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Thread: Bottom Bracket ID Oversized or Crank Spindle Undersized?

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    Default Bottom Bracket ID Oversized or Crank Spindle Undersized?

    I was so proud of myself for finding a BB click that appeared on medium to light efforts, especially at higher cadence. I have a 2021 Trek Domane with a Praxis T47 BB and 105 crank. I removed the crank and found faint smudges on the spindle and bearing inner race where they meet and where the power stroke would cause pressure. Makes sense, right? Tolerances were looser than ideal, causing movement and metal on metal ticking.

    A light coat of HEAVY grease(roofing tar consistency) cured the problem for 1000 miles. Then it fixed it for 500 miles and now it seems to come back within 100 miles. I see where this is going and I will need to address this with parts. What is more likely to be out of spec, the Praxis BB or the 105 Crank? I have digital Vernier calipers but I doubt they will have the precision to find the issue.

    Anyone run into this that can share their experience before I start firing the parts cannon at the bike? Thankfully these parts are pretty cheap...

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Not a fan of Praxis bb’s they are like the Bullseye’s.
    Tim Campen

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Grease has zero strength, it's just going to quiet the movement for a while and you don't want movement. Ditto with teflon tape or pipe dope.

    This is a job for your Trek dealer (because they have excellent warranty support).

    Outside of that, like if you're not the original owner, I'd go at it one of two ways. One is find a composite frame expert (or become one) and put a schmeer of reinforced epoxy on those threads and re-tap. Two is some green Loctite after some soul searching about what it's gonna look like the next time I have to remove those cups. Maybe try Loctite PST 567 as an interim, likely to fail but better than grease, attempt.

    And Praxis, no thanks. Maybe that's a third option, try a BB from a different manufacturer (I'm prejudiced from a bad experience with their chainrings).
    Trod Harland, Physical Educator

    Not everything that is faced can be changed, but nothing can be changed until it is faced. — James Baldwin

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    The Trek frame?

    Sorta kidding.

    Shimano's crank is least likely to be out of spec I'd think. Try another brand's BB, like WheelsMFG or Chris King. Then if it recurs, contact Trek.

    Edit: I must type replies in a time-space vortex. How did Todd's post happen 17 minutes ago when it wasn't there when I started typing?

    Anyway, yeah, flex. Something is allowing side to side flex. Threaded sides of a BB are supposed to stay inline with parallel surfaces. This one sounds like it is not. Trying a different BB design would potentially offer reinforcement to the frame at the BB shell.
    Last edited by j44ke; 03-19-2021 at 10:22 PM.
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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Thanks for the help. This is not the BB90 frame where the bearings sit right on the carbon frame cups. If that were the case, I would follow Trek's guidelines...clean the bearings and replace the frame.

    I was willing to buy a Trek because they make them with a threaded aluminum T47 BB shell now. My BB is a threaded Praxis unit that came with the bike. When the creaking starts again, I will replace the BB with something better.

    Thanks again!

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    And sorry for the misread, your issue is not with the threaded interface, my bad.

    Green Locitite (cylindrical part retaining compound) is worth a shot, as it won’t be such a bear to remove there.
    Trod Harland, Physical Educator

    Not everything that is faced can be changed, but nothing can be changed until it is faced. — James Baldwin

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    So the bb shell is a continuous aluminum tube, not just threaded rings at either end? I don’t understand how there would be any movement at all then.
    Last edited by j44ke; 03-20-2021 at 12:08 PM.

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    My tuppence: Use a C-Bear BB. Not cheap, but they've never failed to sort a problem for me.

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Quote Originally Posted by j44ke View Post
    So the bb shell is a continuous aluminum tube, not just threaded rings at either end? I don’t understand how there would be any movement at all then.
    With the wear marks found it sounds like the movement is between the axle and the bearing - so a different BB sounds like the thing to try first.
    It's not the years, honey. It's the mileage.

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    I just can't imagine a spindle OD being small, or a bearing ID being too large.

    That said, my first call would be to Praxis. Personally, I like them. I like their product, and I enjoy the people that work there.
    -Dustin

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Thank you for the help. I had two rides in silence so the noise should return on my ride this evening, if history is a guide.

    When I take it apart, I will take a few pictures to share here and with Praxis. If I hit a roadblock, the BB will be replaced with something better.

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Trying to catch up. Trek evidently worked with Praxis on the design, because it needed thicker knurled flanges for factory installation. So the bottom bracket shell on a Trek is 85.5mm instead of the normal 86.5mm, with the 1m used up by the extra thickness of the flanges.



    The Trek-Praxis T47 BB is not compatible with standard 86.5mm bottom bracket shells, but standard 86.5mm bottom brackets should be compatible with Trek T47 BB shells that are 85.5mm wide.

    You can read in greater detail here on CyclingTips, but that's the synopsis.

    All this to say that I wouldn't be surprised if that 1mm is perhaps 0.8mm or something, and what is clicking is the central Delrin spindle cover. But that doesn't explain any atypical wear marks.

    Could also be your seat/seatpost clamp.
    Last edited by j44ke; 03-22-2021 at 07:28 PM.
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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    since the noise disappeared with the heavy grease, at least for a spell, I wouldn't suspect the seat/post. and then there's those smudges. anyway. I can't recall this happening to the 105 cranks, but my ultegra developed a little creak/click that was consistent with the de-bonding of the spider we've seen. My faith in hollowtech is shaken. Probably not that, but worth mentioning in the context.
    am I the only Marvin?

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Is the bottom bracket in this application a bare bearing or is there some kind of plastic sleeve between the bearing ID and the crank spindle like a typical Shimano? The later has some give to it to allow for frame misalignment. Does the crank slide into the BB with ease or does it start to bind when it gets to the other bearing? If it does, that could be a sign the the bearings are not running concentrically. That could be in the bottom bracket itself or the frame, hard to tell from afar. If the bearings are bare, putting some loctite 680 on them would likely solve the creak but would not fix the bearing drag that inevitably comes with this condition. It would be wise to measure the faces of the BB shell for parallelism as best you can as that could be the foundation of the problem and it's relatively easy to check.

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Quote Originally Posted by giordana93 View Post
    since the noise disappeared with the heavy grease, at least for a spell, I wouldn't suspect the seat/post. and then there's those smudges. anyway. I can't recall this happening to the 105 cranks, but my ultegra developed a little creak/click that was consistent with the de-bonding of the spider we've seen. My faith in hollowtech is shaken. Probably not that, but worth mentioning in the context.
    Yeah doesn’t sound likely but I have had seat clamps start to pop click after “warming up” 1/3 of the way into a ride. So I’d do something, first part of the ride was quiet, then not quiet. Finally took apart the clamp and lubed whatever contact surface I could find, reassembled and that did it.

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Quote Originally Posted by abbeyQ View Post
    Is the bottom bracket in this application a bare bearing or is there some kind of plastic sleeve between the bearing ID and the crank spindle like a typical Shimano? The later has some give to it to allow for frame misalignment. Does the crank slide into the BB with ease or does it start to bind when it gets to the other bearing? If it does, that could be a sign the the bearings are not running concentrically. That could be in the bottom bracket itself or the frame, hard to tell from afar. If the bearings are bare, putting some loctite 680 on them would likely solve the creak but would not fix the bearing drag that inevitably comes with this condition. It would be wise to measure the faces of the BB shell for parallelism as best you can as that could be the foundation of the problem and it's relatively easy to check.
    Thank you for the insight. This is a bare bearing with a typical 24mm Shimano spindle. When I slide the spindle in or out, it doesn't seem to bind any more than a typical Shimano setup. I will take some pictures of the smudges on the contact point later this week.

    The bike and BB have ~3500 fair weather miles and both bearings still spin very smoothly. If the bearings were out of parallel and had friction inducing alignment issues, would they be rough by now? To measure the parallelism, am I looking for the BB bore to be not perfectly perpendicular to the vertical plane or one of the cups not in the same plane as the other(facing issue-type problem)?

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Quote Originally Posted by houston View Post
    Thank you for the insight. This is a bare bearing with a typical 24mm Shimano spindle. When I slide the spindle in or out, it doesn't seem to bind any more than a typical Shimano setup. I will take some pictures of the smudges on the contact point later this week.

    The bike and BB have ~3500 fair weather miles and both bearings still spin very smoothly. If the bearings were out of parallel and had friction inducing alignment issues, would they be rough by now? To measure the parallelism, am I looking for the BB bore to be not perfectly perpendicular to the vertical plane or one of the cups not in the same plane as the other(facing issue-type problem)?
    You just need to measure the width of the BB at a few different spots. There's enough play in the thread that the BB will take the alignment of the shell when it tightens up.

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Thank you!!

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    I got the annoying clicking back yesterday. I pulled the crank out and took a few pics. The drive side bb has some marks on the outer surface of the bearing I.D. that are suspect. The spindle has similar markings. The non drive spindle pic shows that I am not getting lateral play. BB shell is parallel according to my calipers and the cups are torqued to spec.

    2021-03-30_10-22-24 by Owen Dow, on Flickr
    2021-03-30_10-15-05 by Owen Dow, on Flickr
    2021-03-30_10-16-18 by Owen Dow, on Flickr

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    Default Re: Bottom Bracket ID Oversized or Crank Spindle Undersized?

    Does look like a bit of galling there possibly, but could also be baked-on grease residue.

    Are there spacers on the chainring side of the spindle? Between the bearing and the spider.

    Also looking at the bright surfaces at the ends of the splines on the non-drive end of the spindle. Is it possible the non-drive arm is bottoming out on the splines before the crank is truly snug?
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