This is for those who have first hand experience of Chris King headsets, so please no hearsay or conjecture.
Have you had the headset scoring the fork steerer tube?
Did you have the headtube faced before installation?
Did this occur on a steel or aluminium steerer?

I’ve got 4 bikes with Chris King Headsets and never seen an issue with scoring. One of the steerers is a carbon one too. None are what you’d call long travel either.

yes
yes
aluminium steerer, 160mm forks

never happened with 100mm or 130mm forks though and those 160mm forks are fairly heavily ridden

Never had it happen to me. Same CK headset on a Reba (ali steerer) and a Thor (again ali steerer). Headsets been used on 3 bikes, and never faced any of the headtubes.

Don’t doubt it happens, don’t know whether I’m convinced that it’s a failure of King’s design though.

Yes
Yes
Aluminium Pikes 140mm

Yes, yes , aluminium steerer on several forks , mainly 100mm travel Rockshox. Saw this happen regularly back when i was a shop mechanic.

It’s never happened to me on 130mm forks on XC bike or 200mm triples on freeride bike (same headset). I don’t know if it’s happened to my jump bike but my handlebars haven’t snapped off yet, so that’s OK.

Yes. Yes. Alu.

Yes on both my bikes, Turner 5 spot with Pikes & Chromag Samurai with Pikes.
Yes they were both faced.
Aluminium steerers on both (Pike 454 u-turn) Don’t really run them above 130mm, only very occasionally are they wound out to the full 140mm.

Now ditched the Kings on both bikes and running Cane Creek S8s with no problems whatsoever.

happened to me too – quite badly on a set of RC40 Fighters and starting on a set of Marz AMSLs before I got rid of it

Yes, Yes, Alu 150mm

Yes, Yes, Alu 130mm

Yes
No
Alu 150mm

I have 3 CK headsets and none of them have scored the steerer, 2 of the bikes have had the headtube faced the other not. All steerers alu.

Yes, Yes, Alu 140mm

Yes, Yes, Alu 130mm

Won’t run a king on more than 100mm travel now.

No
No

One is a cotic with 130mm revelations

The other is a whyte with 150 mm Mavericks, which I guess is a safe bet, seeing as they don’t have a steerer as such to start with….

Used CK with:

Reba’s 115mm
Pace RC-31’s
Marzocchi Bombers 115mm

on 3 differeent frames, never face, no scoring

Seen a few in the workshop. All with longer travel forks. Not seen any really deep scoring, but once it happens it means the top race of the headset stays ‘loose’. Wouldn’t use one myself, the original Ahead design is much better.

yes
yes
on my magura durin and sids 100mm
seen it on longer travel forks also

Faced frame
160mm forks
3 years, no scoring, but then I’ve always been careful to make sure that there is grease between the top race and steerer.

Have you had the headset scoring the fork steerer tube?

Yes

Did you have the headtube faced before installation?

Yes

Did this occur on a steel or aluminium steerer?

Steel

170mm travel

Yes
Yes
Alu

100mm

Is it really a problem? Mine have only ever been lightly scored….

yes
yes

rs pikes alu steerer

Yes and yes.
On both carbon and alu steerer tubes.

It’s never been an issue, the scoring isn’t bad and it’s not affected the headset or fork in any way.

No scoring, used on 3 frames, with travel up to 160mm.

However, I have found yesterday that the inside of the lower cup is heavily scored on the inside on one side. It appears my steerer has scored my King headset!

My LBS, also say they’ve never seen it (are a CK stockist)

Yep i have it, doesn’t bother me in the slightest..Was faced, 150mm alu steerer

And for those unlike tj who can’t see stress colours

If I was really worried about this I’d go out to the garage and strip one of my five (well one belongs to the wife really) CK equipped bikes to check for damage, but its cold out there and I can’t be arsed.
Anyway is that really scoring or just cosmetic marking?

you can barely feel it with your nail

Does the mark line up with the o-ring in the top cap?

yep

Took my Pikes off my hardtail on Sunday and can’t say I notices and scoring.

Can’t see it being an issue if it did. It’s not likely to eventually cut through is it!

I wonder if its due to dirt getting trapped between the o-ring and the steerer and marking the steerer if there’s a small amount of play present, the o-ring itself shouldn’t be hard enough to mark the steerer on its own.

Got a CK, had it in two frames both faced, both fitted with either Reba’s 100mm or Revs 130mm. Both had badly scored tubes.

when my fox forks got scored by the headset it was probably about half a mil deep. I was happy riding them up to a point, but once I realised it was continuing to grow, I binned the headset.

no issues on a carbon road steerer, regular use over 4 years. same fork, same headset, inspected a couple of times and all well and good.

“due to dirt getting trapped between the o-ring and the steerer and marking the steerer if there’s a small amount of play present”

it probably is…

Nope, the marking is normally the whole depth of the race, not just around where the o-ring fits. I’m not sure it will cause detrimental damage to the fork, but if left it definitely stops the headset working properly.

Question is, why would you buy a King when:
-they have been shown to score steerer tubes
-there is a better headset design out there
-they cost 4 times more than a very good headset

not CK, but i had a set of manitou minutes i used in the peaks, those things were so flexible that the sterrers deflection brought it into contact with the cups!

Several bikes all aluminium steerers all 100mm travel all scored all fitted by reputable bike shops, don’t buy them any more and use hope headsets which don’t score the steerer.

Yes
No
Aluminium Pikes

I’m yet to be convinced that this issue actually causes a risk of failure, so far I’ve only ever seen one photo of an alleged CK induced failure.
You’d think with all these people reporting the so called problem, there’d be steerers failing left right and center