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Old 03-12-11, 08:53 PM   #1
sillygolem
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Keeping one piece cranks together

Is there a way to permanently keep the left side cone on a one piece crank from loosening? I've found on the bikes that have these I have to re-tighten the cone and lock ring every couple months.
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Old 03-12-11, 10:54 PM   #2
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Is there a way to permanently keep the left side cone on a one piece crank from loosening? I've found on the bikes that have these I have to re-tighten the cone and lock ring every couple months.
Loctite. You'll have to completely degrease the threads on the crank,cone and lockring in order for the Loctite to bond properly. Be careful when tightening the lock ring because the metal on both the crank and ring can be rather soft and strips easily.
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Old 03-13-11, 12:22 AM   #3
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Originally Posted by sillygolem View Post
Is there a way to permanently keep the left side cone on a one piece crank from loosening? I've found on the bikes that have these I have to re-tighten the cone and lock ring every couple months.
You should determine the real problem first. The cone and locknut should remain fixed together and the adjustment not change for much longer than a "couple months". It could be that the fixed cone (on the chainring side) is moving, or the threads are damaged, or the cups are collapsing inward due to wear. Any of these require disassembly to verify.
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Old 03-13-11, 08:32 PM   #4
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Is there a washer between the locknut and adjustable cone? If it's missing, proper adjustment/tightening can be difficult.
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Old 03-13-11, 08:42 PM   #5
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The possibly missing washer is the key to your problem. These cranks worked fine for decades without adhesives, so if yours keeps loosening, it might be that either you forgot the washer, are using one whose key on it is sheered off. The system depends on keying the washer to the crankshaft so the cone and locknut cannot rotate together.
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Old 03-14-11, 09:48 AM   #6
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What kind of bike are we talking about? Older department store bikes used Wald bottom brackets and many newer bikes use cheap Chinese steel bottom brackets. Both of these are made from soft metal which wears quickly and they rarely stay adjusted. You might want to check the cones for wear and see if either of the press-in cups are cracked or broken.
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Old 03-15-11, 01:08 AM   #7
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I have three bikes right now from different eras ('71 3-speed, mid-70's 10-speed, and a modern BSO) that I've had this problem with. None of them have any cone wear, although I'm wondering if I don't have a little grease on the threads from the bearings.
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