    311
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Replacement bearings were identical to worn ones coming out. Who can say what was original?

    Measurements were with an indicator on the 0.020-0.030 because I could locate and read externally. Measurements were stacked up to calculate the 0.003-0.005 internal gap.

    Figures given are with bearings seated all the way, external shims won't help with the bearing gap and the dropout width is no problem. There is no cone on a cartridge bearing and while I could torque down the lock nuts to close that last 0.005 gap, I don't want to do it because its a ball bearing in a race and preload is normally only used/spec'd for cone/roller bearings.
    Longbikes Slipstream

  5. #5
    Space Dust
    Join Date
    Jan 2008
    Location
    KC Metro
    My Bikes
    Old DF
    Posts
    261
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Nice pictures!

    You need some clearance for differential thermal expansion rates in the materials otherwise expansion can take up all of the slack and put enormous axial loads on the bearings causing them to heat up more and fail.

    It looks like your current setup will quickly load the bearings and cause failure.

  6. #6
    Senior Member
    Join Date
    Mar 2008
    Posts
    4,136
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Wilbur Bud View Post
    I was replacing a worn out rear hub bearing and noticed that the replacement bearings left a slight axial clearance with the hub when secured to the axle ... Anyone have any guidance or a reference about how much clearance or interference is acceptable in a fit like this? Made a couple pics to try and explain it better.

    I'd be really wary about this setup. The type of cartridge bearings used in bike hubs really do very poorly when faced with an axial load.

    From:http://www.skf.com/portal/skf/home/p...newlink=1_1_13

    Axial load carrying capacity

    If deep groove ball bearings are subjected to .. axial load, this axial load should generally not exceed the value of 0,5 C0. Small bearings (bore diameter up to approx. 12 mm) .. should not be subjected to an axial load greater than 0,25 C0. Excessive axial loads can lead to a considerable reduction in bearing service life.



    Which, if I've read the charts correctly would mean that an axial load of about 500 N would be bad news for a probable bike bearing. How hard do you think your QR closes?

  7. #7
    Elitist Troglodyte DMF's Avatar
    Join Date
    Jun 2006
    Location
    Dallas
    My Bikes
    03 Raleigh Professional (steel)
    Posts
    6,887
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    dabac has it right, in principle.

    But this raises a corollary question. If the distance between the axle flanges (where the inner bearing race would seat) is greater than the distance between the hub inner faces (where the outer bearing race would seat), then there's no way to properly locate the outer races. Drive the shell too deep or leave it too shallow, you've introduced axial load too. (Assuming the shells are press-fit.)

    The reason I preferred the shim is that a dislocation of .005 is better than a dislocation of 0.030.

    How tight are the shells in the hub?

    If the shells can float I think I'd leave the shims out.
    Last edited by DMF; 06-11-08 at 10:21 AM.
    Stupidity got us into this mess - why can't it get us out?

    - Will Rogers

  8. #8
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    25,260
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Wilbur Bud View Post
    There is no cone on a cartridge bearing and while I could torque down the lock nuts to close that last 0.005 gap, I don't want to do it because its a ball bearing in a race and preload is normally only used/spec'd for cone/roller bearings.
    I understand that cartridge bearings don't use "cones" the way loose ball hubs do but they normally have a sleeve nut that fits pretty much the same way and acts as a bearing retainer and side-clearance adjuster. I used cone in a generic sense.

  9. #9
    Senior Member
    Join Date
    Sep 2007
    Location
    Gaseous Cloud around Uranus
    Posts
    3,230
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Sounds like there is an offset difference between the inner and outer races,between new and old bearings.Put a straight edge across the races on new and old bearing and check for an offset on one bearing or the other.If both bearings(new/used are flat across the races,check the radius on the races to see if the radius is keeping the the bearing from seating flat against the hub or the axle flange.
    Everything should be as simple as possible...But not more so.---Albert Einstein

  10. #10
    Senior Member
    Join Date
    Mar 2008
    Posts
    4,136
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DMF View Post
    If the distance between the axle flanges (where the inner bearing race would seat) is greater than the distance between the hub inner faces (where the outer bearing race would seat), then there's no way to properly locate the outer races. Drive the shell too deep or leave it too shallow, you've introduced axial load too. (Assuming the shells are press-fit.)
    If the press fit between outer race and hub is tight enough to prevent the hub from sliding back & forth there's no need for the outer race to bottom out against the bottom of the hub bearing seat.
    Actually, since the bearing sucks at dealing with axial load there's not much point in having the hub being able to transfer something that the bearing can't handle.

    The inner race needs to be supported by the axle to withstand the compression added by the QR, but since the whole design is based around the theory of no axial loads on a bike wheel the axial support of the outer race becomes pretty much a non-issue.

    Personally I've had my doubts about this theory for quite awhile, bearings in cartridge hubs seems to last significantly shorter than the old-style cup&cone bearings.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •