Threaded bottom bracket problems- Mtbr.com
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  1. #1
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    Threaded bottom bracket problems

    I have a 2019 Stumpjumper alloy comp 12 speed that I bought brand new in November 2019 (it was a year old model still brand new at my LBS) it came with a threaded SRAM DUB bottom bracket.

    After about 500 miles of riding (I am mainly a road cyclist), the drive side bottom bracket came loose. I stopped riding as soon as I noticed it. When I got home, I removed the crank and attempted to tighten the crankarm, but the bottom bracket threads in the frame were stripped.

    I did not understand how it could have happened - only 500 miles on it, I have never replaced the bottom bracket myself. Basically, it must’ve came loose because of something the shop did.

    Luckily, my LBS filed a warranty claim and Specialized is sending me a carbon Stumpjumper frame (there were no alloy frames available) for no extra cost. Needless to say, I am extremely pleased with Specialized.

    However, I am not so pleased with my LBS. I think it is their fault the original bottom bracket came loose and stripped the threads, and this is not the first time something my LBS tightened has came loose. On my road bike, my LBS forgot to tighten the brake caliper tight enough to the frame and the whole front disc brake caliper came loose on the form shortly after buying the bike.

    Anyways, this whole situation has made me loose confidence in threaded bottom brackets. I own a Park Tool TW-6.2 torque wrench and have all the appropriate tools, so I trust my ability to torque things down properly. However, I am still afraid that the bottom bracket could come loose and/or somehow the threads in my NEW carbon warranty Stumpjumper frame could get damaged.

    I just want someone’s opinion on possibilities for why my Stumpjumper alloy bottom bracket threads got stripped, and opinions on the robustness/durability of threaded bottom brackets. As of now, I am more comfortable with press fit BB’s, but I want to trust threaded BB’s again.

    Thanks,

    John

  2. #2
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    It was never torqued properly.

    Why do you think it will still loosen if properly tightened to torque spec?

    I would have re-tapped the shell and shredded on the alloy.

    Torque properly and enjoy your bike worry free.

  3. #3
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    Quote Originally Posted by JohnV2000 View Post

    ...However, I am not so pleased with my LBS. I think it is their fault the original bottom bracket came loose and stripped the threads

    I wouldn't assume that, lots of threaded bb's have been improperly torqued and/or ridden loose without causing any damage. Sounds to me like the frame might have been defective.

    Yours was an unusual problem, threaded bb's aren't susceptible to stripping out. Specialized and your bike shop are taking care of you, enjoy!
    I brake for stinkbugs

  4. #4
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    Quote Originally Posted by Velocipedist View Post

    I would have re-tapped the shell and shredded on the alloy.


    Really? Even with a new frame that's eligible for warranty? I wouldn't consider it regardless but without seeing the damage it's unknown whether or not there was enough metal left to tap anyway.
    I brake for stinkbugs

  5. #5
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    Never used a torque wrench on a threaded BB, never had one come loose. I would say it was a defective frame or BB or installation (cross threaded destroying the threads).
    The design of the BB is it will tighten as you pedal, so I would guess something else went wrong. Take the warranty and ride on.

  6. #6
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    when I worked in my last shop, our standard procedure was to remove cranks, remove threaded BBs, clean out the crappy grease in there, treat the threads with a dab of Loctite 242, and torque the cups back in. I think 29 foot-pounds was appropriate on most of them. that keeps the cups from backing out, allows them to be removed with a little muscle when the time comes, and prevents moisture from getting in there. I worked in one shop that did that, and several other shops in years before that who would never even think of taking that kind of time and care with a new bike. unfortunately, most bike shops don't take that kind of care.

    if there was something wrong with the frame, a good shop that really inspects bikes would have at least checked the torque on those cups and noticed that one was loose, or the cup would have stripped out in the stand. there's no way to know what was wrong at this point, so it could be the shop's fault for not checking or Spec's fault for making a faulty frame.

    the threads could probably be re-taped and that frame could be rescued from the recycle bin, but the manufacturer and the shop would have a liability issue on their hands after that.

  7. #7
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    My Enduro came mostly assembled, including the cranks/bb, so it's likely the bike came that way. I don't think it's realistic to expect a shop to disassemble and rebuild a brand new bike, but maybe some do, idk.

    Since it was my bike I did take it apart and reassemble, and I can say that many fasteners were either too loose or too tight.

  8. #8
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    Quote Originally Posted by davec113 View Post
    My Enduro came mostly assembled, including the cranks/bb, so it's likely the bike came that way. I don't think it's realistic to expect a shop to disassemble and rebuild a brand new bike, but maybe some do, idk.
    I built hundreds of bikes at that shop. every threaded BB was checked and torqued. it's not that hard, some shops just have poor procedures.

  9. #9
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    It does sound like the frame was defective. I've never had any real problems with threaded or PF BB's.

    But, I tend to "preflight" my gear. Heck, I even check tightness on lug nuts every time a shop rotates tires or replaces summer/winter tires on cars.

  10. #10
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    Wait, so if a tech left something loose on your car would you lose confidence in cars?
    Ripley LS v3
    OG Ripley v2 handed down to son

  11. #11
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    I don't think it's too likely the lbs even installed the bb. I'd bet a dozen donuts that the bike comes with the crank already installed and all the shop does is install the pedals. This is Specialized and they are making it right by upgrading you to carbon. when you get your bike back, go over it yourself and make sure everything is attached properly (nobody does this). The lbs should do this but you know, they are busy selling bikes.
    2015 Santa Cruz 5010 C

  12. #12
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    Quote Originally Posted by Jetta2010 View Post
    I don't think it's too likely the lbs even installed the bb.
    I am certain they did not install the BB. bikes come in boxes with the BB and cranks pre-installed. however, the bike shop should at least check the torque on the BB cups. if the frame was defective, it would have stripped out in the stand before the bike even went to the sales floor. if it was just not tight enough, testing it would have driven the threads home and this would not have been a problem.

    however, OP got an upgraded frame out of the deal, so that's not too shabby!

  13. #13
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    Quote Originally Posted by JohnV2000 View Post
    However, I am not so pleased with my LBS. I think it is their fault the original bottom bracket came loose and stripped the threads, and this is not the first time something my LBS tightened has came loose. On my road bike, my LBS forgot to tighten the brake caliper tight enough to the frame and the whole front disc brake caliper came loose on the form shortly after buying the bike.
    None of this is on the LBS. The bike came from the Specialized factory with the BB installed. Technically the LBS should not even have to check it.

    Normal procedure before going on a ride is to check over the components on your bike yourself and not rely on the LBS.

    You have a long winded posts that is a nothing burger.

  14. #14
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    Quote Originally Posted by mack_turtle View Post
    I am certain they did not install the BB. bikes come in boxes with the BB and cranks pre-installed. however, the bike shop should at least check the torque on the BB cups. if the frame was defective, it would have stripped out in the stand before the bike even went to the sales floor. if it was just not tight enough, testing it would have driven the threads home and this would not have been a problem.

    however, OP got an upgraded frame out of the deal, so that's not too shabby!


    I've worked at a bunch of shops and none of them have pulled the crankarms off to check torque on bb's. It has never caused any real issues and to my knowledge no bb shells were ever trashed due to that procedure, or lack thereof.

    Most likely something was wrong from the factory (not just improper torque) the bike shop missed it during assembly and the OP got a carbon frame for the inconvenience. Like you said, not such a bad deal.
    I brake for stinkbugs

  15. #15
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    Touche, goods points.

    My calculus was mostly minimizing downtime from riding. As you rightly point out if there wasn't enough shell material left / obviously defective I concurr with warranty as well.

    If retapping is all it needed, I would do that regardless of warranty because I would rather ride. My old Uzzi required a dremel to build it up, tapping/chasing threads is minor if it means riding sooner than later.

  16. #16
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    Just to be clear, I am very satisfied with how this problem was resolved. A new carbon frame is awesome, and Specialized has been great in this process.

    Also, I wasn’t in a huge hurry to get the bike fixed since I am mainly a road cyclist, I just MTB once a week or so. Also, I have a spare SS MTB and a gravel bike that I take on trails. However, I am still glad to be getting my Stumpjumper back.

    As for what someone said about it not being the shop’s fault, while I can understand that, I find it absurd to even suggest that it’s a customers job to make sure the bottom bracket is tight. Sure, I have the appropriate tools to do it, but I bet a majority of customers do not have the tools and/or knowledge to check a bottom bracket. In my opinion, when paying $3,000 or more for a bike, a bike shop should at least inspect the parts to make sure they’re properly installed.

    Like I said before, I am very happy with how this was resolved. However, I feel this issue should’ve been either caught by my LBS in the first place or totally avoided by initial proper installation. It’s not the customers job to buy speciality tools to check BB tightness.

  17. #17
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    Stick to being a roadie. I think it better suits your personality.
    Just like a raindrop, I was born to fall.

  18. #18
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    Quote Originally Posted by JohnV2000 View Post
    Like I said before, I am very happy with how this was resolved. However, I feel this issue should’ve been either caught by my LBS in the first place or totally avoided by initial proper installation. It’s not the customers job to buy speciality tools to check BB tightness.

    True in a perfect world perhaps but mistakes happen eh? You've never made one?
    I brake for stinkbugs

  19. #19
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    [QUOTE = "However, I am not so pleased with my LBS. I think it is their fault the original bottom bracket came loose and stripped the threads, and this is not the first time something my LBS tightened has came loose. On my road bike, my LBS forgot to tighten the brake caliper tight enough to the frame and the whole front disc brake caliper came loose on the form shortly after buying the bike".

    Did you ask your LBS who installed the bottom bracket? Might steer your finger pointing in the right direction.

  20. #20
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    Quote Originally Posted by JohnV2000 View Post
    As for what someone said about it not being the shop’s fault, while I can understand that, I find it absurd to even suggest that it’s a customers job to make sure the bottom bracket is tight. Sure, I have the appropriate tools to do it, but I bet a majority of customers do not have the tools and/or knowledge to check a bottom bracket. In my opinion, when paying $3,000 or more for a bike, a bike shop should at least inspect the parts to make sure they’re properly installed.

    Like I said before, I am very happy with how this was resolved. However, I feel this issue should’ve been either caught by my LBS in the first place or totally avoided by initial proper installation. It’s not the customers job to buy speciality tools to check BB tightness.
    The bike shop gets the bike in from the factory with the BB installed. They aren't going to check the BB before displaying it on the floor. The most they are going to do is slap on the wheels and handlebar and make sure it shifts properly and that the brakes work.

    And before you go out riding on road or MTB...you should always check over your bike.

    Your rant is worthless and you will not receive any sympathy here.

  21. #21
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    Quote Originally Posted by prj71 View Post
    And before you go out riding on road or MTB...you should always check over your bike.

    Your rant is worthless and you will not receive any sympathy here.


    Do you check the torque on your bb cups before every ride? Agree it's not worth ranting about, $hit happens.
    I brake for stinkbugs

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