SKF vs. NTN - fully sealed bearings

Discuss light weight issues concerning road bikes & parts.
TheKaiser
Posts: 496
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

Note, combined 2 different Hambini posts here, as I didn't see a multiquote option:
hambini wrote:
Tue Feb 20, 2018 7:40 pm
As the balls rotate inside the bearing they are causing a fluctuation in air pressure and hydraulic pressure. When the pressures get too much the seal will deflect away from the inner race for them to equalize.

NSK is about the same as FAG and SKF.

This whole industry is a bit incestuous as a lot of them share production lines. Hambini
That is interesting about the pressures and seals. I don't expect you to give me a whole physics lession here on the forum, but is there anywhere you can suggest that I might learn more about this phenomenon? Like some bearing company's whitepaper, or a mechanical engineering journal or something? I can imagine that as a bearing heats, or due to a venturi effect, then you could get positive pressure in the bearing, which would lift the seal lip, but it seems that would be finite and would stop once the bearing reached equilibrium with the surrounding environment, which would return it to it normal (higher) amount of drag. It also seems like it would result in a vac in the bearing once it returned to a static state, which could end up sucking in water if it were present at the seal lip at that time, or if the seals were sufficient to hold the vac then it means that the seal lift effect would diminish with repeated use. Splitting hairs here, I know, but geeking out on this stuff can be fun.

Regarding the incestuous nature of the bearing industry, I have often been struck by the fact that, in order to be in the business, it seems to be a requirement to have a 3 letter acronym as your name. Maybe there is a reason for this, like easy printing on tiny products or something, but it is striking, and holds true even across many international borders.

pdlpsher1
Posts: 1541
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

TheKaiser wrote:
Wed Feb 21, 2018 3:02 am
Regarding the incestuous nature of the bearing industry, I have often been struck by the fact that, in order to be in the business, it seems to be a requirement to have a 3 letter acronym as your name. Maybe there is a reason for this, like easy printing on tiny products or something, but it is striking, and holds true even across many international borders.
You need a total of three engineers to design a bearing. One for the races, one for the balls, and another for the seals :D

mattr
Posts: 3502
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

hambini wrote:
Tue Feb 20, 2018 7:40 pm
This whole industry is a bit incestuous as a lot of them share production lines.
It's worse than that. We had a supply issue with on of our suppliers a few years ago. They flagged it up early, change to raw material supplier, delays in productions etc etc.
"Whats your solution"

"We'll send bearings from a factory you haven't approved, we'll have to do more inspections"

Turns out that their non approved factory was actually the one they were using to manufacture their "competitors" bearings as a subcontractor.. So we got about a months worth of bearings with the wrong manufacturers markings on them. Absolutely identical in every other way.

hambini
Posts: 131
Joined: Tue Nov 15, 2016 8:13 am

by hambini

TheKaiser wrote:
Wed Feb 21, 2018 3:02 am

That is interesting about the pressures and seals. I don't expect you to give me a whole physics lession here on the forum, but is there anywhere you can suggest that I might learn more about this phenomenon? Like some bearing company's whitepaper, or a mechanical engineering journal or something? I can imagine that as a bearing heats, or due to a venturi effect, then you could get positive pressure in the bearing, which would lift the seal lip, but it seems that would be finite and would stop once the bearing reached equilibrium with the surrounding environment, which would return it to it normal (higher) amount of drag. It also seems like it would result in a vac in the bearing once it returned to a static state, which could end up sucking in water if it were present at the seal lip at that time, or if the seals were sufficient to hold the vac then it means that the seal lift effect would diminish with repeated use. Splitting hairs here, I know, but geeking out on this stuff can be fun.

Regarding the incestuous nature of the bearing industry, I have often been struck by the fact that, in order to be in the business, it seems to be a requirement to have a 3 letter acronym as your name. Maybe there is a reason for this, like easy printing on tiny products or something, but it is striking, and holds true even across many international borders.
The ASME tribology journal is worth a read. They went through the pressure business in quite some detail in one of their issues from a few years ago. Recently there was an article from Schaeffler about the development of the campag CULT bearings. I am unsure if you have to pay to subscribe - I automatically get it sent through as a "perk" of my day job.

My background is not in tribology but I have been to many conferences and there is a huge market out there for the design of seals on bearings.

HTH Hambini

PLuKE
Posts: 202
Joined: Sat Aug 16, 2014 5:26 pm
Location: Suffolk, UK

by PLuKE

So, if I am to replace my Zipp bearings, which is the best way to go in terms of seals?

I want the fastest bearing, I am crap in the hills, so tend to chug up them slowly, so if some seals have more drag at a lower RPM, then that’s isn’t ideal for me? Most of my riding is fairly flat/rolling.

Durability isn’t to much of an issue, as I don’t ride in any wet weather or do mega miles anymore.

Would the LLU be best for me?

Luke

pdlpsher1
Posts: 1541
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

PLuKE wrote:
Wed Feb 21, 2018 4:08 pm
So, if I am to replace my Zipp bearings, which is the best way to go in terms of seals?

I want the fastest bearing, I am crap in the hills, so tend to chug up them slowly, so if some seals have more drag at a lower RPM, then that’s isn’t ideal for me? Most of my riding is fairly flat/rolling.

Durability isn’t to much of an issue, as I don’t ride in any wet weather or do mega miles anymore.

Would the LLU be best for me?

Luke
I've asked the same question earlier and the answer I got is that I should remove the seals for the lowest friction. And I have reasons to brelieve that the NTN bearings are so good that running them without seals is just fine. Take a look at the attached video. TheDarkInstall is a WW member here.


PLuKE
Posts: 202
Joined: Sat Aug 16, 2014 5:26 pm
Location: Suffolk, UK

by PLuKE

pdlpsher1 wrote:
Wed Feb 21, 2018 5:23 pm
PLuKE wrote:
Wed Feb 21, 2018 4:08 pm
So, if I am to replace my Zipp bearings, which is the best way to go in terms of seals?

I want the fastest bearing, I am crap in the hills, so tend to chug up them slowly, so if some seals have more drag at a lower RPM, then that’s isn’t ideal for me? Most of my riding is fairly flat/rolling.

Durability isn’t to much of an issue, as I don’t ride in any wet weather or do mega miles anymore.

Would the LLU be best for me?

Luke
I've asked the same question earlier and the answer I got is that I should remove the seals for the lowest friction. And I have reasons to brelieve that the NTN bearings are so good that running them without seals is just fine. Take a look at the attached video. TheDarkInstall is a WW member here.

Thanks

I don’t think I would run them without a seal, no wet riding, but if I was caught in a shower, or any fine sand particles etc.

Will take a look at the video.....

Luke

pdlpsher1
Posts: 1541
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

In the video TheDarkInstall illustrated that he got zero bearing wear on a NTN bearing without seals for 60,000kms.

hambini
Posts: 131
Joined: Tue Nov 15, 2016 8:13 am

by hambini

If you want the fastest no drag and are prepared to oil frequently. Then do as the Dark INstall did and oil the bearings and run without seals.

If you want a bit of protection then LLB is a solid choice.

Hambini

PLuKE
Posts: 202
Joined: Sat Aug 16, 2014 5:26 pm
Location: Suffolk, UK

by PLuKE

pdlpsher1 wrote:
Wed Feb 21, 2018 7:59 pm
In the video TheDarkInstall illustrated that he got zero bearing wear on a NTN bearing without seals for 60,000kms.
Interesting video. I am not sure I would run them without seals personally. Maybe the front wheel, but he rear wheel maybe not, due to the freehub and the dirty that gets attracted to this area.

I keep my bike and running gear clean, but even still.

Thanks
Luke

PLuKE
Posts: 202
Joined: Sat Aug 16, 2014 5:26 pm
Location: Suffolk, UK

by PLuKE

hambini wrote:
Thu Feb 22, 2018 5:43 pm
If you want the fastest no drag and are prepared to oil frequently. Then do as the Dark INstall did and oil the bearings and run without seals.

If you want a bit of protection then LLB is a solid choice.

Hambini
I want the fastest, but I guess there’s a slight compromise. Would removing the seals every few hundred miles damage the seals?

I will take a look at the LLB.

Thanks for replying!

Luke


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