Suggestion on keeping crank from coming loose?
07-13-18, 11:01 AM
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Suggestion on keeping crank from coming loose?
I was having issues with chain rub on the front derailleur. I thought something could be bent, but I didn't consider the crank could be coming loose. On last nights ride it came all the way off. I put it back on and tapped it with a mallet, but after a couple of pedal strokes, it slides out just a bit and starts a chain rub or worse a gear change to the smaller ring.
I'm afraid I damaged it somehow not realizing the problem. Any suggestion on keeping it tight and flush?
I'm afraid I damaged it somehow not realizing the problem. Any suggestion on keeping it tight and flush?
07-13-18, 11:11 AM
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Is there a bolt involved in holding that crank on? If not, it is broken and can't be fixed. Replace it.
07-13-18, 11:47 AM
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The bottom bracket in the photo looks like an Octalink and there certainly should be a clamp bolt keeping the crank in place if that's the correct bottom bracket. I don't know what's plugging them center of the crank you are holding but something is seriously broken or wrong and that crank doesn't match the pictured bottom bracket.
07-13-18, 11:58 AM
#4
Bicyclerider4life
Unfortunately, the crank looks stripped to me, where it goes onto the bottom bracket.
The bottom bracket looks fine though.
I'd say it is time for a new crank and crank bolts.
The bottom bracket looks fine though.
I'd say it is time for a new crank and crank bolts.
07-13-18, 12:49 PM
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Thanks for the feedback, was hoping for a prayer. If curious, this is the other side of the crank. Just presses on, no bolt Seems an odd choice for a cross bike.
07-13-18, 12:53 PM
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That crank appears to two piece Hollowtech II type, and there is no bolt. We are seeing a permanent press fit spindle with no bolt that has broken out of the crank. The hole in the crank is blind.
07-13-18, 12:55 PM
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It's broken.
07-13-18, 01:32 PM
#9
Banned
never had a problem with my square taper drivetrain (BB/ Cranks) other than I changed things over time..
Cross has ceased to mean much these days just another category .
.. hybrid with drop bars..
If less than a year old the bike shop may warrantee it..
but may not if you raced cyclocross much..
may be a Loc Tite Product you can use to essentially Glue it back on.
....
Cross has ceased to mean much these days just another category .
.. hybrid with drop bars..
If less than a year old the bike shop may warrantee it..
but may not if you raced cyclocross much..
may be a Loc Tite Product you can use to essentially Glue it back on.
....
Last edited by fietsbob; 07-13-18 at 01:37 PM.
07-13-18, 02:37 PM
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never had a problem with my square taper drivetrain (BB/ Cranks) other than I changed things over time..
Cross has ceased to mean much these days just another category .
.. hybrid with drop bars..
If less than a year old the bike shop may warrantee it..
but may not if you raced cyclocross much..
may be a Loc Tite Product you can use to essentially Glue it back on.
Cross has ceased to mean much these days just another category .
.. hybrid with drop bars..
If less than a year old the bike shop may warrantee it..
but may not if you raced cyclocross much..
may be a Loc Tite Product you can use to essentially Glue it back on.
Gluing or Loctiting the OP's crank back together is a preposterous idea and will only succeed in getting someone hurt. Hopefully no one takes such advice seriously.
07-13-18, 03:20 PM
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Trying to glue an arm, another bad idea. I wouldnt even trust a good weld in such a place. Replace the arm. Even had it not been inferior cast. Its a good time to upgrade the whole crank.
Last edited by meerzistar; 07-13-18 at 03:25 PM.
07-13-18, 04:33 PM
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I don't see what's stupid about the design. FSA has made cranks this way for many years. This is the first one that came apart I've heard of.
07-13-18, 04:41 PM
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The crank and bottom bracket in the OP's photo are not compatible with each other and the photo is misleading. And, yes, the crank has had the pressed-in spindle snap off and is now a throw-away.
07-13-18, 04:43 PM
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07-13-18, 04:52 PM
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This is the weirdest thread. Does no one else understand what we're looking at? That's a BB86, the pressed in version of an external BB but for 19mm spindles 2 piece cranks. The exposed spindle is not part of the bb, it is what's broken out of the two piece crank - you would normally never see those splines.
07-13-18, 04:52 PM
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That is really embarrassing. It's exactly the fear 99% of people had when they first came out with this design, that Shimano would neglect to press the drive side crankarn to the spindle tight enough. "Are you sure it's attached, PERMANENTLY?"
And sure enough, they finally succeeded. Gotta be careful when you outsource. Would be interesting to know which country it came from.
And sure enough, they finally succeeded. Gotta be careful when you outsource. Would be interesting to know which country it came from.
Last edited by Colnago Mixte; 07-13-18 at 05:12 PM.
07-13-18, 05:25 PM
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This is the weirdest thread. Does no one else understand what we're looking at? That's a BB86, the pressed in version of an external BB but for 19mm spindles 2 piece cranks. The exposed spindle is not part of the bb, it is what's broken out of the two piece crank - you would normally never see those splines.
07-13-18, 05:34 PM
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It's just like a Hollowtech crank, but the permanently attached spindle has separated from crankarm. None of the two piece cranks are truly two piece - all of them use a steel or aluminum spindle pressed into an aluminum arm.
07-13-18, 05:35 PM
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07-13-18, 05:56 PM
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07-14-18, 07:33 AM
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Yes, I certainly understand how HTII and similar cranks are made, I just found the photo difficult to interpret. As you noted, the grooves for the spindle aren't obvious.
07-14-18, 01:14 PM
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07-14-18, 08:32 PM
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I'll plead ignorance. I'm kind of hard on bikes weather those press on cranks have a good track record or not I wouldn't feel piece of mind with them under my feet. Knowing it is possible they can come apart.
07-15-18, 12:27 AM
#25
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there are some very high strength adhesives made .. aerospace, rocket science..
but I a am not going to find them for you or teach you surface prep for them
so lazy fix is ... buy a new chainset..
.....
but I a am not going to find them for you or teach you surface prep for them
so lazy fix is ... buy a new chainset..
.....
Last edited by fietsbob; 07-15-18 at 11:20 AM.