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  1. #1
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    Crank Fell Off....Possible Noob Question

    My Shimano Hones that I installed myself were working great (around 50 miles or so) up until recently. With only split second warning, the left crank just fell off. I don't know if it's my fault or Shimano's, but I'm leaning toward the former. Here is the evidence...

    I used that little plastic thing (Tool Tl-FC16, whatever that means to you) to tighten the other little plastic cap on the crank. I hand tightened it pretty hard.

    Then the left crank just fell off, and the cap disappeared. What do I do?

    I know this is very badly written and vague (...little plastic thing...What do I do?...) but I'm a new technology noob and I tried my best. Any help is greatly appreciated.

    Thanks in advance!
    TIMM
    I wish I didn't know now what I didn't know then.

  2. #2
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    After more investigation, I see that a strip of the splines on the crank where it attaches to the BB seem prematurely worn as do the splines on the BB.

    Hope that helps you answer my horrible noobish question!
    TIMM
    I wish I didn't know now what I didn't know then.

  3. #3
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    Did you also tighten the pinch-bolts on the left crank?

  4. #4
    Vaginatarian
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    sounds like you didnt have it fastened properly , and as it worked itself off it damaged the splines, if you can get it back on, retighten the bearing pre load (the plastic thingy), then tighten & torque the pinch bolts and use blue loctite on the pinch bolts, grease on the splines

  5. #5
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    Quote Originally Posted by dan0
    sounds like you didnt have it fastened properly , and as it worked itself off it damaged the splines, if you can get it back on, retighten the bearing pre load (the plastic thingy), then tighten & torque the pinch bolts and use blue loctite on the pinch bolts, grease on the splines
    I got the crank back on with little trouble, and I did tighten the pinch bolts pretty tight-if to the correct torque I don't know. Why should I use grease on the splines; did you mean to get them on?

    I wish they made the Hone's in silver; the paint wears too fast.

    Thanks for the reply & advice! You saved me from cumbersome emails!
    TIMM
    I wish I didn't know now what I didn't know then.

  6. #6
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    could i ask what bb shell width you have and what amount of bb spacers you have used,as my bud had this same problem,or it could be down to the little plastic spacer between the pinch bolt halfs.

  7. #7
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    Quote Originally Posted by tibug
    I got the crank back on with little trouble, and I did tighten the pinch bolts pretty tight-if to the correct torque I don't know. Why should I use grease on the splines; did you mean to get them on?

    I wish they made the Hone's in silver; the paint wears too fast.

    Thanks for the reply & advice! You saved me from cumbersome emails!
    TIMM
    grease on the splines help a little when getting it on , but more importantlyy to get it off later, same with seatposts and pedals. when you have 2 different metals they tend to weld together unless seperated by a thin layer of grease or anti sieze. and when torqueing the fittings together it helps them seat.

  8. #8
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    You can order a Dura-Ace or XTR aluminum compression cap to replace the plastic one. Tighten that one first, and then the pinch bolts.

    I don't have the plastic spacer for my Saints. They've never loosened up on me. So whatever.

  9. #9
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    The splines on the axle have no reason to wear under normal use. If they are damaged, it's because the crank wasn't attached correctly. The plastic "spacer" is not a spacer. You'll notice that it has a small metal 'key' protruding from it half-way along its length. This 'key' will drop, or can be pushed, into a corresponding indent on the axle when the crank is pressed on the correct distance. It also acts as one of three compressions which hold the crank in place. The pinch bolts should be tightened a little at a time, alternating bolts so that they have more or less equal torque. If you don't have the Shimano instructions, go get them from the Shimano website.
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  10. #10
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    Quote Originally Posted by konut
    could i ask what bb shell width you have and what amount of bb spacers you have used,as my bud had this same problem,or it could be down to the little plastic spacer between the pinch bolt halfs.
    I have a 63mm shell, and 2 spacers on the drive side; 1 on the non drive.

    Thanks!
    TIMM
    I wish I didn't know now what I didn't know then.

  11. #11
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    Quote Originally Posted by tibug

    I wish they made the Hone's in silver; the paint wears too fast.
    They do make them in silver. They're called LX.

  12. #12
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    Quote Originally Posted by robdamanii
    They do make them in silver. They're called LX.
    Ahhhh! That's why they weigh the same!

    OT: Where can I get the LX's cheap? I might start a new build within this lifetime...

    Thanks!
    Tim
    I wish I didn't know now what I didn't know then.

  13. #13
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    Quote Originally Posted by tibug
    I have a 63mm shell, and 2 spacers on the drive side; 1 on the non drive.

    Thanks!
    TIMM
    dunno what to suggest as i just fitted saints and i am having no problems,the only thing i have noticed between the saints and my buds hone was,where the crank arm pinch bolts are on the hone there seems to be a little plastic spacer inbetween the crank pinch bolt halfs,where as on the saint there is none,if you have the little plastic spacer try and remove that.

    sorry is that 68mm shell also,and are you running a chain guide.

  14. #14
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    Quote Originally Posted by konut
    dunno what to suggest as i just fitted saints and i am having no problems,the only thing i have noticed between the saints and my buds hone was,where the crank arm pinch bolts are on the hone there seems to be a little plastic spacer inbetween the crank pinch bolt halfs,where as on the saint there is none,if you have the little plastic spacer try and remove that.

    sorry is that 68mm shell also,and are you running a chain guide.
    I'm not running a chain guide. So, if I tighten the pinch bolts right, then the crank shoudn't move? I just can't see what I did wrong...

    Yea, I won't remove that spacer; I'll probably just screw it up more.

    Thanks!
    TIMM


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  15. #15
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    Where did you purchase? It is possible that it was defective. I had a similar problem with an FSA crank that I had replaced under warranty where the threads stripped off.

    Just another possibility besides user error.

  16. #16
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    Quote Originally Posted by tron
    Where did you purchase? It is possible that it was defective. I had a similar problem with an FSA crank that I had replaced under warranty where the threads stripped off.

    Just another possibility besides user error.
    I bought it at Jenson and waited 3 months for it to ship . Interesting that you had the same problem; do you know what was wrong with the cranks? Is there anything visible I should look for? I'll check Shimano's warranty policy.

    MUCHOS Gracias!
    TIMM
    I wish I didn't know now what I didn't know then.

  17. #17
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    I'm sorry to say that it sounds like an installation-related issue. The arm will not just fall off if it is properly installed. For example, that plastic cap is nearly impossible to remove when the pinch bolts are properly torqued.

    Without seeing exactly how you installed the cranks, I don't know where it went wrong, but I suspect it had something to do with how you torqued the pinch bolts. Out of curiosity, what distance does the spindle stick out from the bearing before you install the crank arm?

    The method ot attaching the left crank arm is very good. The basic principle has been used for a long time on bicycle cranks (Red Line Flight II cranks from the early 80s).

    I would suggest having someone who is familiar with crank installation to help you out on your next set.
    May the air be filled with tires!

  18. #18
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    If you look at the specialized page under the roadbikereview board there were many people with problems using an FSA crank like this. But that was FSA. Its really hard to say what the cause of your problem is without knowing exactly how you installed the cranks.
    I think with the Shimano cranks that you have, no threads would have been stripped and you could just re-install? or maybe take it to the shop for a second opinion.

  19. #19
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    Thanks for all your help! I reinstalled the crank and tightened the pinch bolts down like my life depended on it, or at least as hard as I could go without the allen wrench tearing through my hand. Stop, I know what you're thinking. Torque wrench, right? Wish I had one. Anyway, I hope it holds, and if it don't then I should be able to simply replace the left crank arm because as of now, the splines on the bb aren't to screwed up.

    Blaster: You just got to blame it on me don't you? JK, thanks for your honest diagnosis and advice. The spindle is out far enough; the threads are completed revealed, of course assuming that the crank arm stays on!

    I think it was a simple mistake of just not tightening the pinch bolts to the correct torque, as Blaster and others have mentioned. I am not one of the best mechanics you'll find, but I consider myself proficient enough to install these easily installed cranks. Ah well, I guess anyone can make my mistake. I just wish I didn't...

    Thanks again all!
    TIMM
    I wish I didn't know now what I didn't know then.

  20. #20
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    tibug,
    Mistakes happen. Fortunately you didn't get hurt.
    Ya know, I have to give you credit. Many of my friends who admit that they aren't mechanically inclined won't even attempt to work on their bikes. Heck, even some I know claim to know how to do stuff often find a lame excuse why they won't actually do it.

    So good job of giving it an attempt.
    May the air be filled with tires!

  21. #21
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    Blaster: Thanks for the positive reply! Yea, I didn't get hurt, and it was an absolute miracle that it fell off literally 100 ft from my house!

    One last noobish question. Do I really need that bearing adjustment cap. How exactly does it adjust the bearings?

    Thanks!
    TIMM
    I wish I didn't know now what I didn't know then.

  22. #22
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    Yes, you need the cap. Well...sort of.
    I'm not sure if you've seen the tool used to install the cap, but you don't use any tools with it. The amount of effot to tighten the cap is all that is needed for proper bearing preload.

    The bearings don't have a collar or spacer between the inner race. As you tighten the cap, it squeezes the bearings between the crankarms. If you were to somehow overtighten the cap, the bearings would have an excessive load on them. The cranks would turn slowly, and the bearings would fail prematurely.

    If you simply install the crank arm without the cap, you wouldn't put any load on the bearings. Although you wouldn't likely be able to feel it, there may be a slight bit of side-to-side movement in the cranks.

    Until you order a cap (they're very cheap, BTW), do this: Install the arm as far as you can. Get a long bolt (you may be able to make a quick release skewer to work) with large washers on either end. Insert the bolt throught the crank spindle to effectively sandwich the cranks together between the washers and the bolt (make sense?). Sorry, I'm kind of lazy right now to think about a better way of writing it. Then tighten a nut on the bolt finger tight. Now tighten the pinch bolts, alternating between the two. You don't need to use your gorilla muscles. Moderately tight is fine. You don't want to strip the threads in the crank arm.
    May the air be filled with tires!

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