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

[KneesUp]

For some reason I was thinking about this on the way home.

The move from 1" to 1 1/8" headsets seemed to happen around the same time as mountain bikes became popular (so more bikes being given a harder time), but that was also when aluminium frames became popular (aluminium not being as strong as steel) And when the 'ahead' set replaced the threaded headset.

Which one of these factors was the driving force for the change? Or was it marketing?

 

[Globalti]

BING BONG!

@Yellow Saddle to the forum please....

 

[Racing roadkill]

Anti crush.

 

[Crackle]

Anti crush.

A relative?

 

[Hugh Manatee]

My steel Saracen had a one and an eighth back in 1990. They mentioned it quite a lot when I was buying it.

I also have a brand new Steve Potts from a few years later that still has a one inch headset. I really must do something with that!

 

[Yellow Saddle]

Anyone who has used 1" steerers and headsets extensively will know about their primary mode of failure - bearing indentation or so-called false brineleling. This is where the front and rear balls in the lower headset bearing fret away and indent the races and the headset becomes notchy to the point where riding straight ahead becomes a problem. With a notched headset the bike always feels like it fishtails or also as if the rear wheel is flat and the rear kinda sways as you pedal.

This type of bearing is unique to headsets because a ball bearing is not the ideal bearing for steering a bicycle that primarily rides straight ahead. The bearing never gets an opportunity to rotate and replenish its grease. The small sideways handlebar movements cause the balls to just move slightly, but never rotate completely. This causes them to push the grease out at the ball/race interface and make them run dry - steel on steel.

In addition, the flexible 1" steerer flexes a lot at the bottom bearing where the unsupported fork exits the head tube. It vibrates forwards and backwards from road shock and loading, forcing the bearings to move fore/aft and against the grain, so to speak. In other words, this movement is against the natural circular movement the bearing makes when the steering is turned. The combination of these two fretting forces causes micro-weld and breaks. The ball welds against the race over a few molecules and the very next bump breaks the weld and so on and so on. This causes dimpling of the races. These dimples are not impact dimples, but fretting erosion dimples.

One inch steerers are just too weak in bending to prevent this type of movement, hence the thicker and stronger 1 1/8th inch steerer. Although 1/8th of an inch more doesn't seem like much, it is a lot more, since tube strength (in flexion) is proportional to the square of the diameter (Pi R Squared and all that). This extra thickness makes it stronger and headsets last much much longer.

The Aheadset is not related to the move to 1 1/8th steerers, but also contributes in its own way. This is because the beaings are loosely seated in the cups and can move when the steerer bends, thus protecting the balls inside.

I very much doubt that mountain biking is the primary contributing factor but the increased strength certainly helped mountain biking.

One inch aluminium steerers were the worst of all evils but in 1 1/8th they are fine.

 

[KneesUp]

Thanks @Yellow Saddle - very interesting.

The 1" steerer had a very long run though, it has to be said. Do you think there would have been a change if most bikes were still made of steel?

 

[Blue Hills]

I have three bikes with 1 inch headsets - don't find them a great problem.

Isn't there a view that the certain degree of lesser stiffness than 1 1/8th can make some bikes more comfortable?

With regard to tourers with 1 inch headsets do you reckon yellow saddle that they can have issues when front panniers are attached?

 

[froze]

I've had dozens of 1 inch headsets on bikes, one of bikes with a 1 inch headset has over 150,000 miles on it, and knew a LOT of people who have had these headsets and never did I see a failure, in fact 1 inch headsets were the most reliable part on a bike as long as they were kept properly lubed which wasn't very frequently. In fact I've never even seen a cheap Walmart 1 inch headset fail if it was properly maintained! Granted the Walmart jobs did require much more frequent adjusting and lubing to keep it that way but they never smashed their bearings, or had bearing indentations, the only way a 1" inch headset would suffer that is due to complete and utter poor adjustment without lube and allowed to run like that for an extended period of time.

 

[hoopdriver]

I've never heard of any disasters with 1" headsets either, and they were certainly around an awful long time.

 

[Blue Hills]

got to say I find them ultra reliable - my first bike had a 1 inch headset - never touched the headset/abused it, even ran it loose for a short period. When I eventually years years later learned something about bike maintenance I opened it up and regreased it. I think a lot of those old steel 1 inch headsets are incredibly tough. I bought a 20 year old frame recently - sorted the headset - while you can feel a slight something when you turn the bars, even afger my best efforts at adjusting and greasing, you can feel a slight something when you rotate the bars with the wheel off the ground, but not actually when riding. I don't think it is anything to worry about and my favourite esteemed doctor bike seems to agree. Surely you would have to abuse a headset something rotten to get the feared "notchiness" where it became a real issue?

 

[Yellow Saddle]

Thanks @Yellow Saddle - very interesting.

The 1" steerer had a very long run though, it has to be said. Do you think there would have been a change if most bikes were still made of steel?

No, steel wasn't the problem, it was the small tubing. Size matters far more than material. Look at the original Cannondale aluminium frames. They were extremely thin, yet stiffer than steel in that particular application. Going from 1" steel to 1 1/8" aluminium make the steerer much stiffer.

 

[Yellow Saddle]

got to say I find them ultra reliable - my first bike had a 1 inch headset - never touched the headset/abused it, even ran it loose for a short period. When I eventually years years later learned something about bike maintenance I opened it up and regreased it. I think a lot of those old steel 1 inch headsets are incredibly tough. I bought a 20 year old frame recently - sorted the headset - while you can feel a slight something when you turn the bars, even afger my best efforts at adjusting and greasing, you can feel a slight something when you rotate the bars with the wheel off the ground, but not actually when riding. I don't think it is anything to worry about and my favourite esteemed doctor bike seems to agree. Surely you would have to abuse a headset something rotten to get the feared "notchiness" where it became a real issue?

Yes they are reliable but your anecdotal findings can't reverse the fact that headsets don't last on 1" steerers. Regreasing is not the problem, it is the fact that the balls don't rotate and just a little bit of riding removes all the grease between ball and race and it then welds. This in spite of plenty of grease in the headset. If you could rotate the steering every few minutes, that would solve the problem but as you can imagine, that's not possible.

You don't have to abuse a headset to make it notchy. You just have to use it normally and perfectly as intended.

 

[Racing roadkill]

I never had a problem with my 1" headsets, I've got a range of different dimensioned headsets now, with both straight and tapered steerers, but none of them came with 1". 1 - 1 1/8 and 1 - 1 1/2 tapered seem to be a popular choice with frame / bike builders of late. My 520 is a 1 1/8 straight.

 

[Blue Hills]

I'm not sure what you really mean by "anectodal" yellow saddle. It's 20 years of real life experience, treating one pretty poorly. Or are you saying that my "anectodal" experience has been somehow blessed?