# Loose ball bearings - What 'grade' are the stainless shamans?



## StillKeen (Oct 4, 2005)

I have moved on from the cheap $1 bag of low grade bearings I used to buy from the LBS, and have bought some 'grade 10' thru hardened ball bearings for my xtr and dura-ace wheels.

I have read shimano use grade 25 (which are less round/variable to what I have), but they just state 'stainless steel' in the exploded diagrams.

I am worried my non-stainless and hardened ones will be too hard, and rather than the 'soft' stainless steel wearing, it will damage the races.

Does anyone know what the spec is for shimano's top bearings? Looking for something like ANSI 123192 grade 25 or similar ... 

Thanks


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## Kerry Irons (Feb 25, 2002)

*Stick with what you have*



StillKeen said:


> I have moved on from the cheap $1 bag of low grade bearings I used to buy from the LBS, and have bought some 'grade 10' thru hardened ball bearings for my xtr and dura-ace wheels.
> 
> I have read shimano use grade 25 (which are less round/variable to what I have), but they just state 'stainless steel' in the exploded diagrams.
> 
> ...


I think your best bet is to use the grade 10 bearings. The cups and cones are hardened steel and I doubt the harder bearings will be an issue, and that assumes that indeed they are any harder than the OEM bearings.


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## TomH (Oct 6, 2008)

Im curious where you got G10 steel bearings. I could never find better than G25 (all though G25 is probably overkill in itself) without going to ceramics, in loose ball.

When i was looking into bearings before, every source i found said dura-ace/xtr used G25.


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## StillKeen (Oct 4, 2005)

TomH said:


> Im curious where you got G10 steel bearings. I could never find better than G25 (all though G25 is probably overkill in itself) without going to ceramics, in loose ball.
> 
> When i was looking into bearings before, every source i found said dura-ace/xtr used G25.


This is where I purchased them from.
Loose Ball Bearings Stainless and Steel Chrome - Buy Online Simply Bearings Ltd

If we take a look at the difference between the AISI52100 and 316, the hardness (HRC I guess is Hardness Rockwell 'C'?) is much harder. The 52100 is proper hardened steel, like you'd make press tools or injection mould tools from (I think from memory P-20 steel is in the 60s), but the 316 are right down at 25 - 39 ... that is significantly softer.

I had heard Campag use trade 25, but they also sort them into closer matched sets, so effectively tighter. (actually, maybe it was shimano use 25 and campag 100 and sort ... can't remember).

I just don't know if 316 in grade 10 or 25 exist.

Grade 10 - AISI 52100 Chrome Steel
Ball Diameter: 4.76mm = 3/16 inch
Material: AISI 52100 Chrome Steel 
Min Crush Load: 1370kg 
Hardness: *60-67* HRC 
Hardness Depth: Through Hardened 
Corrosion Resistance: Keep Oiled 

Grade 100 (not sold in grade 25 or 10 anywhere I can find yet).
Ball Diameter: 4.76mm = 3/16 inch

Material: 316 Stainless Steel 
Min Crush Load: 1370kg 
Hardness: *25-39* HRC 
Hardness Depth: Through Hardened 
Corrosion Resistance: Excellent


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## StillKeen (Oct 4, 2005)

Found this, so looks like the 420 stainless ball bearings do come in higher (lower number) grades ... but which do Shimano use, 420 (hard ... not as hard as the non-stainless ones I've got, but close) or the soft 316?


A martensitic stainless steel offering good strength, hardness and wear resistance combined with moderate corrosion resistance.
It is magnetic.
Material Composition	
Carbon (C) < 0.15% to 0.4%
Chrome (Cr) 12.0% to 14.0%
Silicon (Si) < 1.0%
Manganese < 2.0%
Posphorous (P) < 0.045%
Sulphur (S) < 0.03%
...
Hardness: 50 to 56 HRC
...
Corrosion Resistance	
Provides a good combination of corrosion resistance with hardness. Although not quite as good as 440C it provides a good alternative in most situations
...
Available Grades	
AFBMA Grade: 10, 20, 25, 28, 50, 100, 200, 500, 1000, 2000
*ISO Grades: 10, 20, 25, 28*, 50, 100, 200, 500, 1000, 2000
DIN 5401: Class I, Class III, Class IV, Class V
Applications	
Ball Bearings, Valves, Ball Screws,
...


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## StillKeen (Oct 4, 2005)

StillKeen said:


> ....
> Applications
> Ball Bearings, Valves, Ball Screws,
> ...


Oh, that was the other thing ... ''ball bearings, valves and ball screws'' ... does 'ball bearings' mean any ball bearing application like a bike hub?


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## DavidsonDuke (Sep 12, 2006)

Dura Ace hubs are known for lasting forever, being smooth, and rock solid construction and reliability. Why would one need to "upgrade" the kind of bearings used? Or am I missing something?


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## StillKeen (Oct 4, 2005)

Two things really, 1) I can buy shimano bearings for £8 for a rear hub, and they should be the same as the hub came with. So that is an option. 2) I should be able to buy the exact same thing in moderate bulk from a bearing supplier for less. It's not like Shimano/Campag make the bearings. This would allow a cost savings. So not a big deal on one hub, but I have five bikes and about that many sets of shimano hubs, so if I can get them in bulk for £2/wheel, I can replace them all each year.

Shimano operate a business, and maybe the next grade up in bearings would work better, but it's not worth it for them to fit. My hope is that using the same material bearings Shimano use, but a higher grade, will allow the cup and cones set closer without having to leave enough of a gap to accommodate the least round bearing.

Right now I've spent £20 on enough grade 10 bearings to do 10 hubs, but want to make sure I'm not fitting 65 rockwell hardness bearings into races that are designed for 35 rockwell.


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## TomH (Oct 6, 2008)

The bearing tolerance is so tiny that you wouldnt be able to adjust the cones any closer. The bearing variation on G25 is 0.000025 inch, grade 10 is 0.000010 inch, so at best you could set the cones .000015 inch closer.

From what I can tell, im using ~HRC 60 chrome steel bearings in my shimano hubs. After a season the cones look as they should, no wear.


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## giosblue (Aug 2, 2009)

I got some stainless bearing from Simply Bearing, they're only a couple of mile up the the road.

The ones I got were AISI 316 Grage 100

are these any good?. I haven't used them yet


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## TomH (Oct 6, 2008)

Those are fairly low quality bearings. vxb.com has grade 25's for dirt cheap. I got a huge bag of them for something like 10 bucks. For the price of bearings, I wouldnt bother buying anything less than G25. They do run a little smoother than G100, but not hugely.


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## Kerry Irons (Feb 25, 2002)

*Understanding ball bearings*



TomH said:


> Im curious where you got G10 steel bearings. I could never find better than G25 (all though G25 is probably overkill in itself) without going to ceramics, in loose ball.
> 
> The bearing tolerance is so tiny that you wouldnt be able to adjust the cones any closer. The bearing variation on G25 is 0.000025 inch, grade 10 is 0.000010 inch, so at best you could set the cones .000015 inch closer.
> 
> When i was looking into bearings before, every source i found said dura-ace/xtr used G25.


G10 bearings are readily available, though sometimes you have to buy large quantities at a time.

You don't use better bearings so you can adjust the hubs more closely. Better bearings mean longer lasting bearings, cups, and cones. Think of the cup and cone arrangement as a rigid, circular tube (open on the sides) through which the bearings must pass with each revolution of the hub. If the bearings are not uniform in size or the cups and cones are not precisely machined, then some of the bearings will be "loose" in the tube while others will be tight and the "tube diameter" will vary as the bearings roll around the hub. 

The tight fit spots will force some of the bearings to bear more of the load and this will accelerate wear.

Historically, Campy has hand selected bearing lots to get the equivalent of Grade 1 bearings, which cannot be purchased commercially. This is one of many reasons for the extreme durability and very smooth rolling nature of Campy componenets.


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## giosblue (Aug 2, 2009)

TomH said:


> Those are fairly low quality bearings. vxb.com has grade 25's for dirt cheap. I got a huge bag of them for something like 10 bucks. For the price of bearings, I wouldnt bother buying anything less than G25. They do run a little smoother than G100, but not hugely.



Are they better than the steel ones you get from your local LBS?

Next time I'll look for some grade 25s

I've just had another look at simply bearings website. I can't find any better grade than 100.

Just had another look at my bearings, the 3/16 are AISI 316 and the 1/4 are AISI 420.
It looks like I got the wrong ones in 3/16, I should have got AISI 420. Apparently the AISI 420 is a harder bearing. I suppose they will be ok for the front wheel.


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## Dumb Founder (Dec 21, 2021)

Campy hand selecting every single individual bearing for each hub? I call b.s. in this. Even if they did this, it's impossible to manufacture a steel bearing to that kind of tolerance, hand picked or not.


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## No Time Toulouse (Sep 7, 2016)

Dumb Founder said:


> Campy hand selecting every single individual bearing for each hub? I call b.s. in this. Even if they did this, it's impossible to manufacture a steel bearing to that kind of tolerance, hand picked or not.


Well, maybe 11 years ago (when this thread was posted...) it might've been true. Hand-sort to get all those in a tighter tolerance for roundness, and those that don't get sent for use in 'lesser' machines. AS for how tight a tolerance is possible; I'm sure the Japanese can do it.


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## Kerry Irons (Feb 25, 2002)

Dumb Founder said:


> Campy hand selecting every single individual bearing for each hub? I call b.s. in this. Even if they did this, it's impossible to manufacture a steel bearing to that kind of tolerance, hand picked or not.


Do you not understand the difference between choosing a bearing lot (for which specific data are available on nominal diameter and variability) and hand selecting each individual bearing? Campy was able to select bearing lots such that they were more similar to what they had purchased in the past than if they just bought bearings of that specification. Before spouting off about something, you should have at least a basic understanding of industrial practices.


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## No Time Toulouse (Sep 7, 2016)

Yes, a "matched lot" is nothing unusual. Top engine builders often request a "matched set" of connecting rods and pistons, not because anything else is worthless, but in order to have a set of parts which are all NEARLY the same dimension (which, in the case of the engine, makes them better-balanced). Choosing a matched set of bearings means that forces are more even than in an unmatched set, which means that you are less likely to have a bearing failure.


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