Quantcast
velospace is about bikes and the people who ride them buy / sell photos random












How-To/Mechanics: BB fail

Bottom of Page

1 to 23 of 23

  1.  
    • CommentAuthortdubs
    • CommentTimeAug 30th 2009 edited
     
    mid skid, i felt a "slip" in my crank/BB area. it felt as if the whole bottom bracket moved within the shell. then as i pedaled forward, it slipped again as if the cranks had to "catch up". i actually ate shit cause the forward momentum carried me over the bars. any ideas what could be happening here? i assume the slipping is the crank-arms within the BB but can't really tell and i'm new to the mechanics of bicycles. i rode around a bit and tried to repeat the problem. if i really put alot of pressure in my skid, it will slip and then if put all my wait on one pedal it will slip forward again. as long as im pedaling forward, everything is fine. its the skid/backpedaling that causes the problem
  2.  
    It's most likely your cog slipping. The same thing's been happening to me lately. I just have a crappy generic stamped steel cog which is probably why. make sure your cog and lockring are good and tight.
  3.  
    cog and lockring,no room for the bb to move
  4.  
    oh and dont tighten it up with a flat head. use the tool that is made to be used on a cog and only a cog
    • CommentAuthortdubs
    • CommentTimeAug 30th 2009 edited
     
    Posted By: carbon fiber15oh and dont tighten it up with a flat head. use the tool that is made to be used on a cog and only a cog


    why not the flat head?
  7.  
    Posted By: tdubsfile:///Users/toddwiege/Desktop/IMG_0890.jpg

    file:///Users/toddwiege/Desktop/IMG_0889.jpg

    Oh jesus.

    Anyway, Todd, since you don't have a bike posted here, and you neglected to mention what you're using, and your photos exist only on your desktop... Well, we just don't know where to start.
    KD is probably right though, I don't know how your BB or crank arms would slip in the way you describe.
  8.  
    By the way, read this thread. 874
  9.  
    It's your cog and lockring. Take it to a bike shop to get it tightened, and while there purchase a chain whip and a lock ring tool, so when it loosens again, you can tighten it yourself. Don't ride it loose or try to tighten it with any other tool or you will fuck it up.
    • CommentAuthortdubs
    • CommentTimeAug 30th 2009 edited
     
    Oh jesus.

    Anyway, Todd, since you don't have a bike posted here, and you neglected to mention what you're using, and your photos exist only on your desktop... Well, we just don't know where to start.


    thanks, Mark....i was posting a couple quick pics to show just that... clearly i'm new at this which is why im on here. i thought the photos were good enough to show what i'm working with. as i said in my original post, and every other post i've placed here, im not a bike mechanic and i'm on here to LEARN.
  11.  
    I'm not attacking you, dude, I'm messing with you. What I was trying to tell you is that no one beside you can see your photos. You'll have to upload them somewhere first. Try photobucket, flickr, picasa, here (via the bike submission tool), etc. Dragging and dropping photos from your desktop doesn't work on forums.
    But again, it's probably not a problem with the front end of your drive train, but instead one with the rear. Take a look at your lock ring and cog first.
    I'm all for being helpful, but sometimes funny things happen and are worth pointing out.
    • CommentAuthorAaron C
    • CommentTimeAug 30th 2009
     
    just cross your fingers that you haven't already fucked your hub beyond repair.
    • CommentAuthortdubs
    • CommentTimeAug 30th 2009
     
    Posted By: tdubs

    file:///Users/toddwiege/Desktop/IMG_0890.jpg

    file:///Users/toddwiege/Desktop/IMG_0889.jpg


    oops... thats what i meant to do. not that it matters now

    http://picasaweb.google.com/twiege/BBPics?feat=directlink
    • CommentAuthortdubs
    • CommentTimeAug 30th 2009
     
    and by fucked up you mean stripped? its a couple years old... the lock ring and cog are Formula. now are these just cheap crappy components or is it normal wear and tear?
  15.  
    Formula stuff is totally fine. But if your cog and lockring are loose, it wouldn't matter if they were Phil Wood, they would be fucked up after enough riding. Don't ride it, take it to a shop and ask them to look at your setup. They probably won't charge you if all they have to do is tighten things up. If you want to do this sort of thing for yourself in the future, ask them to sell you the necessary tools (chain whip and lockring spanner), and ask them to show you how to use them (it's pretty easy).
    Now, if you've stripped the hub (yes, that's the danger Aaron is speaking of), there is no way to repair it safely, you'll have to replace it. There are ways to ... I won't say repair, but ways to make a stripped hub work, but none are smart.
    • CommentAuthorAaron C
    • CommentTimeAug 30th 2009
     
    Posted By: tdubsand by fucked up you mean stripped?


    nah, i meant cock slapped to the point of uselessness.

    and yes i meant stripped. that is what happens when you don't tighten your cog properly. with the exception of the issues with mavic ellipses (which i have no first hand experience with but have been the topic of several threads) everytime i have heard of this happening its because: a) you put your cog/lockring on with a slip-joint pliers and/or a hammer and slotted screwdriver, and b) has resulted in hub thread salad.
  17.  
    The pictures of your bottom bracket don't show us anything.

    My GF had a Formula lock ring on her fixed gear, and I think that thing was made of alloy, and was super thin with only a few threads.

    If you are doing skids and/or riding brakeless, you should replace that cheap formula ring with a stronger lockring like a DuraAce, Phil Wood, etc.
    • CommentAuthortdubs
    • CommentTimeAug 30th 2009 edited
     
    i posted those because.... ah nevermind.


    thanks for the help everyone
  19.  
    this forums probably dead but besides the obvious cog lockring issue, im also thinking depending if your running a square taper bb and some really cheap arms, or just non compatible tapers that dont fit right, you could have possibly rounded out the point of contact on your arms.....just a thought.
  20.  
    That's true, but it's very unlikely that both would have worn out at the same time. Plus, had this been the case, the crank arms would not work as opposites on the same plain. (I'm having trouble describing this, but both would come to rest pointing downward as opposed to pointing in opposite directions.) I thought about his bolts being loose, which would produce that effect as well, but there is no way they would look right when he got off to check out what happened. Had they not looked right he would have said something. Good thought, though.
    • CommentAuthorAaron C
    • CommentTimeSep 3rd 2009
     
    Posted By: suicide_doorsbut both would come to rest pointing downward as opposed to pointing in opposite directions.


    i don't think this could even happen to a bike realistically. i've seen one really horrible case of rounding out the taper of a crank arm--it had about 90* of play in it.

    the bike had become so unrideable though that i don't think it would be possible to totally round out the arm to the point that you have 180* of play.
  22.  
    I had it happen when I didn't tighten my crank bolts enough (because I lacked the appropriate tool...). More what I was trying to say was that the crank arms would not come to rest in their normal 12 & 6 positions.
    • CommentAuthorAaron C
    • CommentTimeSep 3rd 2009
     
    no doubt
    • CommentAuthortdubs
    • CommentTimeSep 4th 2009
     
    it was in fact the lock ring... and is now tight again.

    thanks.

    i look forward to posting another newbie... er, n00b question soon

1 to 23 of 23

  1.  
 


about, FAQ & policies | contact | blog | status | resources | site map | graphic design
© 2005-2009 velospace. All Rights Reserved.