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oops! I might of over-tightened my crank!

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oops! I might of over-tightened my crank!

Old 03-27-13, 01:13 AM
  #1  
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oops! I might of over-tightened my crank!

So I was putting a crankset on my bike, it is a square taper.
I was tightening the bolt on the drive side because they were shaking whenever I moved them.
I might of tightened it a little bit too much because now when I go to rotate the arms it comes out rough at a certain point.


ps. Sorry for how I explained this.
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Old 03-27-13, 01:34 AM
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I'm also not a big guy in terms of arm strength, so I'm just wondering is it also that easy to over tighten by hand?
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Old 03-27-13, 02:40 AM
  #3  
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Originally Posted by AlexTheRabbit View Post
So I was putting a crankset on my bike, it is a square taper.
I was tightening the bolt on the drive side because they were shaking whenever I moved them.
I might of tightened it a little bit too much because now when I go to rotate the arms it comes out rough at a certain point.


ps. Sorry for how I explained this.
If while rotating the crank, the inside surface of the base of the crank arm is making contact with any part of the bottom bracket other than the square axle, or any part of the crank arm is making contact with the frame's bottom bracket shell, the crank is indeed installed too far into the axle. If the crank was shaking before, there's a good chance the square hole was damaged or enlarged. When the square hole is enlarged, the crank can travel further inward than it should when you're tightening the bolt even if you're only using the correct amount of force. There's no way to correct this situation outside of installing a different crank arm that has an undamaged square hole.

Last edited by vredstein; 03-27-13 at 02:57 AM.
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Old 03-27-13, 03:24 AM
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I should also add that it's almost impossible to overtighten a square taper crank in a single go - the bolt will break before you damage the crank. If you periodically re-tighten them that's different, but whatever's wrong, you haven't overtightened the crank.
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Old 03-27-13, 04:35 AM
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Check if your crank arm is touching any part of the bottom bracket (other than the axle) or bottom bracket shell. If it is not then you need to either overhaul, inspect, and/or replace if you have a cup and cone type BB or replace if you have a cartridge type BB.

-j
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Old 03-27-13, 05:59 AM
  #6  
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You might have overtightened, but as mentioned, that should not cause rubbing. Normally the crank is far enough away from anything to rub. Take a close look as you slowly spin the crank. Perhaps the BB bearings are tight or worn out, and you only just noticed ?
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Old 03-27-13, 07:22 AM
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Originally Posted by Greenfieldja View Post
Check if your crank arm is touching any part of the bottom bracket (other than the axle) or bottom bracket shell. If it is not then you need to either overhaul, inspect, and/or replace if you have a cup and cone type BB or replace if you have a cartridge type BB.

-j
The OP does mention that he "was tightening the bolt on the drive side because they were shaking whenever [he] moved them" which suggests to me that the arm was loose on the spindle. If he has ridden the bike in that condition, it is possible, even likely, that the square taper on the arm has been damaged and enlarged, allowing the arm to seat further on the spindle. A picture of the inside of the square taper on the arm might show this.
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Old 03-27-13, 08:37 AM
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Start out by removing the BB and inspect it.
Remove it and look, do not assume its good because it fills OK!
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Old 03-27-13, 09:51 AM
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I'm guessing that once he removed the play in the crank arm, the rough bottom bracket was more noticeable and had previously been in that condition.
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Old 03-27-13, 10:41 AM
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Originally Posted by vredstein View Post
If while rotating the crank, the inside surface of the base of the crank arm is making contact with any part of the bottom bracket other than the square axle, or any part of the crank arm is making contact with the frame's bottom bracket shell, the crank is indeed installed too far into the axle. If the crank was shaking before, there's a good chance the square hole was damaged or enlarged. When the square hole is enlarged, the crank can travel further inward than it should when you're tightening the bolt even if you're only using the correct amount of force. There's no way to correct this situation outside of installing a different crank arm that has an undamaged square hole.
In the first picture I rotated the crank to the position where it just stays in place, where I can feel a noticeable amount of resistance, this is the only part where I rotate it that there is ANY kind of resistance.
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Old 03-27-13, 10:42 AM
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ps. I'm not too worried about replacing the crank and what not.
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Old 03-27-13, 11:13 AM
  #12  
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Okay, several things. First of all, there are 2 crankarms, one with the chainrings and the other with just the arm. When you are saying, you spin the crank, you are spinning the whole crank and when it gets to one spot, the resistance gets significant.

Now, as to what you did in the original post. You said you tightened down the bolt. There are 2 bolts or nuts that hold the crankarms to the spindle. The spindle is the axle thing that goes in the middle of the bike through the bottom bracket shell that connects the 2 crankarms. What you said was that you think you over tightened the bolt on the drive side because "they" (not sure exactly what you mean by they) were shaking. I am assuming that what you mean is that the drive side crankarm was loose on the spindle and had play in it however the non-drive side arm did not have any play in the crank arm. So you went and tightened down the bolt that holds the drive side crankarm to the spindle.

If that bolt was loose to begin with, not a good thing. When you tighten down that bolt, you need to use a LOT of torque on it. You NEVER want those bolts loosening up or falling out, if they loosen up , they will damage the crank arm on the square taper. You really can't cause any binding by over tightening those bolts since they aren't bearing loaded bolts. I think was happened was that you didn't notice the binding in the crank assembly until after you tightened down the crankarm bolt but remember, tightening down the crankarm bolt really has nothing whatsoever to do with the bearing tightness/binding of a square taper bottom bracket.

So back to square one. You fixed the original problem of the loose crankarm by tightening down the crankarm bolts, good. However I bet you might not have tightened it down enough, for some reason, people have a tendency to be afraid to tighten down those bolts.

Now you have to figure out what is wrong with the bearings in the bottom bracket. Do you know if you have a loose ball/spindle bottom bracket or a cartridge bottom bracket?
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Old 03-27-13, 11:19 AM
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I just looked at your pictures again. I just realized something, the bike you have looks to be an old earlier '70s era bike of some sort. I wonder if you used a JIS taper crankarm on a ISO bottom bracket which means it would be possible for the crankarm to come too close to the bottom bracket shell/lock ring. The common JIS square taper is a tad larger than the old school ISO square taper and woudl allow a crankarm to come closer to the bottom bracket shell.

Looking at the pictures, the crankarm does appear to be seated far too deeply on the bottom bracket spindle and that it might be hitting the lockring.

What kind of crankarm was originally on the bike and what kind of bike is it?
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Old 03-27-13, 11:22 AM
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Originally Posted by AlexTheRabbit View Post
In the first picture I rotated the crank to the position where it just stays in place, where I can feel a noticeable amount of resistance, this is the only part where I rotate it that there is ANY kind of resistance.
Looking at your pictures, I can't see any clearance between the arm and the fixed cup, but the angle makes it difficult to judge. It also appears that your fixed cup may not be fully seated in the bottom bracket shell. Is this perhaps an Italian or French frame where there is a propensity for the fixed cup to loosen with riding? It's possible that if your fixed cup can be fully seated the arm will have the clearance it needs to rotate freely.
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Old 03-27-13, 11:22 AM
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It is a peugeot that I picked up for 20 bucks and when I got it the cranks were practically destroyed.
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Old 03-27-13, 11:25 AM
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What brand of cranks were the original? And what kind of crank is the new one?>

Look at this link for more info http://sheldonbrown.com/bbtaper.html

It talks about how european bikes used the ISO bottom bracket spindles which might explain why the new crank is so close the lockring.
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Old 03-27-13, 11:29 AM
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http://bmxmuseum.com/forsale/pict0333_blowup.jpg
sugino vp crank.
uhhh for the crank that I put on it, it is some local brand called "state bicycle co" I decided to check them out since they were not too bad of a price.
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Old 03-27-13, 11:38 AM
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Originally Posted by AlexTheRabbit View Post
http://bmxmuseum.com/forsale/pict0333_blowup.jpg
sugino vp crank.
uhhh for the crank that I put on it, it is some local brand called "state bicycle co" I decided to check them out since they were not too bad of a price.
If you loosen the crankarm bolt holding the crankarm to the spindle, can you just pull the crankarm off or will you need a puller? Can you take a picture of the old crankarm mounted onto the bottom bracket spindle? I'm still wondering if we have a JIS crank mounted on an ISO spindle issue.

Is the bike setup as a single speed? I only see one chainring on the Sugino crank.
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Old 03-27-13, 11:41 AM
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I need to remove it with a puller, originally when I was first removing the first crankarm it just fell off.
I'll probably PM you that picture because I'm not in the mood to remove it at the moment
Yeah it is being set up as a single speed.
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Old 03-27-13, 11:47 AM
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Originally Posted by AlexTheRabbit View Post
I need to remove it with a puller, originally when I was first removing the first crankarm it just fell off.
I'll probably PM you that picture because I'm not in the mood to remove it at the moment
Yeah it is being set up as a single speed.
You don't have enough posts to use PM at this time, I think you need 50+ posts to use it.

I would also like to see some pictures of the bolt mounting point when you remove the bolt BEFORE you remove the crankarm or put the puller in place. I just wonder if your picture will look like this one which is an indication of a too small taper bottom bracket used with a modern JIS crankarm:

(photo courtesy of Sheldon Brown's website)
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Old 03-27-13, 11:54 AM
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Originally Posted by bobotech View Post
You don't have enough posts to use PM at this time, I think you need 50+ posts to use it.

I would also like to see some pictures of the bolt mounting point when you remove the bolt BEFORE you remove the crankarm or put the puller in place. I just wonder if your picture will look like this one which is an indication of a too small taper bottom bracket used with a modern JIS crankarm:

(photo courtesy of Sheldon Brown's website)
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Old 03-27-13, 11:58 AM
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Originally Posted by AlexTheRabbit View Post
Not looking good.... That looks like the fitting bolt has almost bottomed out against the end of the spindle.
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Old 03-27-13, 12:03 PM
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Originally Posted by AlexTheRabbit View Post
Bingo, that is exactly what I was worried about. The bottom bracket is an old style ISO with a thinner taper that bottoms out on a modern JIS spindle. The crankarm has sunk too deep onto the spindle.

You will need to replace the bottom bracket spindle with a modern JIS taper spindle and you will probbaly be fine. I bet that even the original SUgino crankarm could still be used. If you keep trying to use the original bottom bracket spindle, you will keep running into this issue of crarnkarms working themselves loose and causing more damage.
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Old 03-27-13, 12:05 PM
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Your crankarm should end up with a nice little gap between the spindle and the bolt mounting surface, something like this:


(courtesy Sheldon Brown again)
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Old 03-27-13, 12:06 PM
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Originally Posted by bobotech View Post
Bingo, that is exactly what I was worried about. The bottom bracket is an old style ISO with a thinner taper that bottoms out on a modern JIS spindle. The crankarm has sunk too deep onto the spindle.

You will need to replace the bottom bracket spindle with a modern JIS taper spindle and you will probbaly be fine. I bet that even the original SUgino crankarm could still be used. If you keep trying to use the original bottom bracket spindle, you will keep running into this issue of crarnkarms working themselves loose and causing more damage.
So how much would that cost me about?
So it would be possible to use the old crankset?
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