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Experienced Mechanic - Rookie Mistake - How?

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Experienced Mechanic - Rookie Mistake - How?

Old 10-17-12, 07:27 AM
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Phil_gretz
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Experienced Mechanic - Rookie Mistake - How?

I'm embarrassed to admit this. Two nights ago I began re-assembly of a stripped down frame. It was late and it'd been a long day and I was tired. Got the headset repacked and adjusted. Then sat down to re-install the cone/loose bearing/spindle bottom bracket assembly. New bearings, grease. You know where this is going...

Without much thought (any thought?) I began with the fixed cup ON THE NON DRIVE SIDE. Darn, the threads must be fouled. Cleaned it, wiped it, regreased it. Ahh, now it's catching, but it's VERY HARD TO TURN - well I cross threaded it in and got to work on the bearings, spindle and other side. Not realizing, I began to cross thread the adjustable side - and thought - this shouldn't be so hard. Maybe I need to have the threads chased.

Took the frame to my friendly, competent LBS, and they just stared at me. YOU PUT THE FIXED CUP ON THE WRONG SIDE! Humiliating. I've done dozens of these. How did I do that? Shame.

Ever done something similarly goofy, when you should've known better?
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Old 10-17-12, 07:50 AM
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Are you sure you didn't use one of the odd Shimano cartridge bottom brackets that are reversed? They were popular in the '90s. The fixed side was installed on the NON-drive side and the adjustable side was installed on the drive side.

I have seen a fair amount of Trek mountain bikes come through our coop with those reversed Shimano bottom brackets. Freaks everyone out until they realize that they are designed like that.

Edit: re-read your posting and noticed you mentioned loose balls, well then I don't know what to tell you. Hopefully the LBS can chase and fix your BB threads.
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Old 10-17-12, 08:14 AM
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I tried to pull a square-taper crank without taking the bolt out once. Fortunately the puller had only engaged a few turns of the thread due to the presence of said bolt, so I was still able to remove the crank after tearing out all the thread that the puller was engaging...

It was more embarassing because I did it at the co-op, although it was my own bike.
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Old 10-17-12, 08:15 AM
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Was alcohol involved?
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Old 10-17-12, 08:23 AM
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Join the club. We have jerseys.

I've done exactly the same thing. I think it's a perception issue.
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Old 10-17-12, 08:28 AM
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I came across this gem awhile ago.....




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Old 10-17-12, 08:34 AM
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Excuses

Originally Posted by dsbrantjr View Post
Was alcohol involved?
Unfortunately, No.

My only explanation is general fatigue, a nagging sense that I had to make progress on this build, and foggy thinking...

The LBS was able to chase the threads, and I installed the BB last night with no issues.

I would have expected someone to say that they had installed brifters (initially) on the wrong sides of the handlebar or something. Imaging telling the customer that this new type of shifting is very much like how a sea lion riding an STI circus bike would shift...
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Old 10-17-12, 08:59 AM
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Originally Posted by Phil_gretz View Post

Ever done something similarly goofy, when you should've known better?
With a BB, my favorite boo-boo is installing the BB, putting the crank back on and realizing the cups aren't quite tight enough. Then trying to loosen the compression ring and tighten with the crank arm on. Sometimes easy to do. Sometimes a PITA.
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Old 10-17-12, 09:19 AM
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A couple of points- First, in this day of only English threading on BBs this reversing is NOT GOOD but BITD with French threadings you could reverse the cups with out harm. Except the lack of access to the adjustible cup now behind the RH arm... Second, is the Bb shell steel or Alu? If Alu the chance of thread damage is greater but the effort of chasing out less. Either way Locktite might be your friend. Third, the cups, when steel, are usually a harder grade of steel. This makes the shell the sacraficial lamb. While, as a hobby frame builder, i would not want to have BB shell's made of hardened steels (that would wear my costly cutters far more quickly), having the new cartridge BB units made of a soft steel might shift the damage to the BB. Of course the Bbs with Alu as their outsides are already pretty soft compared to steel shells. Andy.
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Old 10-17-12, 09:40 AM
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This is an example of what Scuba divers call tunnel vision. You run into a problem, but are so highly focused that you continue making the same mistakes rather than considering alternate solutions. A typical example would be a diver who gets snagged on a fishing line, and works so hard to free himself, that he's soon thoroughly entangled.

I see this often in bike mechanics, who try to bull their way through a problem rather than stopping to see what may actually be wrong. We're all prone to this kind of error, so you have to train yourself to stop and think when you first find a problem. Everything you do working on a bike has a certain pattern, when you find yourself dealing with something that doesn't conform, stop immediately, and go no further until you know what's wrong. Often it helps to simply walk away for a while.
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Old 10-17-12, 09:48 AM
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How much force does it take to thread the cup in the whole way ?
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Old 10-17-12, 10:03 AM
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Carefully marked a fork steerer for cutting, forgetting to include the stem in the stack. Went on and cut it too short.
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Old 10-17-12, 10:20 AM
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Originally Posted by FBinNY View Post
This is an example of what Scuba divers call tunnel vision. You run into a problem, but are so highly focused that you continue making the same mistakes rather than considering alternate solutions. A typical example would be a diver who gets snagged on a fishing line, and works so hard to free himself, that he's soon thoroughly entangled.

I see this often in bike mechanics, who try to bull their way through a problem rather than stopping to see what may actually be wrong. We're all prone to this kind of error, so you have to train yourself to stop and think when you first find a problem. Everything you do working on a bike has a certain pattern, when you find yourself dealing with something that doesn't conform, stop immediately, and go no further until you know what's wrong. Often it helps to simply walk away for a while.
FB... + 1 to that! In fact, in another thread here (Miyata - 'metric') I succumbed to tunnel vision and posted a reply without thinking it all the way through, and you corrected me in a manner which was thoroughly deserved!

The best thing to do if one gets frustrated is to walk away for a bit; take a walk around the block, check your e-mail, watch a funny video on YT. By the time you come back things will look much clearer!

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Old 10-17-12, 10:23 AM
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Originally Posted by FBinNY View Post
Often it helps to simply walk away for a while.
Yep, this is very sound advise. Btw, I once decided to replace the worn rear tire on my MTB. I removed the wheel, pulled the tire off, inserted a new tube, and put it all back together. Everything was fine, until I noticed my brand new, and yet to be installed, rear tire sitting against my garage wall...
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Old 10-17-12, 10:33 AM
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Originally Posted by dsbrantjr View Post
Was alcohol involved?
Originally Posted by Phil_gretz View Post
Unfortunately, No.
Well, there's your problem!

I think we have all had to be bailed out by the LBS once or twice.
It happens.
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Old 10-17-12, 12:18 PM
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Guano happens.
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Old 10-18-12, 05:48 AM
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Originally Posted by DieselDan View Post

Bikes use
brakes to stop.

If your bike has breaks, don't ride it.
Best. Sig. Ever.
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Old 10-18-12, 06:24 AM
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Originally Posted by jolly_ross View Post
Carefully marked a fork steerer for cutting, forgetting to include the stem in the stack. Went on and cut it too short.
I like to assemble it first, then mark for cutting. It's a little more work, but probably worth it.
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Old 10-18-12, 06:49 AM
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Originally Posted by leob1 View Post

i think we have all had to be bailed out by the lbs once or twice.
Never !!!
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Old 10-18-12, 07:43 AM
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Bought a set of built-up wheels. Checked for true and dish. Rear dish was off by a few mm. I've built up a few wheelsets before so I thought correcting the dish would be easy. Over-tightened the drive side spokes, I should have loosened the other side also. After ~2 stripped nipples or so I gave up and took them to the LBS.
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