Why did headsets change from 1"to 1 1/8"?

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SkipdiverJohn

Deplorable Brexiteer
Location
London
1 1/8" threaded seemed to be more popular on MTB's than it ever was on Road frames. Just remembered I've actually got two, not one, Raleigh MTB frames with 1 1/8" headsets, both 1991. If you look at the old Raleigh catalogues from that period, its clear that the 1 1/8" was marketed as a better/stronger spec for the top end lugged 501 & 531 frames. The cheaper 18-23 stuff made do with 1" headsets, but IIRC, Raleigh beefed these up by fitting old-school BMX 21.1mm stems into them, not the 22.2 mm you'd expect - so even the smaller 1" headset would have a stronger steerer made of thicker tubing than a Road frame. I recently scrapped a low-end early 90's Huffy MTB, that also had a 1" headset built with a BMX size stem, so it wasn't only Raleigh doing this.
I don't remember, BITD, seeing very many MTB's with bent forks, but bent Road forks weren't unusual; bent backwards towards the down tube if crashed into something solid, or bent forwards if subjected to a heavy landing - usually seen on stripped-down "tracker" bikes with cowhorn bars.
 
Location
Loch side.
Not really.
He says (correctly) that 1 1/8" is better than 1" for headset life and performance, but doesn't seem to actually claim that's why the 1 1/8" size was introduced.
Without going through all the what was and, wasn't said, I'll answer the question directly. A bigger tube can be made stiffer, yet lighter than a smaller tube. I've explained that before, perhaps in different contexts but whether we talk crank spindles or steerers, the concept is the same.

Further, the advent of large tube aluminium frames (again, using bigger-but-stronger concept) has made it difficult to manufacture the junction between fat downtube and narrow headtube. This fact thus favoured the move to larger steerers. I'm not sure what the primary driver was, but ease of manufacture is always a factor. This trend eventually lead to the tapered headtube, allowing for super fat downtubes without awkward joints at the head tube.

If you ever get the opportunity to take a close look at a Cannondale CAAD 4 frame, look at the head-tube/downtube joint. It is ridiculous. A very big downtube meets a super skinny 1 inch head tube. It even looks awkward, nevermind the factory acrobatics required to make it.
 
Location
Loch side.
I don't remember, BITD, seeing very many MTB's with bent forks, but bent Road forks weren't unusual; bent backwards towards the down tube if crashed into something solid, or bent forwards if subjected to a heavy landing - usually seen on stripped-down "tracker" bikes with cowhorn bars.

Yes, they were common as you said, but note that it was the fork blades that bent, not the steerer. I say this because these bikes were still rideable after the crash. Had the steerer bent, the steering would have seized. 1 inch steerers are beasts. They're made from thick CroMo that's much thicker at the bottom than at the top, being internally swaged.
 
My Pace Research (back in 1990-1995) had a 1" headset
BUT

It was a Shimano 105 item on mine
The top cup was machined out slightly (no lock-nut), & was tightened from under the fork-crown
The stem & steerer tube were one-piece, if you ordered new, they'd weld as you wanted, or the dealer recommended (also available as a spare, for old bike)

It was essentially the precurser to the 'Aheadset', & the present method, but upside down
Oh!!, & a grease nipple too (proper car type), with grease-nipple in the BB shell (cartridge bearings)

Bullseye cranks pre-dated, the present (eg; Shimano) pattern, but were atrocious for staying tight!

Not mine, just for illustration

489772

489773

489774

489775

10mm nut to slacken the steerer
5mm allen bolts to reclamp the blades, which were individually replaceable, or later swap for their own suspension forks
(I never used suspension
489776

In the 6 years (?) I had it, I never had a headset problem
Granted, I probably changed the balls, & kept it well-greased

http://www.goatsurfer.com/pace_forks.html#1989
 
Location
Loch side.
My Pace Research (back in 1990-1995) had a 1" headset
BUT

It was a Shimano 105 item on mine
The top cup was machined out slightly (no lock-nut), & was tightened from under the fork-crown
The stem & steerer tube were one-piece, if you ordered new, they'd weld as you wanted, or the dealer recommended (also available as a spare, for old bike)

It was essentially the precurser to the 'Aheadset', & the present method, but upside down
Oh!!, & a grease nipple too (proper car type), with grease-nipple in the BB shell (cartridge bearings)

Bullseye cranks pre-dated, the present (eg; Shimano) pattern, but were atrocious for staying tight!

Not mine, just for illustration

View attachment 489772

View attachment 489773

View attachment 489774

View attachment 489775

10mm nut to slacken the steerer
5mm allen bolts to reclamp the blades, which were individually replaceable, or later swap for their own suspension forks
(I never used suspension
View attachment 489776

In the 6 years (?) I had it, I never had a headset problem
Granted, I probably changed the balls, & kept it well-greased

http://www.goatsurfer.com/pace_forks.html#1989
Interesting. I've never seen that before.
 

rogerzilla

Legendary Member
Forks should bend easily compared to frames - they are supposed to be sacrificial. I bought a Raleigh Twenty that had been front-ended. The fork was trashed but the frame is perfect. Even the head cup reaming is still spot on.
 

SkipdiverJohn

Deplorable Brexiteer
Location
London
@midlife, do you reckon that bulge in the downtube would coincide with the position of the butting?? Assuming it is a butted frame of course. What is it, Tange or Ishiwata or something? Obviously not Reynolds or Columbus, I'm wondering who made "022" spec forks....
 

overmind

My other bike is a Pinarello
It is only anecdotal, but I recently had a problem with a 1" headset. I found denting in the crown race but the bearings were badly corroded also. I cannot remember if the dents were at front and rear but they may have been (I still have the old crown race, I will take a picture and post).

The headset had been fairly loose and wobbling for a long time. I had not been able to adjust it correctly. It was either a little loose or too tight so I opted for a little loose.

I replaced the crown race, bearings and most of the original headset (but left the cups on the frame as they were ok). Once I had done this I was able to get the adjustment just right (turning easily with no wobble when front-brake applied and rocking forks).

I do not know if anybody has mentioned this but the forks on this particular road bike are very straight (vitesse sprint). 80s/90s racers I had in the past had curved front forks which presumably absorbed shocks better. Could having straight forks (without any suspension) have increased the load on the bearing/crown race surfaces?

(background: it took about 6-7 years of daily commuting on this bike for it to reach this stage).
 
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Smokin Joe

Legendary Member
I do not know if anybody has mentioned this but the forks on this particular road bike are very straight (vitesse sprint). 80s/90s racers I had in the past had curved front forks which presumably absorbed shocks better. Could having straight forks (without any suspension) have increased the load on the bearing/crown race surfaces?
It makes no difference. Straight forks are not actually straight, just that instead of the legs being curved they are angled at the junction of the steerer and fork crown to give the same rake.
 

Ajax Bay

Guru
Location
East Devon
It makes no difference. Straight forks are not actually straight, just that instead of the legs being curved they are angled at the junction of the steerer and fork crown to give the same rake.
This, but this geometry gives the same offset. 'Rake' is the head tube angle (from the vertical eg 73 degrees). The behaviour of a bike's steering is dependent on rake and offset.
Jobst Brandt on 'Rake': https://yarchive.net/bike/rake.html
See attached g
490177


raph of offset v head tube / steerer angle (rake) from Tony Oliver's book 'Touring Bikes'.


View: https://www.amazon.co.uk/Touring-Bikes-Practical-Tony-Oliver/dp/1852233397
 
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andrew_s

Legendary Member
Location
Gloucester
It makes no difference. Straight forks are not actually straight, just that instead of the legs being curved they are angled at the junction of the steerer and fork crown to give the same rake.
As overmind suggested, straight fork blades don't absorb shocks as well as curved blades.

Any load applied will be purely radial between the initial bump contact and the hub.
With a straight-blade fork, the load direction will be more or less straight along the axis of the fork blade, so you will be compressing it rather than bending it.
With a curved blade on the other hand, the same applied load will be at a fair angle to the end of the blade (up to about 40 deg with an old fashioned sharp curve), so there is a reasonable bending moment.

The difference will depend on the shape of the fork curve- forks with an even curve from top to bottom ("banana" forks, which were widely castigated for their lack of comfort when they first started to appear widely) will be much closer to a straight blade than those with a sharp terminal bend.
 
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Ajax Bay

Guru
Location
East Devon
Could having straight forks (without any suspension) have increased the load on the bearing/crown race surfaces?
It makes no difference.
Agree.
As @overmind suggested, straight fork blades don't absorb shocks as well as curved blades.
Any load applied will be purely radial between the initial bump contact and the hub.
With a straight-blade fork, the load direction will be more or less straight along the axis of the fork blade, so you will be compressing it rather than bending it.
With a curved blade on the other hand, the same applied load will be at a fair angle to the end of the blade (up to about 40 deg with an old fashioned sharp curve), so there is a reasonable bending moment.
The difference will depend on the shape of the fork curve- forks with an even curve from top to bottom ("banana" forks, which were widely castigated for their lack of comfort when they first started to appear widely) will be much closer to a straight blade than those with a sharp terminal bend.
Acknowledge off topic (headsets).
@overmind did not suggest that "straight fork blades don't absorb shocks as well as curved blades" they 'wondered whether' etc.
"Any load applied will be purely radial between the initial bump contact and the hub." Yes, and that radial direction is essentially vertical (from the contact patch) - what other direction could it be?
"With a straight-blade fork, the load direction will be more or less straight along the axis of the fork blade, so you will be compressing it rather than bending it." 'More or less': at about + or - 17 degrees: there will be both compression (F*sin73) and 'bending' (F*cos73*fork length).
"With a curved blade on the other hand, the same applied load will be at a fair angle to the end of the blade (up to about 40 deg with an old fashioned sharp curve), so there is a reasonable bending moment." The bending moment is exactly the same (force resolved at right angles to the effective fork angle times the effective fork length.
"The difference [in the shock-absorbing effect of the fork] will depend on the shape of the fork curve . . . "banana" forks . . . will be much closer to a straight blade than those with a sharp terminal bend." Because the fork blade is a rather rigid structure (focusing on the vertical plane here, not lateral), whether it's straight or curved makes minimal difference to the 'shock' it (doesn't) absorb. @andrew_s is right: and extending his assertion, however curved the fork blade shape, the "[shock-absorbing] difference" . . . "will be much be much closer to a straight blade": negligible difference.
 
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