Road Fan

Hi, here's what I hope is a new topic, but I apologize if it is old hat.

I'm rebuilding my 1952 Rudge Aero Special, a 27" Reynolds-framed drop bar bike made by Raleigh in Nottingham, England. Current stage is to install the H/S cups and bearings, installing the fork. I've been told the head tube IDs are to be 30.0 mm, and mine are (actually 29.97 mm, if I can believe my Harbor Freight digital caliper!). Also, Park Tool says the maximum allowed interference in such a press-fit installation is to be maximum 0.2 mm (not 0.20 mm for some reason).

My fixed cups have OD of 30.28 mm, so the interference works out to 0.30 mm, theoretically too great to use if Park Tool is correct. Has anyone ever installed a HS with this much interference? The frame is labelled to be full straight guage 531, but the head tube sure looks seamed, peeking inside it! The head lugs are nicely brazed and 70 years old. Should I go ahead and use these cups? They MIGHT be the ones which came out of the frame originally, actually I think they are, but I didn't mark them carefully when I pressed them out and put them in the parts cleaner.

Am I really at risk of cracking my head tube if I force these in, with a pretty decent HS press? I don't have a convenient way of cutting down the ODs of the upper and lower fixed cups. Emery cloth sounds attractive, but I don't have a machine tool where I can chuck up the cup and work it with an abrasive, keeping it concentric.

FWIW, the bike frame size is about 54 or 55 cm c-c with 27" wheels. Overall geometry is long and laid back, a precursor to the Super Course and the Raleigh International of 1971.

Andrew R Stewart 

The easiest way to close down the amount of interference is to slightly open up the head tube, flap wheel on a die grinder would work. But I would first just try pressing these cups in and judge how they fit. With a steel HT that was undoubtedly brass brazed the chance of a future crack is quite small. What ever you do make sure all the other headset parts go with the cups Andy

hokiefyd 

Sheldon's page says that both 1" Raleigh and 1" JIS cups should be 30.0mm. You said you weren't sure if the cups you have are original or if they even came out of that frame? Is it possible they're 1" ISO cups (30.2mm)? I wonder if it'd be possible to use 1" JIS cups in the frame with the original Raleigh threaded race to use with what I presume is a 26 TPI steer tube on your fork. Interchangeability may take some trial an error (to find a cup that'd work with your threaded race, but it may be an option if you're not comfortable pressing those in.

https://www.sheldonbrown.com/cribsheet-headsets.html

redshift1

To give you some comparison figures, I fitted my ( aluminium ) headset cups to my "531 Pro" steel framed bike ( 1 inch threaded steerer of course ) a couple of months ago. My interference figures were 0.18 mm on one cup and 0.13 mm on the other. I greased the fitted surfaces and used proper bike tools ( press, etc. ) and found the level of force to be "quite high but appropriate". ( I have fitted lots of races, bearings, etc. over the years to various things ).

My gut feeling is that 0.30 mm interference is too high. That's around double and approaching triple my figures. My guess is that you won't even get them in without heavy banging.

I would observe Park Tools recommendation of 0.20 mm maximum interference, particularly if you value that frame.

If you can't find different parts ( as suggested above ), personally I would be inclined to attempt to reduce the cup diameters rather than expand the frame diameters. ( Don't forget to grease or oil the fitted surfaces when you are ready to instal. )

Road Fan

I have measured my cups and they measure a little more than 30.2 mm. The head tube after a light reamer cut measures 29.98 mm as close as I can read it with a digital caliper. The threads are in fact 26 TPI (measured with thread pitch gauges). But the pressed cups do not interface with the threaded steer tube or with the threaded cup, so the 26 versus 24 tpi point does not matter. The only compatibility issue is the diameter of the ball tracks on the crown race, upper and lower pressed cups, and on the threaded race.

Road Fan

Thanks, Andy, I'll take that encouragement and try pressing them in and see what they do. The braze seam is clearly brass, I can see it where I reamed. I only have one cutter, but I can run it a littlle more and make sure it really turns freely. It's a Bicycle Research which I bought on Ebay, but only one cutter. Luckily it is sharp and not worn.

Andrew R Stewart 

The vast majority of 26tpi headsets that I've worked on have significantly different ball track contours (bearing load angle) then most all other headsets do. I also don't suggest mixing tpis between the steerer and the headset parts. Andy

70sSanO

The damage may have already been done, but...

https://www.ebay.com/itm/313798665987

John

Road Fan

Well, I'm not going to bang anything, because I have a press which can generate pretty high pressure. I share your gut feel regarding the degree of interference.

Road Fan

Well, I'm not sure where this is coming from, I never said I intended to mix threads. I DEFINITELY know better than that. but only the top threaded cup "cares" what the thread is. The upper and lower fixed cups do not have any threads, therefore they will never touch the steer tube threads, therefore there is no concern about thread mismatch. I'm pretty sure the threaded cup that I plan to use is the original one, and it matches the thread of the steer tube, which is actually 26 tpi.

I agree with you about the ball tracks. Some of the parts I have around seem to form an angular contact bearing, and some of them seem to be intended to create an axial bearing. I recall the Brit parts, when I dismantled the headset, were more on the axial side. With the axial types, it looks like it's possible to mismatch the bearing track radius (the racetrack the balls will run in). I assume I could test this with a binch of balls and see if I have pairs which match - Sheesh why didn't I mark my parts better???

Andrew R Stewart 

My point was about mixing headset parts to "fix" one issue (press fit in head tube, but retain the threaded upper race to not harm the threading and that the ball tracks (assuming the 26tpi race is like most all I have seen and are of the more axial bearing contact angle) wouldn't match (assuming that the now "new" upper cup was of the more angular contact type).

The shop where I began to learn my chops was a major (for our 1970s market) Raleigh dealer. I learned to hate those axial contact Raleigh headsets so common on Sports, Sprites and Records. We learned that the lower stack took one more bearing than the upper did and you wanted barely more than one ball gap when assembling. We also found that subbing a more common angular contact lower stack cured a lot of the headset adjusting challenges (it binds one way but is loose 180* in the other way...). I remember we came across a special of an Asian made headset with angular contact bearings in 26tpi and a stack height that worked for all those English made Raleighs, my boss bought a lot of these

JohnDThompson 

The first thing I'd do is check the murky depths of the parts cleaner to see if there are more cups that might be the original ones from that frame.

Failing that, a 30.0mm ID head tube can easily be reamed to accept a 30.2mm ISO spec headset, although you'll likely want to have a bike shop do the work. Before doing this, make sure that the threaded parts will work on the fork; Raleigh used non-standard 26tpi thread on some models, rather than 24tpi.

Road Fan

Well, it's done, and it feels good, turns well, is smooth, and there is no sign of the head tube being stressed. Another two years?

I just started pressing in the parts after greasing so they were secure in the head tube and the crown race, added new Park grease, poked new 5/32" balls into heir clean resitng places with more new Park grease, and gently tightened the top nut and the top race. It still needs final adjustment, but I like to wait for a ride or two for that. Now I have to lace up wheels with Al rims, new Pasela Protek tires, give the Alloy AW hub an adjustment, and move on to the brakes and cockpit. The first ride is near, 70 years after it was born!

I also bought a NOS set of bearing parts, for good measure.