Fork crown too small for headset?!
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Fork crown too small for headset?!
I was planning on swapping my unbranded carbon fork for an unbranded steel fork to make my bike "tougher" for commuting, as well as possibly adding racks and full fenders without having to do annoying DIY work-arounds in the near future.
I haven't swapped the crown race yet, but even just by putting the steel fork into the headtube (both 1 1/8" threadless), it looks like the crown of the fork is too small for the headset!
On my carbon fork, the headset would have a "perfect fit" and sit on the crown nicely.
On this steel fork, the crown of the fork is basically "in" the headset, with ~4mm of the headset "hanging over" the crown of the fork.
EDIT: Oh I forgot to mention it's a Cane Creek Solos headset. The carbon fork's steer tube is not tapered.
The frame is a Kona JTS, approx 2007-8.
Does this mean I can't use the steel fork on my bike? I thought I could basically swap any 1 1/8" threadless fork with another!
I haven't swapped the crown race yet, but even just by putting the steel fork into the headtube (both 1 1/8" threadless), it looks like the crown of the fork is too small for the headset!
On my carbon fork, the headset would have a "perfect fit" and sit on the crown nicely.
On this steel fork, the crown of the fork is basically "in" the headset, with ~4mm of the headset "hanging over" the crown of the fork.
EDIT: Oh I forgot to mention it's a Cane Creek Solos headset. The carbon fork's steer tube is not tapered.
The frame is a Kona JTS, approx 2007-8.
Does this mean I can't use the steel fork on my bike? I thought I could basically swap any 1 1/8" threadless fork with another!
Last edited by Dan515; 03-21-13 at 02:20 PM.
#2
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Does your carbon fork have a tapered steerer tube????
That would make your straight steel steerer too small to fit the lower bearing assy without adaptors.
That would make your straight steel steerer too small to fit the lower bearing assy without adaptors.
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I'm guessing this is a zero stack headset and head tube.
They look great with a beefy carbon fork sitting flush against them, but all kinds of wrong with a more traditional fork hanging out... but I bet the 1 1/8" crown race is the same on both forks, like the first two in the diagram.
Also, the carbon fork is likely a lot stronger than the steel fork, impact resistance aside.
They look great with a beefy carbon fork sitting flush against them, but all kinds of wrong with a more traditional fork hanging out... but I bet the 1 1/8" crown race is the same on both forks, like the first two in the diagram.
Also, the carbon fork is likely a lot stronger than the steel fork, impact resistance aside.
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Last edited by Kimmo; 03-21-13 at 01:59 PM.
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Many forks, particularly carbon, have a rather wide crown race seat and the crown race will either be completely inside the seat or flush with the edges. I expect your steel fork has a smaller crown race seat and the race hangs over the edges by a bit. Not a problem and, in fact, an advantage since removing the crown race in the future will be a lot easier.
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I'm guessing this is a zero stack headset and head tube.
They look great with a beefy carbon fork sitting flush against them, but all kinds of wrong with a more traditional fork hanging out... but I bet the 1 1/8" crown race is the same on both forks, like the first two in the diagram.
Also, the carbon fork is likely a lot stronger than the steel fork, impact resistance aside.
They look great with a beefy carbon fork sitting flush against them, but all kinds of wrong with a more traditional fork hanging out... but I bet the 1 1/8" crown race is the same on both forks, like the first two in the diagram.
Also, the carbon fork is likely a lot stronger than the steel fork, impact resistance aside.
As for the reason for swapping forks - I'm worried about the impact resistance since I've got lots of dings on my bike from other commuters locking up next to me, and I'd rather have a dinged up steel fork than a cracked carbon one. Plus, I figure having a steel fork will make my bike less attractive to thieves. I also want hassle-free rack and fender installation in the near future.
Many forks, particularly carbon, have a rather wide crown race seat and the crown race will either be completely inside the seat or flush with the edges. I expect your steel fork has a smaller crown race seat and the race hangs over the edges by a bit. Not a problem and, in fact, an advantage since removing the crown race in the future will be a lot easier.
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There should be a plastic cover bridging the gap between the crown race and cup.
Wow, those pics must be super crappy... we pretty much just need a silhouette.
Wow, those pics must be super crappy... we pretty much just need a silhouette.
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Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
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Okay so here's the best picture I can provide:
This is without any crown race (I haven't managed to get the crown race off of the carbon fork yet...). You can see that there's a small gap between the inner lip of the headset and the crown/crown seat area (not sure of the terminology) of the fork. On my unbranded carbon fork, the bottom of the headset sits flush with the fork crown, whereas here it's "hanging over" the steel fork.
This is without any crown race (I haven't managed to get the crown race off of the carbon fork yet...). You can see that there's a small gap between the inner lip of the headset and the crown/crown seat area (not sure of the terminology) of the fork. On my unbranded carbon fork, the bottom of the headset sits flush with the fork crown, whereas here it's "hanging over" the steel fork.
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Okay so here's the best picture I can provide:
This is without any crown race (I haven't managed to get the crown race off of the carbon fork yet...). You can see that there's a small gap between the inner lip of the headset and the crown/crown seat area (not sure of the terminology) of the fork. On my unbranded carbon fork, the bottom of the headset sits flush with the fork crown, whereas here it's "hanging over" the steel fork.
This is without any crown race (I haven't managed to get the crown race off of the carbon fork yet...). You can see that there's a small gap between the inner lip of the headset and the crown/crown seat area (not sure of the terminology) of the fork. On my unbranded carbon fork, the bottom of the headset sits flush with the fork crown, whereas here it's "hanging over" the steel fork.
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If I'm reading you correctly, the issue is that the crown race is overhanging the crown front and back.
If that's the issue, there isn't one.
Historically steel fork crowns were made narrow enough for the races to overhang. This made it easier to knock them off with a U-shaped tool. This is the way things were for almost a century. Over the last few decades, crowns got larger, first to accommodate suspension forks, and later carbon forks, rendering the tools that push them out from below obsolete.
All that matters is that the crown seat diameter is adequate to make a press fit except for the split crown centering cones used with some cartridge bearing headsets.
If that's the issue, there isn't one.
Historically steel fork crowns were made narrow enough for the races to overhang. This made it easier to knock them off with a U-shaped tool. This is the way things were for almost a century. Over the last few decades, crowns got larger, first to accommodate suspension forks, and later carbon forks, rendering the tools that push them out from below obsolete.
All that matters is that the crown seat diameter is adequate to make a press fit except for the split crown centering cones used with some cartridge bearing headsets.
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