Author Topic: 1" Threaded Forks and 1 1/8" Headtube. Need Headset!!! (Read 18433 times)

moley · « **on:** October 22, 2008, 11:37 PM »

Hi lads,

After putting Wanted Ads and something in the Tech Section I have decided to post here because it might be something you mid schoolers might know about.

I have a mid 90's F+F.

It has 1" threaded Forks and has a Headtube diameter of 34mm.

Normal sized Headtube diameters suitable for 1" threaded forks are 32.7.

BITD these Headtubes were called Oversized. They eventually went on to be the the normal headtube to fit 1 1/8" threadless forks (I think)

Someone in the mid 90's must have made Headsets to fit the large diameter headtubes (34mm Cups) instead of the normal 32.7 cups.

I know this because I have two of these headsets. One is on my '95 Auburn and it is worn and I want to replace it. The other is on my early 90's Haro Group One.

Apart from the cup sizes. The internals of these 2 different cup sized headset (bearings, races, locking washers and Top Nut) are interchangeable. It's just the cup sizes are bigger so they fit the larger headtube.

So to recap. I am after a 1 1/8" sized headset that is threaded for use with 1" forks

or a 1" threaded headset with 34mm Cups NOT the 32.7mm normal sized cups.

Does anyone know where I can buy one of these headsets or have any information that might help me?

Thanks

PS. I hope this makes sense!!

generallee · « **Reply #1 on:** October 23, 2008, 09:35 AM »

Moley - there ws a thread about this a year or so back -
a few of us bought some GT Pro Seies frames with forks from a dodgy dealer in the States. They were 1.1/8" headtubed frames, but with 1" threaded forks. What you have to do is this -
find some HEADSET REDUCER CUPS - these are shims that you tap into your headtube - then you are able to use 1" headsets, but NOT the usual 1" bmx size - believe it or not there is another size diameter of 1" headset - used by a lot of old road bikes - its called something weird with weird measurement sizes in it - but I can remember - 7/3 8th or something bizarre. I think woollyhatshop.com do them , thats where I got mine. Ther reucer cups can be found on the web somehwere, sometimes alos called Minimizer Cups or Shims.
then you can fit them -
try and dig out the old threas about the GT Pro Series headtube problem - think it may have been aditup who started it. Cheers!
steve

pickle · « **Reply #2 on:** October 23, 2008, 09:57 AM »

have a look at the Chris king site that Crooch put up in New school racing yesterday......they've got loads of diferent headsets on there.....i'm sure they do one??

moley · « **Reply #3 on:** October 23, 2008, 11:36 AM »

Thanks lads!!

I've email the Chris Kings website chappy!!

I have found reducers but I can't find one that does 34mm to 32.7mm!!

motomagII · « **Reply #4 on:** October 23, 2008, 01:07 PM »

jees cant remember how thiws goes but ive done it loads times and my memory is shat.basically fit 11/8 headset cups .then used the bearings loose no cages (you will need more bearings than 1 set )then use inch threaded headset everything else and bobs your uncle sorted .ive dont it prob 5 or six times and works treat but unsure on which bearings i used inch or 11/8 ones .
now ive mentioned this someone will help ya out as another member told me how to do it but cant remember who

thecrooch · « **Reply #5 on:** October 23, 2008, 01:22 PM »

Moley

Have a look here they do some conversion kits http://www.aspirevelotech.com/Merchant2/merchant.mvc'screen=CTGY&Category_Code=HSCONVKIT

plus have a look at this more figures than you can shake a stick at:

The cup skirt is the portion of the headset that fits into the head tube.

Standard 1 inch headsets have a cup skirt diameter of 30.2mm.

Old School 1 inch BMX headsets have a cup skirt diameter of 32.8mm.

Here are the complete specifications (all measurements are in millimeters, weight is in grams)

1. Weight(g)
2. Stack Height
3. Lower Stack Height
4. Cup Skirt
5. Head Tube Inner Diameter
6. Base Plate Inner Diameter
7. Fork Crown Inner Diameter

1 2 3 4 5 6 7
1 inch 2Nut™ - Standard 94 37.4 12.9 30.2 30.1 26.4 26.5
1 inch 2Nut™ - BMX 110 39.1 13.7 32.8 32.8 26.4 26.5
1 inch GripNut™ - Standard 93 33 to 38 12.9 30.2 30.1 26.4 26.5
1 inch GripNut™ - BMX 107 34.2 to 39.2 13.7 32.8 32.8 26.4 26.5
1 inch NoThreadset™ - Standard 84 28.0 12.9 30.2 30.1 26.4 26.5
1 inch NoThreadset™ - BMX 99 32.0 13.7 32.8 32.8 26.4 26.5

pickle · « **Reply #6 on:** October 23, 2008, 01:45 PM »

Moley......PM Harris as i'm sure he's done this a few times? or Alex?

moley · « **Reply #7 on:** October 23, 2008, 02:07 PM »

Below is a list of "conventional" headset standard sizing.

One-inch Japanese Industrial Standard (JIS)
Common on many Asian manufactures bicycles, both road and MTB
Fork column outside diameter- 25.4mm (1")
Head cup race OD- 30.0mm
Acceptable head tube ID range- 29.75mm to 29.9mm
Fork crown race ID- 27.0mm
Fork crown seat OD acceptable range- 27.1mm to 27.2mm
Stem diameter at quill- 22.2mm

One-inch "Modern European" Standard
Many road bike and some MTB bikes
Fork column outside diameter- 25.4mm (1-inch)
Head cup race OD-30.2mm
Acceptable head tube ID range- 29.9mm to 30.1mm
Fork crown race ID- 26.4mm
Fork crown seat OD acceptable range- 26.5mm to 26.7mm
Stem diameter at quill- 22.2mm

1-1/8" Oversized
Many MTB bikes, tandems, some road bikes, BMX bikes
Fork column outside diameter- 1-1/8" (28.6mm)
Head race cup OD- 34mm (My Head race cup size)
Acceptable head tube ID range- 33.75mm to 33.9mm
Fork crown race ID- 30.0mm
Fork crown seat OD acceptable range- 30.1mm to 30.2mm
Stem diameter at quill-25.4mm (1 inch)

1-1/4 inch Oversized
Tandems, some MTB bikes
Fork column outside diameter- 1-1/4 inch (31.8mm)
Head cup race OD- 37mm
Acceptable head tube ID range- 36.75mm to 36.9mm
Fork race ID-33mm
Acceptable fork race seat OD- 33.1mm to 33.2mm
Stem size at quill- 1-1/8 inch (28.6mm)

BMX (threaded, now older types) (Normal OS BMX Size)
Fork column OD- 25.4mm (1 inch)
Head cup OD- 32.7mm
Fork race ID- 26.4mm
Stem size at quill 21.15mm (0.866") (This allows use of thick steering column for strength)

thecrooch · « **Reply #8 on:** February 11, 2009, 01:30 PM »

you may have to go the Chris King route... look here www.aspirevelotech.com

moley · « **Reply #9 on:** February 11, 2009, 01:42 PM »

Use a 1 1/8" to 1" reducer and then use a normal headset!!

http://www.billys.co.uk/english/group.php?prod=hsid-reduc-a

I've not used them but but in theory it should work!!

moley · « **Reply #10 on:** February 11, 2009, 02:33 PM »

I think I have read your question wrong!!

You not trying to use 1" threaded forks are you!!

Measure your Head tube internal diameter!!

That will tell what to use!!

Quote from: haro-os-boy on February 11, 2009, 02:07 PM

Frame is a mid school std BMX 1" headtube

I bet it isn't!!

Standard 1" Head tube Internal diameter is around 32mm.

The oversize Midschool Headtube Internal Diameter is around 34mm.

If your standard 1" headset cup nearly fits but are too loose then the Headtube is oversize. This is to allow it to use Threaded 1" forks with an oversized 1" Headset or 1 & 1/8" headsets (I think).

Have you tried 1 & 1/8" headset cups?