Bicycle Mechanics - question for "old timey" mechanics

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une_vitesse
08-13-10, 08:11 AM
i'm having a difficult time keeping my cup and cone bottom bracket bearing assemblies in adjustment. here's my process (we're assuming the bb shell is faced and the bb is in good shape):

- regardless of country of origin, i install the fixed cup with locktite 242 get it pretty tight.
- i almost always install the bb with decent to good quality loose balls (i stock 300 and 25 grade), 11x1/4inch on either side most of the time.
- i insert the spindle and install the adjustable cup and lockring with grease (should i use locktite on these as well? i hope not)
- i make my preload adjustment ( here i'm looking for minimal play and friction with the lockring tight)
-i mark the position of the adjustable cup in relation to the bb shell
- i install my test crank (an old sq taper crank with a one-key release cap) on the drive side and check again for play (the crank acts as a lever amplifying the play in the bearing assembly and the one key release cap allows me to install and remove the crank quickly and easily)
- if there is play, i loosen the lockring and rotate the adj. cup by 1 degree increments and tighten the lockring. i repeat this until the play as been eliminated.
-i take my test crank off, feel the bb (here, depending on the quality of bb, it goes from super smooth to alright)
-install the crankset

i take the ride out for a 10-15min test ride, and when i get back, the bottom bracket almost always has play. what the hell am i doing wrong, please help me!~!!!


une_vitesse
08-13-10, 08:17 AM
after the test ride, if i check the fixed cup (which i admit to not doing all the time), it is always tight. i use the the 36 mm fixed cup wrench held in place with my headset cup press. for french and italian bottom brackets i'll even increase the length of the wrench handle to get more leverage.

rhenning
08-13-10, 08:34 AM
It is normal to readjust the bottom bracket after a few miles as the bearings and other parts seat themselves. Just something you always did. Roger


une_vitesse
08-13-10, 08:41 AM
It is normal to readjust the bottom bracket after a few miles as the bearings and other parts seat themselves. Just something you always did. Roger

that's what i thought, until installed the bb on my nugget and it hasn't developped play. funny thing is i would have expected it to do so, since it's a franken-bb, with campy cups a dura ace spindle.

cny-bikeman
08-13-10, 08:44 AM
Your procedure is far more conscientious than that employed by many bike shops. Assuming you are at least at times overhauling used equipment I would find it unusual to see significant play after everything you did. Certainly one further adjustment should resolve the problem for a long period. The only possible variable you left out was indicating that the bearing tracks are smooth (pit free) and evenly worn.

Normal riding should not loosen up a bottom bracket. By normal riding I mean not tromping on high gears all the time and avoiding the "Roy Rogers" mount/dismount (swinging on or off the bike on one pedal). Yes, I know people get away with doing that, but the crank/bb is not designed for what can be a large amount of stress (depending on rider weight) on one point over and over. If it works for you, fine - but if problems occur it's best not to do.

FBinNY
08-13-10, 08:55 AM
You shouldn't need locktite at all, and you're making the process overly complicated.

You also need to understand that BBs and headsets are different in the adjustment process because of the effects of the lock nut (lock ring). On a headset tightening the locknut pushes the top cup down slightly tightening the bearing. On a BB tightening the lockring pulls the cup out slightly loosening the bearing.

Install the right cup with adequate torque (75ft#s+), Install the left cup and adjust for zero play, plus a bit of preload, tighten the lockring and the load will relax a bit, check your work. I prefer to mount the right crank before adjusting, because I can use it to check play, but again the key is to slightly overtighten the bearing so tightening the lockring brings it back to where you want it.

une_vitesse
08-13-10, 09:07 AM
Your procedure is far more conscientious than that employed by many bike shops. Assuming you are at least at times overhauling used equipment I would find it unusual to see significant play after everything you did. Certainly one further adjustment should resolve the problem for a long period. The only possible variable you left out was indicating that the bearing tracks are smooth (pit free) and evenly worn.

Normal riding should not loosen up a bottom bracket. By normal riding I mean not tromping on high gears all the time and avoiding the "Roy Rogers" mount/dismount (swinging on or off the bike on one pedal). Yes, I know people get away with doing that, but the crank/bb is not designed for what can be a large amount of stress (depending on rider weight) on one point over and over. If it works for you, fine - but if problems occur it's best not to do.

i don't get to do many new cup and cone bb installations, but i do a lot of bb overhauls. now that i think about it, the two new njs builds i did do (new sugino 75 bb) did go really well, did not develop play after test ride (or to my knowledge, since installation) .
thanks for the vote of confidence on my procedure. i admit that i only use it if the races are smooth and if i'm convinced the spindle is straight. i use a ball point pen on the races, and to be honest, i don't have a good way to check the spindle. i just roll it on a flat surface and observe. maybe that's the weak point of my process. but if the spindle is bent, then the bb would never stay in adjustment, right?

FBinNY
08-13-10, 09:19 AM
and if i'm convinced the spindle is straight. i use a ball point pen on the races, and to be honest, i don't have a good way to check the spindle. i just roll it on a flat surface and observe. .... but if the spindle is bent, then the bb would never stay in adjustment, right?

Most spindles are made of one piece including the bearing cone area. As such they're heatreated to high hardness, and have almost zero ability to bend before breaking. I've never seen a bent steel spindle, and it's something you won't ever see either. If it is able to bend, the issue isn't that it won't keep the adjustment, but that the material isn't hard enough and will wear rapidly.

Obviously, pitting will make a bearing rougher, but that's not something you should try to compensate for by loosening. The bearing has to be adjusted for zero play, otherwise the down pressure will drive the spindle down between balls at 5 and 7 oclock, wedging them around and greatly raising ball to ball load. It's far better to have a properly adjusted BB even if it feels rough, than a sloppy one, which is why I prefer using a crank to check play, over fingers to feel for friction.

une_vitesse
08-13-10, 09:19 AM
You shouldn't need locktite at all, and you're making the process overly complicated.

You also need to understand that BBs and headsets are different in the adjustment process because of the effects of the lock nut (lock ring). On a headset tightening the locknut pushes the top cup down slightly tightening the bearing. On a BB tightening the lockring pulls the cup out slightly loosening the bearing.

Install the right cup with adequate torque (75ft#s+), Install the left cup and adjust for zero play, plus a bit of preload, tighten the lockring and the load will relax a bit, check your work. I prefer to mount the right crank before adjusting, because I can use it to check play, but again the key is to slightly overtighten the bearing so tightening the lockring brings it back to where you want it.

c'mon francis, read my procedure. i may be a little verbose (blame years of reading barnett's manuals) , but my procedure's basically the same as yours.
i understand that a bb lockring works differently than a headset or hub locknut, thankyouverymuch. and i know that a crank is a good tool to amplify play in the bb bearing assembly.

FBinNY
08-13-10, 09:33 AM
c'mon francis, read my procedure. i may be a little verbose (blame years of reading barnett's manuals) , but my procedure's basically the same as yours.
i understand that a bb lockring works differently than a headset or hub locknut, thankyouverymuch. and i know that a crank is a good tool to amplify play in the bb bearing assembly.

Sorry I offended you, but you misunderstood.

I didn't say your procedure was wrong in any way, only more complicated than necessary. For example marking the cup in 1° increments, or removing the right crank after installing it to check play.

As for whether you knew or didn't know that tightening the lockring would loosen the adjustment, don't take that personally. I had no way of knowing what you know, and figured that might account for the play found later. Even if I suspected you knew that, I probably would have mentioned it anyway because others read the thread and it might help them.

lverhagen
08-13-10, 09:51 AM
This has been greatly informative. Thank You.

Cheers

wrk101
08-13-10, 10:09 AM
I don't use locktite, I use an antisieze compound on both sides.

I don't use a test crank, I just install the drive side and do my testing with it.

Your procedure should work just fine.

une_vitesse
08-13-10, 10:14 AM
Sorry I offended you, but you misunderstood.

I didn't say your procedure was wrong in any way, only more complicated than necessary. For example marking the cup in 1° increments, or removing the right crank after installing it to check play.

As for whether you knew or didn't know that tightening the lockring would loosen the adjustment, don't take that personally. I had no way of knowing what you know, and figured that might account for the play found later. Even if I suspected you knew that, I probably would have mentioned it anyway because others read the thread and it might help them.

Oh no, i'm not offended at all. i'm just surprised and a little disappointed that you didn't seem to read my original posting thoroughly. Remember, i started this thread to get critique on my procedure. critique that will allow me to not have to do that secondary adjustment that almost always seems necessary after my original one.

une_vitesse
08-13-10, 10:16 AM
by the way, francis, how do you measure the torque spec on the fixed cup. i am not aware of any open 36mm crow's foot.

une_vitesse
08-13-10, 10:20 AM
I don't use locktite, I use an antisieze compound on both sides.

I don't use a test crank, I just install the drive side and do my testing with it.

Your procedure should work just fine.

i only use a test crank to make sure i didn't overshoot my adjustment and end up with a too tight bb (it forces me to remove it and check bb bearing for smoothness)

BCRider
08-13-10, 10:34 AM
Just to echo that the proper amount of preload is the key. ALL bearings must have some measure of preload to avoid the balls every becoming loose as the bearing flexes. If you look around and read about what happens if the preload goes away it's not a pretty thing. The load shifts to one or two balls and the races "click" them around and all the load suddenly pinpoints on one ball instead of being shared by all the balls in the loaded half of the bearing. This is VERY hard on both the balls as well as the races. Other than corrosion too low a preload is very likely the chief cause of brinneling and fracture wear that produces the pitting and rough looking bearing tracks. Now one may think that this is a steel bike but steel is an eleastic material every bit as much as rubber or latex. It just needs special tools to note the amount of flexure under loads. And with a BB using cups and cones the bearing has a lot of material between the two sides to stretch and potentially allow the balls to lose their preload. And the rider is working this bearing pair using a set of levers to enhance their power. So don't begrudge using a little bit of preload that is enough to produce a slight drag in the bearings. With car wheel bearings they are adjusted so that it takes a certain amount of torque to begin moving them. For a BB we don't need to get that crazy but there should be a noticable amout of preload drag in the 3 to 5 inch-oz range that you can easily feel with your fingertips. If it spins easily then it's just too loose. That may well be the reason for your slight play after the first ride. A combination of the parts settling and maybe the initial amount of bearing ball damage. Using some preload before that first ride may well keep things consistent for a lot longer.

davidad
08-13-10, 10:53 AM
http://www.sheldonbrown.com/brandt/bb-adjust.html

une_vitesse
08-13-10, 10:53 AM
okay. that is what i needed to read. even if there is no noticeable play (with crank installed), if the spindle spins easily in my fingers, the preload setting is too low and the bearing assembly's adjustment is too loose.
i need to go back and check how the nugget's bb feels without the cranks. that bike's bb was cobbled together using campy cups and a shimano DA spindle. i installed it, i seem to remember that it spun smoothly without the cranks and had no play with the cranks on. still doesn't have play.

mrrabbit
08-13-10, 10:56 AM
As FBinNY stated, no loctite necessary.

Lock that drive side cup down like a SOB!

With high end BB such as Campy, DA, Superbe, etc., when done locking that lockring down you'll have a slight preload leftover. A spot-on adjustment will turn into slight play by the time you check at the pedal.

Once again, with high end BBs, slight preload should be leftover. Smooth but with a "extra heavy grease" kind of drag...


With el-cheapo BBs, typcially black spindles that require the bearing to clear and shine the race section - you will need considerable preload when done locking the lockring down. I.e., you'll feel the bearings pretty well but easily spin without any "indexing". Furthermore you'll be adjusting about every 6 months cause the spindles and the cups will keep wearing in. Cheap is cheap.

If this is an old MTB that gets mashed...forget it - go sealed cartridge bearing unit. There's a reason why folks with old Suntour / SR equipped GT Tequesta's kept changing over to Phil Wood units and then later competing stuff a year or so later including Shimano.

=8-)

BCRider
08-13-10, 11:19 AM
....that bike's bb was cobbled together using campy cups and a shimano DA spindle. i installed it, i seem to remember that it spun smoothly without the cranks and had no play with the cranks on. still doesn't have play.

The issue is that while it feels good in the stand it's not under load in the stand. If it helps to understand this it's much like a poorly tensioned wheel. If someone that doesn't understand the dynamics of a spoked wheel is holding a low tensioned wheel in their hand. To them it feels just fine with the spokes all quite tight and "twang'y" :D. Yet we know that inadequite tension will result in the spokes on the lower side going too loose and failing. But our wheel newbie would hold the wheel up and think "WTH, they are all still tight. What went wrong?". What went wrong is that they didn't take into account the wheel is composed of a lot of elastic elements and that as the load is put on that system it will react by very slightly altering the centering of the hub to the rim and that the rim will very slightly alter it's shape. The spokes don't stretch much as we know but it's enough to see the spoke tensions alter radically as the wheel comes under load and that slight movement is enough to lower the tension of the spokes on the bottom of the wheel. And as we know too low a tension in this case allowed the lower spokes to "take a break"... literally as well as figuratively.

Bearing shell flexing under load that causes the bearing ball preload to go away and allow the cup and cone to move out of concentricity will work the balls in a manner very analagous to that poorly tensioned wheel.

We see another example of this in setting the bearings on a QR wheel. You've likely already done these adjustments where you either clamp the QR skewer in the axle for the adjustment or play with getting just the right amount of play so that when the skewer is clamped it just goes away. The skewer in this case is compressing the axle that last thou or two that closes and preloads the wheel bearings. This is the most obvious example of what I mean when I say that steel is actually elastic. It also shows why we need preload in each bearing to allow for this elastic movement of the metal to occur without going so far that the balls lose full contact in any of the bearings.

fietsbob
08-13-10, 12:06 PM
There are 2 Campag type cups , one has grooves in the inside to, while rotating, expel grit
without a direct contact with the crankarm, It the cup, is thicker ,
needs a spindle with the bearings slightly closer in together .

there is a Bicycle research tool that clamps onto the fixed cup wrench
using the axle end,
to keep wrench on the cup facets, and so get it sufficiently tight,
so as to not come loose.

Anti seize and grease will reduce likelihood of the rust bonding parts together over time.
and help you get the fixed cup torqued down adequately.