I just installed a new external bearing bottom bracket. Please Help!

Discussion in 'Road Cycling' started by MrKook, Nov 3, 2010.

  1. MrKook

    MrKook New Member

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    As the post suggests, I just installed a new crankset and bottom bracket with external bearings. The crankset is an FSA K Force compact, and the bottom bracket is the corresponding MegaExo external. My bottom shell measures 70mm. I greased everything up really well and I made sure the cups and internal spacer sleeve thign was installed straight and properly. I wasn't grinding any threads on the way in. Anyway, it turns really smoothly but it doesn't want to spin really freely if I give it a spin (with no chain yet installed). I don;t hear any grinding or feel and bearing ceasing. It's really smooth but my old bracket would spin for about 15 seconds and then come to a rest on the drive side back and forth. So do you believe that something is wrong? Should the crank be able to be spun 30 times around with one push of the crank arm or will it break itself in? I am sorry for the rough explanation. Please ask any questions you need to fully understand.

    Also, I have a 2mm washer spacer but the middle spacer said "68/70mm" and my bottom shell measures 70mm so I shouldn't need that, yeah?

    Thanks in advance.
     
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  2. VCRCBike

    VCRCBike New Member

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    Was your frame faced prior to installation? If not, that could cause drag on the bearings if the sides are not parallel.

    If it was, I would give the BB some break in time.

    As for the spacer, a 70mm shell indicates you have an Italian threaded frame. Check the instructions to see if you need the spacer but my guess is no.
     
  3. oldbobcat

    oldbobcat Well-Known Member

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    Sounds like just the tightness of the seals and the new grease. This will free up with use.

    Make sure the end-nut on the left-hand crank isn't over-tightened. Follow the manufacturer's recommended torque setting.
     
  4. swampy1970

    swampy1970 Well-Known Member

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    I recall that the FSA cranks that I've installed required very little in the way of torque to fasten the bolts and required thread lock compound.

    Do not over tighten and use loctite where required. This isn't a "do it if you feel like it" thing, it's a "if you don't do this you'll probably break something when sprinting out of the saddle and grind your face off on the floor" thing.

    Happy cycling.
     
  5. MrKook

    MrKook New Member

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    I tightened them down just to the point of no gap. I stopped as soon as the gap was gone. I was afraid to over tighten so I did a bit of research first and tried my best not to. Like I said, I didn't put much torque at all, I stopped tightening as soon as the gap between the crank arm and the bottom bracket was gone pretty much.
     
  6. MrKook

    MrKook New Member

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    My frame was not faced. I am going to ride it out and if it's still not as "spinny" as I want it to be I will take it apart and re-install it.

    My bike is a Cannondale (the one in all my photos). So that would not be Italian yeah? The threads seem to agree with any English threads I've used. But, The middle spacer sleeve of the bottom bracket wouldn't even reach both cups if I included the spacer. So I am not about to use it.
     
  7. VCRCBike

    VCRCBike New Member

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    I've replied to this a little while ago but it didn't show up so I apologize if this is a re-post.

    Cannondale uses an English BB. But it should be 68mm. If it is 70mm, you need to have it faced as it is not even close to being correct.

    Facing a BB shell is the most important part when installing an external BB as the shell is responsible for the proper width (68mm) and that the sides are parallel.

    If one or both of those are wrong, the BB will not last.
     
  8. dhk2

    dhk2 Active Member

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    A crank doesn't normally spin for 30 revs after tweaking it by hand, at least no crank I've had has done that. If the seals are worn out, and the grease is gone or replaced with light oil, the no-load drag could be that low, but a new BB with tight seals and grease will have some drag. If the crank will spin over at least 3-4 times, I'd say you're fine.

    Bet if you measure the drag force (using a spring gauge or weights) needed to turn over a crankarm it's only a couple of oz, or less than a newton. Even with a nt of drag, that only translates to a loss of 1.5 watts at normal cadence. As others have said, the drag should decrease a bit with break in miles.
     
  9. MrKook

    MrKook New Member

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    Thanks a lot for the reassurance. Luckily I have mastered a couple of physics classes so I am not completely lost with your informed speech. Ha. Thanks again.
     
  10. MrKook

    MrKook New Member

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    Ok, good to know. It's more like 69.5mm anyway so I am sure your right. The frame was powder coated (before I got it) which I apparently should have mentioned. There is probably some excess paint in the way. I should really take it apart and have it faced. Thanks again for the input.
     
  11. swampy1970

    swampy1970 Well-Known Member

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    Isn't this a Cycling Equipment forum thread?

    Note to self: Must remember to post about my nuts chaffing after a 4 hour ride in the rain in the womens section.
     
  12. swampy1970

    swampy1970 Well-Known Member

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    Does it say in the installation instructions "tighten down just to the point of no gap?"

    Really? Does it?

    No. It doesn't. RTFM.

    If you're going to spend a bunch of cash on a nice set of cranks, spend $100 on a fairly good torque wrench and fit them properly - as per instructions. I've been working on cars 'n stuff for years and I aint guessing what 20 in/lbs feels like, especially with carbon components. If it says use a carbon assembly paste (like with some seatpins) or threadlocker - use it. It's not really optional...

    ... unless you call having your face drag across asphalt at 20mph the other part of the 'optional' and subsequent automated uninstallation procedure.

    Steve and the other mods - can we have a sticky in the cycling equipment forum please, politely asking people to read the installation instructions prior to posting and if there are still any questions then feel free to post? Maybe have an initial 'group effort' to provide links to various tech sections of websites for Shimano, Campag, FSA etc etc... Most manufacturers provide full pdf installation instructions with pretty pictures...
     
  13. swampy1970

    swampy1970 Well-Known Member

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    So let me get this right... You have a set of expensive vernier calipers to measure precisely to less than 1mm but lack a torque wrench?
     
  14. MrKook

    MrKook New Member

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    Swampy 1970. Can you please lay off a bit? I admit I am an amateur in the forum (in general) and cycling world. So sorry for disrupting your online community. I have built bikes in the past and never crashed due to anything I left out during the build process, or at all for that matter. I will take your valid input into consideration (minus the heavy sarcasm and harshness).
     
  15. Dr_hush1417

    Dr_hush1417 New Member

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    Just don't post if you lack the patients to deal with it. Let others "waste their time"

    As for me I'm just a noob also but I installed one of these hollowtech II BBs and got the same thing, just has a little resistance. I was told it's normal, could still be an issue though. *shrugs*
     
  16. MrKook

    MrKook New Member

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    So, I had the frame faced today and I am waiting on a torque wrench and some threadlock to arrive to install every bolt correctly. I also got some carbon installation compound from eBay for my carbon components. I guess swampy's harsh comments made me realize that they're right. If I am going to building something I am going to ride for a 1500+ mile trip, I need to make sure it is done right.
     
  17. Born2bWild

    Born2bWild Member

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    Swampy: Yes, this is the Cycling Equipment forum where people can ask any questions relating to cycling equipment. As you've probably noticed the site has been going under a major overhaul the past month and we're constantly updating. We're in the process of creating a "Workbench" section dedicated to mechanical discussions but for now this is the most relevant section.

    You also have a great point about the install instructions. I'm working directly with major brands to contribute their expertise to the site in the form of our insiders program and adding best practices to our wiki pages.

    Good call on the torque wrench suggestion. Nobody wants to eat pavement while screamin down a hill you just worked your ass off to get up. However, please try and phrase your input in a way that's not abusive to other members. We're all here for the love of cycling and come from all different levels of riding experience.

    If you have any other feedback message me directly.
     
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