Cup and cone bearings and temperature

[rogerzilla]

I'm not sure how they coped in the olden days Adjust a BB perfectly at room temperature, put the bike out in a cold garage, and the BB becomes stiff to the point of binding. Do it the other way around, and the BB will actually develop play (it's not just grease thickening) at 20 deg C compared to 5 deg C. Shimano pedals do the same thing. It shows how a few micrometres are the difference between good and bad adjustment.

Also: don't build a winter bike in a warm kitchen!

[NickJP]

You need some of the modern cup and cone hubs that use aluminium for both axle and hub shell, so no differential expansion between the two with temperatures changes.

As someone who rides fairly large frames - around 160-180mm head tubes - I've noticed the same problem with headset adjustment on framesets that use a carbon fibre steerer fork in an aluminium frame. The temperature difference here (Canberra) between a hot summer day and a cold winter morning can easily be 50°C, and if the headset is correctly adjusted for summer riding, when winter comes along, the head tube shrinks by enough relative to the steerer to cause noticeable play in the headset.

[Paulatic]

I thought metal expanded on heating?
a warm assembly going stiff in cold doesn’t add up does it?

[pwa]

I thought metal expanded on heating?
a warm assembly going stiff in cold doesn’t add up does it?

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

[Jdsk]

I thought metal expanded on heating?
a warm assembly going stiff in cold doesn’t add up does it?

Are you thinking of the same material in both pieces, or two different materials with different coefficients of expansion?

Thanks

Jonathan

[KM2]

My brother used to set up a chainset such that it could be blown round. A good bb, chased and faced bottom bracket needed.

Are you sure the problem is just one of type of grease used. Thinner grease in cold conditions, same with’winter diesel’ same principle.

Ole Ritter had the grease removed from wheel bearings in time trials, just using oil.

“Sometimes” the modern use of sealed bearings doesn’t give the lowest friction.

[Paulatic]

I thought metal expanded on heating?
a warm assembly going stiff in cold doesn’t add up does it?

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

Never heard or seen that experiment but thank you for the insight. That’s like magic

[pwa]

I thought metal expanded on heating?
a warm assembly going stiff in cold doesn’t add up does it?

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

Never heard or seen that experiment but thank you for the insight. That’s like magic

A teacher performed it at school. The outcome is far from obvious, so he asked us to speculate on what would happen, given that we already knew that most materials expand on being heated. It turned out that the hole in the hoop got larger as the hoop was heated, and even though the steel ball was also expanding, it was not as much as the hole. I imagine the same would hold true for bearings.

And if you think about it, anyone who has seen a barrel or a wooden wheel for a cart made will know that the hoop of steel is heated to make it go over the barrel or wheel rim, then it shrinks and tightens on the barrel / wheel as it cools. A bearing race is a sort of hoop.

[Jamesh]

I thought metal expanded on heating?
a warm assembly going stiff in cold doesn’t add up does it?

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

That's the best way to fit bb30 bearings btw.

Cheers James

[Jdsk]

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

I'd never seen this as a science demonstration. I've just watched a few videos.

Of course they show the inner diameter of the ring expanding on heating, which is the part that might be counterintuitive.

But I haven't found one that shows what you're describing... the ball not fitting through the ring but then doing so when both are heated together...

Jonathan

[pwa]

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

I'd never seen this as a science demonstration. I've just watched a few videos.

Of course they show the inner diameter of the ring expanding on heating, which is the part that might be counterintuitive.

But I haven't found one that shows what you're describing... the ball not fitting through the ring but then doing so when both are heated together...

Jonathan

Yes, I did a quick look and couldn't find it, but that is what happened when the experiment was conducted at my school in the late 1970s. The ball and hoop were obviously matched so that the ball would nearly go through at room temperature and only required moderate heating of both to prove the point. An explanation followed but I don't remember it. Clearly the ball also expanded but not as much as the hole in the hoop. It must be to do with the particular way a hoop expands. Done in reverse, with cooling rather than heating, there could be a theoretical danger of a bearing getting tight. But then you would expect some increased friction which would generate heat......

[Jdsk]

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

I'd never seen this as a science demonstration. I've just watched a few videos.

Of course they show the inner diameter of the ring expanding on heating, which is the part that might be counterintuitive.

But I haven't found one that shows what you're describing... the ball not fitting through the ring but then doing so when both are heated together...

Yes, I did a quick look and couldn't find it, but that is what happened when the experiment was conducted at my school in the late 1970s. The ball and hoop were obviously matched so that the ball would nearly go through at room temperature and only required moderate heating of both to prove the point. An explanation followed but I don't remember it. Clearly the ball also expanded but not as much as the hole in the hoop. It must be to do with the particular way a hoop expands. Done in reverse, with cooling rather than heating, there could be a theoretical danger of a bearing getting tight. But then you would expect some increased friction which would generate heat......

Thanks

I don't understand why that effect would occur if their temperatures increased identically. But most ways of heating would make the ring hotter faster than the ball...

Jonathan

[KM2]

I guess the inside of a ring can only get larger/longer by making the ring a larger diameter.

[cycle tramp]

Do you remember the classic experiment that has a steel ball resting on a steel ring that is a tiny bit too small to let the ball through. The ball and the ring are both heated, so both expand, but the hole in the ring grows more than the ball, so the ball falls through. If you did it the other way, a bearing race would contract more than the balls within.

I'd never seen this as a science demonstration. I've just watched a few videos.

Of course they show the inner diameter of the ring expanding on heating, which is the part that might be counterintuitive.

But I haven't found one that shows what you're describing... the ball not fitting through the ring but then doing so when both are heated together...

Jonathan

Yes, I did a quick look and couldn't find it, but that is what happened when the experiment was conducted at my school in the late 1970s. The ball and hoop were obviously matched so that the ball would nearly go through at room temperature and only required moderate heating of both to prove the point. An explanation followed but I don't remember it. Clearly the ball also expanded but not as much as the hole in the hoop. It must be to do with the particular way a hoop expands. Done in reverse, with cooling rather than heating, there could be a theoretical danger of a bearing getting tight. But then you would expect some increased friction which would generate heat......

If you cool cartridge bearings in the freezer for a an hour or two they should be easier to fit inside the body of wheel hubs and pedal bodies. I've not had a chance to try this, as anyone else had ago?

[Jdsk]

If you cool cartridge bearings in the freezer for a an hour or two they should be easier to fit inside the body of wheel hubs and pedal bodies. I've not had a chance to try this, as anyone else had ago?

This works fine for all sorts of interference fits.

You can get a bigger effect with dry ice because it's colder. Think about whether there are any eg plastic components inside.

I wouldn't recommend liquid nitrogen if you're not used to handling it.

Jonathan