Head tube bearing in my 1960s Carlton

[raleighnut]

Thanks Cycleops for the useful diagram.
I had no idea how the quill and the wedge worked to secure the fork steering tube.
I assume that the fork steering tube will drop down as the wedge releases, and that I'll be able to lift out the quill with the wedge on the end of it.
I have been worried about the lubrication of the head bearings.
It's something I never did in all the time I've had the bike.

One of the reasons I wanted advice is because I remember watching someone else do a bike repair when I was young.
He soon had ball bearings all over the floor.
Useful advice.

So - Thanks everyone for your help.
The quill stem bolt on mine is a hex bolt rather than an allen-head bolt.
I'll get some good penetrating oil on it tonight, and hope it's not too tight.
Fingers crossed.

If it has a bolt it will most likely not have a wedge at the bottom but a slot and bung, the remove in a similar way though.

 

[Ajax Bay]

the threaded headset wedge system really is a bizarre bodge - but works

And since it (quill stem) 'worked' for millions of cyclists for many decades (?) and still does for millions of bikes, I think describing it as a 'bizarre' and 'bodge' is a commentary on your appreciation for a simple engineering solution. The wedge has to be made of steel/iron as it has to be threaded for a steel bolt and is engaging (friction) with a steel steerer tube. These tubes don't get stuck by the wedge, they get stuck between the steel steerer and the alloy quill stem.

 

[Johnsco]

The fork will remain in place when the wedge releases. The wedge only holds the stem, the fork is held by the nuts threaded at the top of the steerer.

After I had written post #8, I read the Sheldon Brown link.
I realised then that I would have to undo the large nut at the head of the steerer to release the forks and get at the bottom bearing ... if I am brave enough.

Yes - It does appear to be a bizarre "bodge".
My dad was a very experienced cyclist (time trials / road races).
He taught me many things, although he was a joiner, not an engineer.
I had never heard of the wedge method of securing the steering tube to the stem.
But ---- It's been used for many years.
If it ain't broke, don't mend it.

Thanks everyone.

 

[C R]

I must say I like the threaded headset design better than the A head because of the way that the fixing of the stem is independent from the fixing of the fork.

 

[Blue Hills]

And since it (quill stem) 'worked' for millions of cyclists for many decades (?) and still does for millions of bikes, I think describing it as a 'bizarre' and 'bodge' is a commentary on your appreciation for a simple engineering solution. The wedge has to be made of steel/iron as it has to be threaded for a steel bolt and is engaging (friction) with a steel steerer tube. These tubes don't get stuck by the wedge, they get stuck between the steel steerer and the alloy quill stem.

I think praps you are being a bit prissy. I have several bikes with them, have taken apart and serviced a few, have sorted issues on tour with one. I like them.

 

[raleighnut]

Not to mention A-head stems look shite on a Road bike, they do look good on a 'rufty tufty' MTB though, especially one with 'triple clamp' forks like my Saracen.

 

[rogerzilla]

And since it (quill stem) 'worked' for millions of cyclists for many decades (?) and still does for millions of bikes, I think describing it as a 'bizarre' and 'bodge' is a commentary on your appreciation for a simple engineering solution. The wedge has to be made of steel/iron as it has to be threaded for a steel bolt and is engaging (friction) with a steel steerer tube. These tubes don't get stuck by the wedge, they get stuck between the steel steerer and the alloy quill stem.

Lots of stems have alloy wedges or expanders. Some Cinelli stems have alloy bolts, if you're brave.

 

[Ajax Bay]

Lots of stems have alloy wedges or expanders.

Example please, just for interest.
Poor choice of material for purpose imo, and can only be for (invalid) weight weeny reasons. And as for alloy bolts (in tension):

 

[rogerzilla]

The Nitto UI-12 that turned up this week has one, Cinelli expanders are alloy (with a finer thread too!). They are pretty normal on the more upmarket stems. I'm with you on alloy expander bolts.

 

[Johnsco]

Excuse my ignorance (perhaps) ... BUT
Are we talking about aluminium-alloy bolts - Certainly not a good idea with a fine thread ...
OR
Are we talking about "high-alloy" steel bolts, where reduced section-thickness, including hollow sections, can reduce weight while maintaining strength, and fine threads are quite realistic ?
It is quite common for to find high-alloy steel tie-bars or tie bolts waisted in the centre with a larger section at the ends for either threads or bolt heads. The transition between the thicker and thinner section is usually radiused so as not to provide a stress raiser.
Certain suspension components or motor vehicles are of hollow section for weight-reduction reasons.
Stronger materials on bike components

 

[Ajax Bay]

A (very) few quill stems, as Roger has pointed out, use an Al alloy wedge/expander (cylindrical - see Sheldon link) but the long bolt is (almost) invariably steel.
To pique your technical enthusiasm, decent steel frames are made with double or even triple butted tubing and a good wheel will use double butted (as opposed to plain guage) spokes. The threads on spokes are rolled not cut to reduce the risk from stress risers.

 

[midlife]

Lots of stems have alloy wedges or expanders. Some Cinelli stems have alloy bolts, if you're brave.

BITD we tightened the expander with a steel bolt..... And then swapped for the alloy one lol. Good job titanium came along

 

[Johnsco]

The threads on spokes are rolled not cut to reduce the risk from stress risers.

This is also common on critical aircraft components.

Thanks for explanations.

 

[Johnsco]

I eventually plucked up the courage to sort the head bearings on the Carlton.
The head had become noisy again on bumpy roads.
It quickly became clear what the problem was ..... and it was not as serious as I feared.
I carefully unscrewed the lock-nut and removed it and the carrier bracket for the brake cable.
The upper bearing race had become quite loose.
I very slowly and carefully unscrewed it.
The upper bearing was not caged and I found that the it was short of about 4 ball bearings.
Fortunately, the grease had not dried out and the bearing races appeared OK.
Pretty-clearly, this had been the problem.
I cleaned out and re-greased the bearing races.
At the same time, I carefully ran some lubricating oil down the tube until it ran out of the bottom bearing onto the fork crown.
I decided that should be enough for see the bottom bearing right.
I filled the upper bearing with new balls ... 5/16 inch diameter ... and stuck them in place with plenty of LM grease.
I then carefully wound down the upper race, making sure not to dislodge any of the balls.
How tight to fasten it ?
I made contact with the balls, then, holding the upper race with a rag, I tightened it by hand while turning the steering from side to side to seat the bearings.
Using finger and thumb only - I tightened it as much as I could - making sure that the steering did not start to bind.
I then replaced the bracket and tightened the lock-nut, making sure not to alter the position of the bearing.
Well - That's my educated guess how to do it.
I've given it a good road test today.
There's no clacking from the head tube when I go over bumps.
There's no stiffness in the steering.
Fingers crossed !!

 

[Ajax Bay]

Your lower bearing (fork crown/bottom of head tube) would have been in a worse condition that the upper one you've just sorted. Though hopefully it still has a full number of bearings. "Carefully [running] some lubricating oil down the tube until it ran out of the bottom bearing onto the fork crown" may give temporary satisfactory performance but you need to 'finish the job' - and this lovely old bike deserves this tlc. You need to pull the fork out of the headtube, clean everything up, replace the bearings in the lower one as well, loads of grease (just as you describe above) and reassemble.
The test of whether the headset is tight enough (with the locknut tightened) is 'if I apply the front brake and push forwards/backwards, is there any movement?'. If 'yes' tighten a bit but only till the steering exhibits friction, and then loosen off a bit (and lock). If 'no' and the steering does not exhibit friction, go ride.