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Old 01-21-03, 08:55 AM   #1
Barnaby
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BB and Threading

I have an old steal racer that has a BB with 2 adjustable cups and two lock rings. In other words it does not have the traditional fixed cup and adjustable cup, both sided thread in to where you want the chainline to be, and then you tighten up both lock rings.
The BB shell is Italian Threading, so that the drive side has a right-hand thread. Sheldon Brown and others have identified this as being a poor engineering idea since right-hand threading has a tendency to unthread under force-which has happened to me about five times.
The BB is a sealed cartridge and the cups sleeve over it on both ends.
My idea is to put the BB on my other touring bike that has English thread, and:
1- Get either adustable cups for left and right again, the idea being that the drive side would be left-threaded and not be prone to undoing, or;
2-Get an adjustable and fixed cup to sleeve over the cartridge in English threading.
Will either of these solutions work or be worth it?
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Old 01-21-03, 09:13 AM   #2
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Originally posted by Barnaby
I have an old steal racer that has a BB with 2 adjustable cups and two lock rings. In other words it does not have the traditional fixed cup and adjustable cup, both sided thread in to where you want the chainline to be, and then you tighten up both lock rings.
The BB shell is Italian Threading, so that the drive side has a right-hand thread. Sheldon Brown and others have identified this as being a poor engineering idea since right-hand threading has a tendency to unthread under force-which has happened to me about five times.
The BB is a sealed cartridge and the cups sleeve over it on both ends.
My idea is to put the BB on my other touring bike that has English thread, and:
1- Get either adustable cups for left and right again, the idea being that the drive side would be left-threaded and not be prone to undoing, or;
2-Get an adjustable and fixed cup to sleeve over the cartridge in English threading.
Will either of these solutions work or be worth it?
There is nothing wrong with Italian threading. Unthreading is a non issue if tightened extra tight. Non permanent loctite is an option,but I've never had to resort to it. Your best bet for using that BB on your english thread bike is to get the proper threaded replacement cups if they are available.
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Old 01-21-03, 12:59 PM   #3
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Depending on what cranks you are using, you might do better getting a new bb. Bottom brackets are relatively cheap.

As far as Italian threaded, the RH/RH configuration may be theoretically less desirable than the RH/LH English threading. However, in a properly maintained and locked bb, where is the torque on the cups when pedalling? The spindle is rotating freely in lubricated ball bearings is it not? Perhaps if the bearings are allowed to get rusty and frozen, torque could be transmitted to the cup, but is that an engineering issue? Or perhaps failure to use appropriate pin spanner and lockring tool or proper technique could leave the lockup inadequate. My old Bianchi is Italian threaded, and I have complete faith in the bb installation (traditional cup and cone fixed/adjustable early '80s Shimano 105 bb).
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Old 01-21-03, 01:31 PM   #4
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Originally posted by RainmanP
Depending on what cranks you are using, you might do better getting a new bb. Bottom brackets are relatively cheap.

As far as Italian threaded, the RH/RH configuration may be theoretically less desirable than the RH/LH English threading. However, in a properly maintained and locked bb, where is the torque on the cups when pedalling? The spindle is rotating freely in lubricated ball bearings is it not? Perhaps if the bearings are allowed to get rusty and frozen, torque could be transmitted to the cup, but is that an engineering issue? Or perhaps failure to use appropriate pin spanner and lockring tool or proper technique could leave the lockup inadequate. My old Bianchi is Italian threaded, and I have complete faith in the bb installation (traditional cup and cone fixed/adjustable early '80s Shimano 105 bb).
They really do tend to loosen on the drive side even if everything is right.It's counter intuitive.You just may have gotten them tight enough.
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Old 01-21-03, 03:16 PM   #5
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Counter-intuitive is right! Is that why English threads tighten rearward? What causes the loosening then? BB shell flex?
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Old 01-21-03, 03:52 PM   #6
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Originally posted by RainmanP
Counter-intuitive is right! Is that why English threads tighten rearward? What causes the loosening then? BB shell flex?
When you are pedaling forwrd,it's intuitive to think the bearings in the BB are spinning the same way.Not the case,and that's the counterintuitive part.Think sheldon has something on it.Italian threading and loosening tendency is also more a reason for BB shell facing to insue full contact at the BB flange/shell interface.But it isn't critical,as I dont' do it and just make sure the shell face is free of paint and BB is extra tight.
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Old 01-21-03, 09:13 PM   #7
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Although a Loctite-treated, heavily torqued Italian or French-threaded fixed cup will generally hold together (two of my five bikes fall into this category), RH thread on the drive side is a fundamental engineering mistake, for the same reason that a RH-threaded left pedal would be. The bearings exert an epicyclic (counter-rotating, counter-intuitive) force against the bearing cup. Putting adjustable cups on both sides is indeed an interesting way to accommodate chainline tuning.

Incidentally, one of my friends attempted to build a crossover drive tandem crankset from three conventional Sugino cranksets, only to discover that the two RH-threaded pedals on the left side and the LH-threaded pedal on the captain's right indeed tended to self-loosen with use. He eventually cross-threaded LH-threaded pedals on the left and a RH-threaded pedal on the captain's right.

By the way, last year I was surprised to observe that one of Jimmy Thompson's 24 Hetchins classics came from the factory with a backward English-threaded BB, with the (LH-threaded) fixed cup on the LEFT side!
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Old 01-21-03, 11:12 PM   #8
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My old Bianchi is Italian threaded, and I have complete faith in the bb installation (traditional cup and cone fixed/adjustable early '80s Shimano 105 bb).
There may be a difference here in that in your situation,the fixed cup with flange is on the drive side where the torque may be greater and the spindle end longer . My understanding is that the fixed side in cup and cone systems is usually fully tightened and then left alone, with the flange firmly against the BB shell,while servicing is done from the left side. My two-sided adjustable cup system with two lock rings seems to me to trade off this resulting stiffness for adjustability in chainline.

Quote:
The bearings exert an epicyclic (counter-rotating, counter-intuitive) force against the bearing cup. Putting adjustable cups on both sides is indeed an interesting way to accommodate chainline tuning.
If this is the case with the counter-rotating effect, it seems to me that the unthreading on the right with Italian right threading would be solved with the same cartridge in my other bike which has the English left-threaded BB shell on the drive side, or am I as dumb as I look?

As far as tighening I had been used to tightening my cup and cone system to remove as much play as I could without binding. With this system, I only use the pin wrench on both cups to move the BB to where I want the chainline, and then tighten like hell the lock rings on both sides. It seems that these very light alloy rings are expected to handle quite a lot of stress on maybe three threads per side.I have only used loctite once on the rings only, and have started greasing the underside of the cups where they come into contact with the cylinder since a bed-squeeking sound seems to eminate from there as evidenced by etching or scoring marks on the cylinder walls.
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Old 01-21-03, 11:20 PM   #9
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Originally posted by Barnaby


There may be a difference here in that in your situation,the fixed cup with flange is on the drive side where the torque may be greater and the spindle end longer . My understanding is that the fixed side in cup and cone systems is usually fully tightened and then left alone, with the flange firmly against the BB shell,while servicing is done from the left side. My two-sided adjustable cup system with two lock rings seems to me to trade off this resulting stiffness for adjustability in chainline.



If this is the case with the counter-rotating effect, it seems to me that the unthreading on the right with Italian right threading would be solved with the same cartridge in my other bike which has the English left-threaded BB shell on the drive side, or am I as dumb as I look?

As far as tighening I had been used to tightening my cup and cone system to remove as much play as I could without binding. With this system, I only use the pin wrench on both cups to move the BB to where I want the chainline, and then tighten like hell the lock rings on both sides. It seems that these very light alloy rings are expected to handle quite a lot of stress on maybe three threads per side.I have only used loctite once on the rings only, and have started greasing the underside of the cups where they come into contact with the cylinder since a bed-squeeking sound seems to eminate from there as evidenced by etching or scoring marks on the cylinder walls.
The fixed cup on the drive side will still loosen if not tightened properly. same will happen even with a shimano or campy cartridge type. You probably need to ditch that Edco and get a campy or shimano unit.you shouldn't have a problem with the english thread cups in the other frame.
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