I will be fitting a new Headset into a steel frame and I have put the new Headset in the freezer, Is it an urban myth that it helps?
From a Physics point of view it should but does it actually help in "Real life"?
My home made press is ready and I have the knocking out the old headset tool, so should be good to go!

Yup, Alloy expands and contracts more than steel for a given temperature so if you freeze it, it will be a wee bit smaller that it normally is. When you bash it in (OK press it in carefully ) that cold transfers to the steel head tube, it will also contract, but not as much.

I must admit I tend to bash them in at normal temperature but nowt wrong with being extra diligent.

It does shrink if you freeze it, but not by much. Coeff thermal expansion for aluminium alloys approx 13 x 10^-6. Temp difference +15C to -12C gives total of 27C.
Diameter of headset say 45mm... total contraction 0.015mm. So not enough to make much difference with the tolerances of manufacture of parts like these.

Never bothered nor needed to. Waste of time IMO.

Thanks for the replies, this is the first time using the freezer, I have previously not bothered and just pressed it in, but as it is a nice Hope headset I thought I would try it.

ChrisF wrote: ↑Mon Aug 29, 2022 10:29 pm It does shrink if you freeze it, but not by much. Coeff thermal expansion for aluminium alloys approx 13 x 10^-6. Temp difference +15C to -12C gives total of 27C.
Diameter of headset say 45mm... total contraction 0.015mm. So not enough to make much difference with the tolerances of manufacture of parts like these.

That`s what I thought!!
Cheers, Rob

The biggest difference is that you will now be fitting it with numb fingers....

slarge wrote: ↑Tue Aug 30, 2022 7:48 am The biggest difference is that you will now be fitting it with numb fingers....

That's what I thought.....

It'll make a difference and wrapping a cloth soaked in boiling water round the head tube for a few minutes will too ... neither are really required but they can't hurt (other than frostbite). Also, a little smear of your chosen lubricant between the two can help stop them jamming and aid future removal.

chosen lubricant

which should be copper slip grease for non rotating contact parts [ headset bottom brackets etc ]

Also never bothered but I rather enjoy hitting things with a hammer

which should be copper slip grease for non rotating contact parts

To prevent seizure certainly but in this case it may not be the best thing to ease installation as it's a poor lubricant.

BIGGER HAMMER

Just a quick update, In a very non scientific experiment, The old headset ( in the frame 8 years) took a lot of whacks, brute force and ignorance ( a quality I am blessed with) with the rubber mallet on the removal tool to get the upper and lower cups out.
However.... the new headset from the freezer went in ( well lubed) no trouble, a couple taps to get it lined up nicely and then 3 or 4 more good ones to get it home.
Had the new headset been at room temperature would it have gone in so well? Who knows? Freezing it didn`t do any harm, but did it do any good. That will remain a mystery!

I would say that removing a stubborn set of cups is best done with a steel hammer on the race removal tool thing as it's all metal on metal so you get more of a shock on the old headset and it comes out easier. It might seem a bit heavy handed but I've never damaged anything other than my thumb yet

Agree with Phil, there's a time and a place for rubber mallets but this was ......

In the interest of scientific enquiry I think you should tap out one of the cups and press it back in at room temperature and report back to us.

ChrisF wrote: ↑Thu Sep 01, 2022 6:59 am In the interest of scientific enquiry I think you should tap out one of the cups and press it back in at room temperature and report back to us.

If I were to do that I would use a steel hammer next time so would not be a true comparison!