Everything You Need To Know About Bearings | Hambini Engineering Special
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Everything You Need To Know About Bearings | Hambini Engineering Special

October 14, 2019


Welcome to a special episode here
on the GCN Tech channel because I’m joined by a legend in the
world of bearings or it certainly is for me and I reckon by the end of this episode,
he’s going to be a legend for you too. Welcome, Hambini.
-Thanks very much for the introduction. I think you might have been a bit over the top
but I’ll give him my best show. Cool, okay. Hambini himself
is actually an engineer by trade so he certainly slightly more qualified
than myself to talk about bearings this size. Well, you’ve submitted your questions
for us to answer, so we’re going to do just that. Now, one of the most common questions we get
actually is what’s the difference between the low-end bearing and a high-end
bearing in terms of drag or resistance when riding along
and I’m pretty keen to know this because I love the marginal gain
hearing that, so hit me with the stats. If you get a bearing this typically no name
versus something that’s named and isn’t a fake, the typical drag for everything
so that’s your bottom bracket and freewheel, the hubs, the jockey wheels is about
somewhere between 7 and 10 watts. Okay. Well, that’s up to me.
-It does. The vast majority of the drag
comes from the seal. It’s nothing to do with the bearing material
whether you buy ceramic or steel. It’s almost irrelevant. The vast majority
comes from the seal and if it’s contacting. The next proportion of the drag
is from the lubricant you use. If you use like a thin oil which
is less viscous, you’ll have less drag. The problem with doing that is you will
have to maintain it more frequently. Some of the top cyclists,
I think it was Alberto Contador, he used to take all the seals off
and put in a drop of mineral oil. That’s what his mechanic used to do to reduce
the drag to the absolute bare minimum. What’s the difference between
a cartridge bearing which is what these types of bearings
are commonly known as in the bike world up against a cup and cones style bearing?
A cup and cones style bearing is what– Well, traditionally, in the bike trade,
we used to use for– well, forever until the invention
of these bad boys. Yes, a cup and cone bearing is in effect and angular contact bearing
that is constrained. An angular contact bearing
that we’ve sliced in half- -That’s so cool.
-is one of these. Yes.
-What we’ve done is I’ve tried to draw them pretty poorly, try and draw pretty poorly and a section
through it and that’s what you see here. At the same time, this type which is what’s
commonly known as a cartridge bearing– Again, I’m drawing a section through here
or describe what the difference is. The first obvious one is when you look
at that one, it’s symmetrical through the axis, so you can go both ways, looks the same.
This one, the angular contact is not. One side is the cup which is this side Yes, that’s better in it. The cup is the inner race and the cone
is the outer race. Now, unfortunately, in order to do this little prop,
I have to weld in there. That’s a small bit of metal,
it shouldn’t be there. If you show them that piece,
you can see the shape is not symmetrical. What happens is on the cartridge bearing, because it’s symmetrical,
it takes a load in either direction. You can run it in either way and
a lot of manufacturers use that ability. Notably SRAM with its GXP bottom bracket. One bearing is fixed
and it takes a load both ways whether you’re pedaling
with your right foot or your left foot. All the axial load is going through
the non-drive side bearing. The turning load which is called the radial
load is being transferred on both, but the axial is just one on side.
When you look at the angular contact bearing, the ball for the same outside diameter
is bigger. The contact angle which is called
the alpha angle, which is this angle here, some bearing manufacturers put
the angle slightly differently, but I’m drawing like this for consistency, is much further towards an axial direction
than the cartridge bearing. The cartridge bearing is designed to take
radial load and not much axial. The angular contact
will take a lot of axial seeds. This is called the load center
where the two lines cross. If you had the bottom half of the bearing
and drew it across, you would have a load center and be offset
by X millimeters, maybe 20 or 30. The actual load carrying capabilities
significantly more. The original question was, what was
the difference between cup and a cone. A cup and cone is an angular contact bearing.
It’s just unconstrained. A cup and cone doesn’t have
the metal cage holding the bowls and in place as the true angular contact does. How’d you know what size bearing you need
for those DIY replacements at home? The best way to do it is to take it out
and measure it. If you can’t do that and you’ve just got
the numbers on the outside to go off, you can decide on the bearings. Once again, easiest job is to go into Google
and just type the number in, it’ll give you it. For interest’s sake,
I’ll go through it on this board. The first number on a four-digit bearing
will typically be a six or a seven. A six is a deep groove ball bearing, seven is angular contact. The second number is in effect
the outside diameter of the bearing. It doesn’t follow any particular coding. It just goes from 7, 8, 9, 0, 1, 2 and so on.
That’s just getting bigger. The 06 is the ball. Balls will go 00 which
is 10 mm. 01 which is 12, 02 is 15, 03 is 17, 04 is 20. When you get to 04,
all of the subsequent numbers, you just multiply by five. 05 is 25 and 06 is 30. From this, the BB30 bearing is six
which is deep groove ball bearing. The eight is just the second number
in the outside diameter series and it’s 30 mm ball, so it’s 30 X 42 X 7. This is not something off of a tank bang
because you’ve gone through that so fast. All I’m thinking is, “Hey, it doesn’t really make
any sense.” I’m not going to worry about that because I think for most people out there,
they’re not really going to look into that, in too much detail, are you? If you can look at the side of the bearing
on there for those numbers, basically, and that’s what you’re going to be looking for. How do you tell when a bearing is worn and when
is the best time to replace it if you can’t tell? From my own experience
or knowledge about bearings, at least if you were to cut it away like this,
you can see when you’re turning it, the different parts of the bearing
are moving at different speeds which I guess means they’re wearing
at a different rate. As Jon’s turning the inner race, this bit which
obviously, this is not a complete bearing. As the speed to that rotator
is called the inner race frequency. If you were to take a bottom bracket example,
typically, some people are going to pedal it. To make the numbers easy, let’s say, 60 RPM.
The reason I picked 60 is because it’s a minute. In a minute, you’re going to go 60 times. The inner race travels at a certain speed
and gives you a frequency. The balls, these things will turn
at a certain frequency. The whole thing is turning on
the fundamental train frequencies. The fundamental train frequency
is the rate that effectively the cage is going around them.
The cage rate is slower than the inner race. You’ve also got ball-spin frequencies
on the inner race and ball-spin frequencies on the outer race. There’s quite a lot of frequencies in there. Inevitably, the failure mode
on a bicycle bearing is usually from an external factor
such as contamination. You get a bit of grit in there,
the ball spins around and then grinds itself
into one of the races. That’s how that fails. If you are going to regrease your bearings, what sort of grease should you use
and how much? Because certainly when I used
to regrease cup and cone bearing, headsets that sort of thing, I would pack
as much grease in there as possible. Probably to make the job a little bit easier
of loading all those bearings and making they didn’t fall out around
on my mom’s best carpet or something like that which I got
in trouble for. Any tips or advice there. Bearing manufacturers, the big ones, ?SKF. Those people, they’ll give you guidance
as to how much grease to put it. Typically, it’s a third.
A third of the total volume should be greased. Say, this bearing here.
I’ve gone ahead, I’ve decreased it, tried to air because I will use some air,
glass over there. I’ve even used a hairdryer it before
that just to get it perfectly dry. Hopefully, that’s all right to do.
-Yes. Okay, good. Not going to get told off that one.
I should go, say, a third of the way round, should then just spin it to get it in there
just a little bit more? It’s a third of the total volume.
-Okay, right. You don’t necessarily need to go a third of the
clock face, just a third of the total volume. Just to spread it out evenly
but just at third. If you overfill it, what happens is the balls won’t be able
to move very well so you’ll have more friction. The aim of the grease is, as the thing warms up,
it actually turns to oil. It goes soft and becomes more of a lubricant
and that’s what you’re rolling in. What sort of grease am I going to put in there? General guidance is lithium grease.
It is based on a scale, the grease type, of NLGI and something like a one on that scale,
would be the one to go for. It doesn’t really mean a lot to me
but I guess if you’re really into it, you could have a little look and research it. Have it on a data sheet and it’ll tell you. Now, I have to say, you mentioned earlier on
about it when the grease turns into a liquid when it gets up to a certain temperature,
that sort of thing. I recall I think it was either
Fabian Cancellara or Alberto Contador who we’ve already spoken about, the
roof seals, and bearings, that kind of thing. I have this weird feeling
that one of them had a guy at the side of the mechanics truck
who used to spin wheels before he raced in time trials
to get that lubricant turning into a liquid. Just getting the grease into a liquid. Is that going to give you,
do you reckon, hypothetically speaking, significantly better or less wrong
resistance in the bearing or not? It’s going to be so marginal, isn’t it? For the first few kilometers, probably.
The thing is, at their level, the difference between winning or losing
is that sort of attention to detail. If you’re just out smashing it on the weekends,
then it doesn’t matter. Yes, we’re not going to be like Formula 1 pits,
are we? We warm up the tires. I can’t imagine you sat in your garage,
me sat in mine before we go out, spinning our wheels to make sure that the bearings or maybe you do. No.
-Okay, that’s good. I don’t even wash my bike.
-Another cracker of a question here. Andrew Montgomery,
do ceramic bearings last forever? Thing with ceramic bearings on a bike is, they are technically
or the vast majority of them are hybrid. The balls in them are silicon nitride
or something along that lines. They’re very hard material
but the races aren’t. They just generally tend to be steel.
If you have a very hard material rubbing against a relatively soft material,
what happens is, it wears a track inside the bearing. While the balls don’t fail,
the track that it develops, does. It would be akin to getting a locomotive
and running on a road. The rails are significantly harder than
the tarmac so it would cut a hole in it. What you want is materials
that have a hardness that’s much nearer to each other
and they will last longer. Okay, so that’s the thing. A lot of people out there
and I’ve fallen victim to this in the past you see a ceramic bearing offered really,
really cheaply and you think, “I’ll get that.” It’s like £2 or something. Crazy low price. Ultimately, that is not going to last, is it?
I think we can safely say that. There’s a couple of things
with bearings as a whole, not just specifically ceramic. One is fakes. There are a lot of fake bearings on the market. You wouldn’t believe how much have crossed
my desk and the desks of my colleagues. In that sort of size,
so we’re not talking small bearings. That’s baffled me really because
I’ve never seen a bearing this size– well, I probably have but in the back of some big
machine or something like that in a factory. I wouldn’t have thought that someone would
be making fakes for that. I would have thought– because I’m, I supposed, obsessed with bikes, I would have thought,
“They only make fake bearings for bikes.” The fake bearing for a bike is probably
only going to cost £2, $3, €4, whatever the currency is
but one of these bearings costs a lot. If you can fake one of these, then the margin
that they get is significantly greater. In terms of the bike,
when you buy the fake bearing, what you’re getting is a bearing
that doesn’t have the dimensional accuracy. What they rely on is people
not having the instrumentation and the measuring gear to be able to tell
that the bearing is not quite right. Now, one of the most common questions
actually you see on the internet is someone who says,
“I’ve had a bottom bracket for 2,000 kilometers and it’s already worn out,” and then someone else will have exactly
the same bottom bracket and they’ll say, “Well, I’ve been riding for five years
that bottom bracket and it’s still in perfect condition.”
We’ve got a graph. What’s this graph all about? One of the things that you have
in engineering principles is load versus life and that’s
typically called an S-N curve, but I’ve simplified it here
for the benefit of the viewers. Load is along the y-axis and cycles is along
the x-axis. The x-axis is a logarithmic axis. It’s going up in multiples of 10. It’s not
linear 10. We’ve got 10, 100, 1,000, 10,000 and so on. If you are pedaling with a very,
very low cadence but massive torque, you’re putting a lot of load
into those bottom bracket bearings. You’re be over here. You actually get less life
than someone who spun their cranks up and was putting less load,
but more RPM through. The limiting factor on a bike is not the speed
because it’s whether it’s 60 RPM or 100 RPM, that’s nowhere near the limit of the bearing, but the torque
that you put through the bearing is. That differential is. The person who
is only getting 2,000 kilometers if they are on the heavy side,
then they’ll be that way. The person who’s lightweight
and spinning at 120, they’re putting significantly less
torque rate so they’ll get more cycles and it’s just the way it is. You got like a track sprinter.
They’re going to be– Well, somewhere around here, aren’t they?
-Yes. You’re climber, you’re real lightweight rider,
they’re going to be– Well, hopefully, if they’re spinning,
away they’re going to be somewhere, hopefully, down there, aren’t they?
-Yes. Now, finally then,
what about maintenance of bearings because not everyone likes to get
their hands dirty and grubby like, “That’s in the workshop,” do they? What can the viewers do to try and
get longer life basically on their bearings? There’s a few things.
The biggest one is contamination. Contamination will make the life
of the bearing shorter, that’s the biggest one. The other one is when you come to install it,
when you install bearings, you tend to have a press
that presses directly onto the bearing like a BB30 press or something like that. One thing that people start aspire to
because I think it’s good, is having stainless steel presses. Stainless steel is a pretty terrible
material in some characteristics. It has this characteristic calling, it goals. That’s when it friction welds itself
to another material while the friction welds itself.
You can have an issue where you put the bearing in
and as you’re tightening the press, it goals on the surface, so it’s trashing
your bearing before you even get started. I’d recommend you use either plastic
or aluminum or if you are going to use a stainless steel, make sure it’s got a bigger clearance
than you would normally have. Another thing is when you’re pushing
putting the bearings in, the most common failure mode I’ve seen
is poor alignment. Alignment specifically embossed
and brackets because unlike wheels which tend to be machined on
the lathe bottom bracket is quite a lot, a lot of time on carbon bike frames
are glued together in the middle. What happens is you’ve got two bearings
and they’re slightly misaligned. If you take these two as an example, you might
have, what’s known as parallel misalignment. If the right hand is the drive side of the bike and the left-hand side is the non-drive side,
that’s parallel misalignment. They’re completely offset
or you can have angular misalignment so the center lines are in the same place
and won’t tip. If you have any of those things
and you’ve got moving parts in there, then what the crank tries to do
is it tries to straighten itself. It can only straighten itself
through the bearings because that’s the only point of motion and you’ll tend to do that which
you called fretting. Bearing is really, really hard. Carbon isn’t. It’ll just wear the whole out.
You need to worry about that. In terms of routine maintenance, I personally don’t take the seals off
to repack the grease. I just change the bearing. Do you think the life’s gone, basically?
-Life’s gone. Plenty of people take the seals off
to grease them. I certainly won’t recommend
knocking them out. Guilty. A massive thanks to Hambini today
for popping in and telling us all about bearings
and all sorts of graphs and some of that. I’ve learned a hell of a lot today
and I hope you have too. After all, if he wasn’t here,
I wouldn’t have had some of these. How cool is that? Now, remember as well
to like and share this video. Give it a big thumbs up.
Tell your friends about it especially if they’ve got bearings
are absolutely knackered and you need to just reaffirm the point,
they’ve got to replace them. Also, remember to check out the GCN shop at
shop.globalcyclingnetwork.com. We have a whole heap of products for you
to check out. What video should they watch now? Maybe they should watch you
pressing in a bottom bracket. Hopefully, I did that one right. I’m pretty sure
I did. It’s going to be just here.

Only registered users can comment.

  1. Top vid guys.. what a pleasure to listen to someone who knows precisely how to explain a technical topic to simple cyclists.. bang on..

  2. Love this video! As a recently graduated Mechanical Engineer, I am so delighted to see this presented so well! Kind of makes me want to upgrade the bearings on all my bikes!

  3. I know the physical difference between cartridge and cup/cone, but what are the pros/cons of each type?For instance why does shimano always have cup cone in hubs and mostly everyone else go with cartridge ? Is there an advantage either way?

  4. A great input. He obviously didn’t know the amount of time you’ve spent plugging Ceramic Speed. Basically take your seals off and relube regularly if you’re that interested in saving watts AND saving pounds.

  5. I've been watching Hambini for awhile now. He knows his stuff, keeps it simple, and gets rid of all the B.S. Hope to see him more on the GCN network of channels.

  6. so who is actually using full ceramic bearings (which manufacturer) and would these be better for long life, and what about running them dry for races?

  7. You have to bearing mind that you won't get back these 20 minutes on the bike even by following each of the recommendations.

  8. What many people dont understand is that sealed cartridges come in a wide variety of qualities. Many components have the cheapest chinese crap installed. Many companies spec bearings that are not designed for the loads involved. No bearing is maintenance free! Everything wears out. Especially if its not installed correctly or the hole it goes in is not manufactured correctly. This is the main problem with cartridges.Machining tolerances for proper bearing installation are in tenths of thousandths of an inch!

  9. Cup and cone, angular contact type loose bearings are still best for adjustability, economy and ease of maintenance( $ cone wrenched vs press tools$$$$$$$)
    This is why Shimano and Campy still use them.

  10. Hambini doesn't mess about, I wonder what was edited out. Shame we didn't get to hear about the racing orange bottom bracket, they had right infront of them. The main point Hambini is trying to make is that the premature end of life of a bearing will affect performance.

  11. Great video, watched it loads of times and learned so much…I’m now a Hambini fan, and have signed up to his You Tube channel…What a guy !

  12. Press fit bearings suck! The cycling industry took something that wasn’t broken and fixed it! Threaded bottom brackets should become the standard. I just bought a Specialized Roubaix with a threaded bottom bracket. Finally, some common sense! Thanks Specialized!

  13. I've been looking for this video since I heard Hambini mention it in his channel. It's one of the most valuable in terms of information. Perhaps you will recruit Luescher Technik for a session?

  14. this guy is the bearing genius ,he knows all especially How crappy BB30 is and why !! QUIT BEING CHEAP BIKE MAKERS !!! THREADED BB S ONLY!!

  15. Can we have Hanbini on again talking about various issues. Wheel and spoke fatigue, and bike aerodynamics including wheel aerodynamics what works and what does not. Hub servicing etc.

    The guy is a legend and very entertaining to boot.

  16. I have your bottom bracket in my P5x – best thing I've bought to the bike. Those BBs should be factory fit in every pressfit frame 😉

  17. Recently found Hambini's channel which brought me here. If you really want to geek out on Aerodynamics and other engineering science, I highly recommend. The best part is that it debunks alot of the marketing claims e.g. Ceramic bearing BB's – wish I seen it before I bought mine….

  18. You never re-grease bearings after they feel bad or rough. Too late. Regreasing is a maintenance step performed when it still spins well, but hasn't been regreased within a certain maintenance interval.

  19. Too much science but there was not much help.

    Maintenance? Replace
    Greasing? Don't bother
    Improve life? You can't

    Pretty useless guest to be honest

  20. The gcn bloke was lost and confused from about a second in tbh,he had the vacant look on his face most of the video

  21. GCN has access to some of the most educated people in the various industries covering the different parts of cycling,
    who explain clearly the principles involved. This video is a peach, and very enjoyable.

  22. Great to see Hambini nerding out on super specific details of bearing types, codes, and race frequencies.

    But I couldn’t but notice that questions being asked were not actually being answered!

  23. I've heard of ceramic bearings, are they any better than the metal balls one in a cage that my Peugeot Versailles has ?

  24. People talk about marginal gains because team sky did it but they forget team sky had the best riders and overall team in general. They could have had much worse bikes and still won!

  25. CUP AND CONE ( RIGHT DIAGRAM) NON SYMMETRICAL ANGULAR CONTACT BEARING & CARTRIDGE BEARING (LEFT SIDE DIAGRAM) Did any one understand the difference or it's importance? I think I need some close ups because I had no idea what he is referring to or what he welded in to keep whatever together! That had to be the wort explanation ever. OK so here is where I go for a replay at 5:14. Because really no clue!

    2:55 " when you look at that one it's symmetrical through the axis", Which one? you got a close up of both bearings! I don't see a difference, do you see a difference which is symmetrical and which isn't? John is holding the bearing on the left and talking about the bearing on the right diagram and Hambibi is holding the bearing in the right, but talking about the bearing in the left diagram! And which is which ? After replaying from 2:05 to 4:05 several times (5 times I think) I started taking notes. Then while taking notes I stopped and started it another 5 times at least.

    3:46 " one bearing is fixed…." how is a bearing fixed? I thought bearings rolled ? " all the axial load is going through the non drive side bearing" What is an axial load? And why is that important, good or bad? 4:32 " Is much further towards and axial direction than the cartridge bearing…." What is? And what is the importance of an axial load compared to a cartridge bearing radial load? You can tel at this point that John has no idea what he is talking about and barley mumbles a "yeah". And the clip had been edited at that. So that's the difference! But why or how does it matter?

    I've spent at least 30 minutes trying to understand and follow a 3 minute section of this clip. I like Hambini and subscribed to his channel, but this is just the most uninformative and confusing thing I have ever heard him or you guys explain.

    7:27 The question was when is it time to replace the bearing….. lots of explanation on how a bearing moves, but he never even comes close to answering the question. So what does 1/3 grease volume look like, John has no idea and neither do I. Grease type? Does he answers the question? Says something scientific that John admits he doesn't know what it means. So the answer is look on line at a data sheet? A data sheet for your bearings, I've never seen one have you? So yes spinning your wheels will make a marginal difference for the first few K's! So there are a lot of fake bearings. How do you know the difference? Bearing life span! Yeah he answered that. But he never says that more torque equals less life. Bearing maintenance longer life, to use a better press for installation, but he just said the #1 determiner was contamination. So the question is how do you stop contamination. He says the best idea is to just change the bearing, but he never answered the question previously of how you know when to do that. So basically you need to do another segment where jon answers these questions for the average idiot like me and not for the engineers who cycle.

  26. "Sliced in half" yet he holds up 3/4 of a bearing. If this guy truly is an engineer, don't let him get anywhere near the quantity surveying department!

  27. So refreshing to hear from a proper engineer especially one who can articulate the answer in such a clear and no nonsense way. Love it!

  28. I have sealed ceramic bushing in my jockey wheels. I have a shimano deore xt rd-m735 sgs. That's from 1990. Pretty revolutionary stuff. I took it apart to clean and regrease about 6 months ago, everything is still functioning really smoothly. Shimano really knows how to make quality bike components.

  29. Note most every automotive grease for general use in hubs etc. will be NGLI #2, okay but a bit thick for bike bearings, and unless synthetic will get even stiffer in cold temps. If one wanted to "prewarm" bearings, a heater like a hair dryer or small torch works better. Ratvision.com tested various bearings, and only the U.S. quality steel balls withstood triple the compressive force that shattered every ceramic, and Chinese steel as well – do you know who made your bearing? The biggest shortcoming to most "modern" BB systems is that, compared to the ubiquitous Shimano "Canister" sealed units which housed the crank axle and both side bearings in a single closed, pre-aligned system that only needed to be nested into the frame by threading one side and meshing with a threaded guide on the other (guaranteeing perfect parallel bearing planes perpendicular and pre-loaded to the axle), external cups begat the same issues as old-fashioned cups dependent on proper, meticulous frame threading and facing to assure each side is in alignment. With the inevitable loss of precision in this mode of installation, bearings will drag and wear prematurely regardless of material or lubrication, and in every way except larger crank spindle diameter, a retrograde step dramatically decreasing durability while raising costs and service frequency.
    Note too that for decades, most Campy hubs had a ring band hugging the hub between the spokes – this covered a small hole, which can be used to optionally drip oil down inside the hub, when the bearings have been cleaned of any other grease. Great for time trials and track events, but not so much for ordinary riding. I doubt anyone has ever argued convincingly that a single race was ever decided by virtue of lubricant choice – unless a bearing seized up.

  30. Jon & Hambini: extra special GCN Tech. If you can do a show either on Hambini making a BB or GCN making one from the designs Hambini puts in the open source space then that would be fantastic.

  31. @3:00 Incorrect the cup IS NOT the inner race. The cup is the outer race, the cone is the inner race. Jesus, everyone here on this guys nuts thinking hes some kind of genius, and the dude does not know a cup from a cone. WOW!

  32. Hambini is the man!
    But GCN, please don't be so lazy with your videos, how about getting the cameraman to get some CU's or cutaways of the items? Be nice to actually see a closeup of the cross section cup and cone and cartridges and maybe spend a bit of time making some on screen infographics. Lazy production values. Tut tut! 😉

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