SKF vs. NTN - fully sealed bearings

[vinuneuro]

NTN seals also do not "lift" until you hit around 40-60RPM (depends on the size). Below that speed they are designed to statically seal whereas most others are not.

HTH

Hambini

What does this mean?

Thanks in advance

[hambini]

Thanks for the good info Hambini. If I had known about this earlier I would have removed one seal per bearing before I installed the bearings. This would have saved me half of the total seal drag. I have watched one bearing video by Oz Cycling (link provided in thread) and he found that seal drag is minuscule compared to drag from the grease. I guess I could also do the experiment myself by removing the seals on a new NTN bearing however I’m afraid of damaging the seals. I hope the seals will break-in somewhat after more miles. I also have a set of Campy Boras that don’t use sealed bearings. And those wheels spin forever compared to my other set that uses sealed bearings.


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If you are spinning the wheels in free air without riding them you will always find full seals stop quicker. As the speed of the wheel drops the seal friction increases and the last low speed bit is where it stops quickly. On a completely unsealed bearing you will find the last slow speed bit takes ages to stop. OZ cycling dipped his bearings in petrol to ditch the grease and then spun them around on his fingers and proclaimed the lubricant was the biggest cause of friction. This isn't really a good test because the bearing is unloaded - no preload and no radial load

NTN seals also do not "lift" until you hit around 40-60RPM (depends on the size). Below that speed they are designed to statically seal whereas most others are not.

HTH

Hambini

What does this mean?

Thanks in advance

NTN LLU bearings seal very well statically, so if you took a bearing and dipped it in water, the level of water ingress is minimal. If you do the same with an SKF or FAG bearing, the sealing systems they use do not seal statically very well so you end up with water ingress.

The disadvantage is at low speeds the NTN LLU bearing feels "draggy" and it's only at about 40ish RPM where the NTN seal gap opens thereby reducing the friction to the same as the others.

Hence if you do a spin test where you get some wheels and spin them up to lets say 300RPM, as the wheel speeds slow, there won't be much in it until you hit around 60RPM, at that speed the NTN wheel will slow down dramatically in comparison to the others as the seal is starting to go towards a static seal and closing the gap.

Hope that helps

Hambini

[pdlpsher1]

Thanks again Hambini for your informative posts.

[Gearjunkie]

Interesting about low speed NTN friction.

I have (thanks to a fellow WW member based in Japan) NTN bearings in my Alchemy Elf front hub and they spin as well in the stand (low speed) as my Campag Bora Ultras do - ie: for ages.

[pdlpsher1]

Interesting about low speed NTN friction.

I have (thanks to a fellow WW member based in Japan) NTN bearings in my Alchemy Elf front hub and they spin as well in the stand (low speed) as my Campag Bora Ultras do - ie: for ages.

Do you know if your NTN bearings are LLU or LLB? Mine has a lot of drag but I hope the drag will decrease over time. The Bora has a lot fewer seals and the wheels have been broken in.

If I understood Hambini the wheel spin test is not very indicative of real-world friction.


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[hambini]

Interesting about low speed NTN friction.

I have (thanks to a fellow WW member based in Japan) NTN bearings in my Alchemy Elf front hub and they spin as well in the stand (low speed) as my Campag Bora Ultras do - ie: for ages.

Do you know if your NTN bearings are LLU or LLB? Mine has a lot of drag but I hope the drag will decrease over time. The Bora has a lot fewer seals and the wheels have been broken in.

If I understood Hambini the wheel spin test is not very indicative of real-world friction.


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The drag won't ever decrease, it's the way it's measured. If you are riding along at 30km/h, the difference between LLU and LLB is small. However if you are doing only 1km/h the difference is about double because the LLU bearing is not going fast enough for the seal to come away from the inner race.

By spinning a wheel in free air the bearing is also unloaded so it will give you a false reading. What I am trying to say is the perceived drag is usually not real.

Hambini

[pdlpsher1]

Thanks Hambini. Do you prefer LLUs or LLBs bearings as wheel bearings? I have a wheel that uses Enduro LLBs as the stock bearings. Should I keep it as LLB or go for LLUs? The wheel is still new so I can’t tell if water/dust intrusion will be a problem. I don’t ride in the rain. Also what’s your opinion on removing seals? On my Campy/Fulcrum freehubs the inner seal has been removed on both 6803 bearings. But on all other bearings both seals are intact. Thanks again.


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[hambini]

Thanks Hambini. Do you prefer LLUs or LLBs bearings as wheel bearings? I have a wheel that uses Enduro LLBs as the stock bearings. Should I keep it as LLB or go for LLUs? The wheel is still new so I can’t tell if water/dust intrusion will be a problem. I don’t ride in the rain. Also what’s your opinion on removing seals? On my Campy/Fulcrum freehubs the inner seal has been removed on both 6803 bearings. But on all other bearings both seals are intact. Thanks again.


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If you are riding solely in dry conditions and want to go fast, the best thing to do is get open bearings and use a light oil for lubrication. They will need more maintenance but that's the cost of it. For day to day with minimal maintenance LLB would do the job. HTH Hambini

[Gearjunkie]

For what it's worth, mine are LLB.

Cheers
GJ

[pdlpsher1]

Thanks everyone who answered my questions.


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[TheKaiser]

If you are riding along at 30km/h, the difference between LLU and LLB is small. However if you are doing only 1km/h the difference is about double because the LLU bearing is not going fast enough for the seal to come away from the inner race.

Hambini

This whole seal lift topic is an interesting, and infrequently addressed aspect of bearing drag. So I get that you are saying an LLU seal will lift of the race slightly at between 40-60rpm, thereby causing a reduction in drag. What force is it that causes this lift?
By that, I mean is it part of the sliding friction dynamic, something having to do with the churning of the bearings within, or something else?
It's not simply centrifugal, is it? If it was, then it seems it would only apply to hub bearings, not BBs, as on a BB the outer race and seal assembly is stationary.

[PLuKE]

Very interesting thread.

Where in the UK, can i source the NTN LLU bearings?

[hambini]

If you are riding along at 30km/h, the difference between LLU and LLB is small. However if you are doing only 1km/h the difference is about double because the LLU bearing is not going fast enough for the seal to come away from the inner race.

Hambini

This whole seal lift topic is an interesting, and infrequently addressed aspect of bearing drag. So I get that you are saying an LLU seal will lift of the race slightly at between 40-60rpm, thereby causing a reduction in drag. What force is it that causes this lift?
By that, I mean is it part of the sliding friction dynamic, something having to do with the churning of the bearings within, or something else?
It's not simply centrifugal, is it? If it was, then it seems it would only apply to hub bearings, not BBs, as on a BB the outer race and seal assembly is stationary.

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.

SKF and FAG seals (both good), have a permanent light touch so they have less drag at finger speeds. The NTN would be classed as a heavy touch.

HTH

Hambini

[vinuneuro]

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.

SKF and FAG seals (both good), have a permanent light touch so they have less drag at finger speeds. The NTN would be classed as a heavy touch.

HTH

Hambini

Thanks. Where is NSK on the spectrum of static seal force?

Very interesting thread.

Where in the UK, can i source the NTN LLU bearings?

hambini.com

[hambini]

@Vinuneuro

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