silverclaws
Senior Retro Guru
For something to do, I tried out my new Shimano type bottom bracket removal tool, and removed the cartridge style bearing, a BB-LP30, which was useful, as it gave an indication to the age of my atb, that being 1993 or 94. Anyway having got this thing out after finding how stiff and notchy it was without the cranks attached I discovered something. Now, my understanding of the term 'sealed bottom bracket' meant that crud can't get in there and maybe water too, but the grease will guard against water. I pulled out the seals to take a look only to find the bearing interspaced with grit, that grit I assume is mud and dust, stuff that has got in there.
So, I have come to the conclusion so called sealed bottom brackets are not the best option for longevity, in that the fit and forget mentality can make people unaware of what exactly is happening down there, a case of, 'oh, it's sealed, it will be ok', as they plough through muddy water, I have done it myself. But that seal that is in there, it is only a rubber lip, it being lubricated by the grease that is on it, grease being what it is, it attracts and holds filth, which dries out the grease and starts the destruction, the seals failing, grit and water gets into the precious bearings.
So the thought is all this fancy complex and expensive transmission we have on these bikes, it is pretty useless if the bottom bracket is failing, the thing we can't see, and perhaps don't think about, but it is probably it is one of the most important parts of the drive system.
Now my bottom bracket has no play in it, but it is grindy graunchy and stiff indicating to me the bearings have a problem or the start of a problem, and I cant get at them. I could I suppose take all the seals off and flush it through then pump in new grease, fit the seals back if they are not too badly damaged, but methinks there is a better option, go back to the old way of doing it, with the screw in cup and bearings that ride between the axle and cups, that way, come maintenance time the whole lot can be stripped out, cleaned and inspected, any problems can be sorted before they become big problems.
Adjusting bearings is a skill, but the old system the bearings could be adjusted to take up the slack of wear and the lockring can be released and tightened with the multi tool method, the screwdriver and hammer if the right tools are'nt available. Perhaps by old ideas, a hole can be drilled in the lowest point of the BB to allow water to drain out, water that gets past the very same type of rubber seals.
But back to the 'sealed' cartridge type bottom bracket, surely it's reason for existence is to aid cycle manufacture, just simply bung it in, no skills required, in fact all these cartridge type assemblies are designed for ease, but what a waste.
I have just got to find out now where I can get an old type assembly, hopefully something lighter than the 320 g lump of steel I took out of my bottom bracket, can anyone shine a light on where I might get such a thing ?
So, I have come to the conclusion so called sealed bottom brackets are not the best option for longevity, in that the fit and forget mentality can make people unaware of what exactly is happening down there, a case of, 'oh, it's sealed, it will be ok', as they plough through muddy water, I have done it myself. But that seal that is in there, it is only a rubber lip, it being lubricated by the grease that is on it, grease being what it is, it attracts and holds filth, which dries out the grease and starts the destruction, the seals failing, grit and water gets into the precious bearings.
So the thought is all this fancy complex and expensive transmission we have on these bikes, it is pretty useless if the bottom bracket is failing, the thing we can't see, and perhaps don't think about, but it is probably it is one of the most important parts of the drive system.
Now my bottom bracket has no play in it, but it is grindy graunchy and stiff indicating to me the bearings have a problem or the start of a problem, and I cant get at them. I could I suppose take all the seals off and flush it through then pump in new grease, fit the seals back if they are not too badly damaged, but methinks there is a better option, go back to the old way of doing it, with the screw in cup and bearings that ride between the axle and cups, that way, come maintenance time the whole lot can be stripped out, cleaned and inspected, any problems can be sorted before they become big problems.
Adjusting bearings is a skill, but the old system the bearings could be adjusted to take up the slack of wear and the lockring can be released and tightened with the multi tool method, the screwdriver and hammer if the right tools are'nt available. Perhaps by old ideas, a hole can be drilled in the lowest point of the BB to allow water to drain out, water that gets past the very same type of rubber seals.
But back to the 'sealed' cartridge type bottom bracket, surely it's reason for existence is to aid cycle manufacture, just simply bung it in, no skills required, in fact all these cartridge type assemblies are designed for ease, but what a waste.
I have just got to find out now where I can get an old type assembly, hopefully something lighter than the 320 g lump of steel I took out of my bottom bracket, can anyone shine a light on where I might get such a thing ?
