chriswoody
Legendary Member
- Location
- Northern Germany
So modern bikes increasingly make more use of sealed cartridge bearings rather than loose bearings in a cup and cone arrangements, however, they are still disposable items and need replacing from time to time. I'm lucky in that both my Gravel and Mountain bike only have sealed bearings in the wheels and headsets, but looking into how to replace the freehub bearings on the gravel bike without investing in hundreds of Euros of tools has led me down a deep rabbit hole.
So the diagram below shows a modern front and rear hub, in the rear hub four different sealed bearings can be seen, two in the hub itself and two in the freehub, the two I'll need to extract soon. Separating these bearings a small tube can be seen, this is the preload tube and sets the exact distance between the sets of bearings and hence preload. The sealed bearings themselves are an interference fit into the shell of the hub or freehub body.
Now a quick Google for bearing extraction hacks will quickly find many suggestions to gently push this preload tube to the side and tap the back of the bearing with a screwdriver or punch, working evenly around the diameter of the bearing to remove it as straight as possible. Problems with this method are the potential to slip and damage the actual hub shell itself or not apply enough even pressure on the bearing and again potentially damage the shell as the bearing comes out at an angle. Another issue is that not all preload tubes actually move to one side and hence deny access to the reverse side of the bearing.
So another way to do this is to buy a blind bearing pulling kit and rather than spend hundreds of Euros on a bike specific one, there are cheaper €50 ones on Amazon that are recommended by a few folk as being more than adequate for the average home bike mechanic. I was quite keen on this approach until I read this article on Hambini's website:
https://www.hambini.com/bearing-extraction-using-blind-bearing-pullers/
This article makes a very valid point that the collet on the puller will damage the preload tube as it expands behind the bearing. This will take the form of flaring on the end of the preload tube and hence shorten it, which it turn negatively affects the preload.
There are suggestions in the above article about recommended tools for the extraction of bearings, but they are eye wateringly expensive and out of the reach of the home mechanic.
One other possible solution is this tool from Wheels Manufacturing and this is an expanding collet that grips the inner race and then gets punched through from the other side.
At €40 it's a lot cheaper than the dedicated tools, but will it work? I can see a couple of potential pitfalls, but maybe I might try. So what do folks think? am I overthinking this? are there other methods I've not thought of and what methods do others use? or is life too short and just take it to a bike shop?
So the diagram below shows a modern front and rear hub, in the rear hub four different sealed bearings can be seen, two in the hub itself and two in the freehub, the two I'll need to extract soon. Separating these bearings a small tube can be seen, this is the preload tube and sets the exact distance between the sets of bearings and hence preload. The sealed bearings themselves are an interference fit into the shell of the hub or freehub body.
Now a quick Google for bearing extraction hacks will quickly find many suggestions to gently push this preload tube to the side and tap the back of the bearing with a screwdriver or punch, working evenly around the diameter of the bearing to remove it as straight as possible. Problems with this method are the potential to slip and damage the actual hub shell itself or not apply enough even pressure on the bearing and again potentially damage the shell as the bearing comes out at an angle. Another issue is that not all preload tubes actually move to one side and hence deny access to the reverse side of the bearing.
So another way to do this is to buy a blind bearing pulling kit and rather than spend hundreds of Euros on a bike specific one, there are cheaper €50 ones on Amazon that are recommended by a few folk as being more than adequate for the average home bike mechanic. I was quite keen on this approach until I read this article on Hambini's website:
https://www.hambini.com/bearing-extraction-using-blind-bearing-pullers/
This article makes a very valid point that the collet on the puller will damage the preload tube as it expands behind the bearing. This will take the form of flaring on the end of the preload tube and hence shorten it, which it turn negatively affects the preload.
There are suggestions in the above article about recommended tools for the extraction of bearings, but they are eye wateringly expensive and out of the reach of the home mechanic.
One other possible solution is this tool from Wheels Manufacturing and this is an expanding collet that grips the inner race and then gets punched through from the other side.
At €40 it's a lot cheaper than the dedicated tools, but will it work? I can see a couple of potential pitfalls, but maybe I might try. So what do folks think? am I overthinking this? are there other methods I've not thought of and what methods do others use? or is life too short and just take it to a bike shop?
