drilling out head tube from 1" to 1 1/8"?
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Originally Posted by pnj
I don't care what the QBP catalog says. I know kids have done this.
king, fsa, dia-compe all make 1 1/8 headsets that fit both mtn. bike and bmx frames. the exact same headsets....same size head tubes, same size stear tubes. you know, that's why you can run a mtn. bike stem on a bmx fork.
king, fsa, dia-compe all make 1 1/8 headsets that fit both mtn. bike and bmx frames. the exact same headsets....same size head tubes, same size stear tubes. you know, that's why you can run a mtn. bike stem on a bmx fork.
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Originally Posted by pnj
I know it's been done because in the bmx world, it took some time before all frames had 'oversized' headtubes. kids had old 1 inch frames but bought newwer 'oversized' (1 1/8) forks.
I don't know how they did it, I just know it involved using loose ball bearings. as in, no bearing retainer.
I don't know how they did it, I just know it involved using loose ball bearings. as in, no bearing retainer.
There's a chart of relevant headset dimensions at the
"Headset" entry of my online Bicycle Glossary - https://sheldonbrown.com/gloss_ha-i.html#headset
Sheldon "No Way" Brown
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Oh, but think of the weight savings! You'll just fly without that extra head tube weight!
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Originally Posted by Aussomeman
the situation is like this: i'm running my current mtb as a rigid singlespeed (with tensioner). it's an older aluminum frame with a 1 1/8" head tube, and i'm running a rigid threadless steel fork with it. i'm looking to pick up an old steel frame with horizontal drops so i can drop the tensioner and build the aluminum frame back up with some gears. i also just picked up a sweet old school white brothers fork with a 1 1/8" steerer that i'm planning to install on the aluminum frame, and the steel frame i'm looking at buying right now has a 1" head tube and no fork included. I was hoping perhaps i could just swap the fork from my current rig onto the steel frame, but if it's that sketchy, i'll probably just look for a 1" fork.
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Is it possible to drill out a 1" head tube to enable the use of a 1 1/8" headset and fork, or would the structural integrity of the frame be compromised? I'm looking at purchasing a rigid steel frame with a 1" head tube for a singlespeed project, and I'd like to be able to use the fork(s) I've already got (both are 1 1/8) with it. I could swear I read that this was possible online somewhere. I thought it was at Sheldon Brown's site, but I can't seem to find it again. Thanks in advance!
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What brings you here @dcalkin?
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IME, a 1 1/8” steerer can pass through an 1” head tube.
I’ve made adapters that fit on the outside of the steerer tube to allow the installation of 1/18” headset cups ”outboard” of the original bearing mount.
it does change the geometry somewhat, but is generally manageable.
I’ve made adapters that fit on the outside of the steerer tube to allow the installation of 1/18” headset cups ”outboard” of the original bearing mount.
it does change the geometry somewhat, but is generally manageable.
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IME, a 1 1/8” steerer can pass through an 1” head tube.
I’ve made adapters that fit on the outside of the steerer tube to allow the installation of 1/18” headset cups ”outboard” of the original bearing mount.
it does change the geometry somewhat, but is generally manageable.
I’ve made adapters that fit on the outside of the steerer tube to allow the installation of 1/18” headset cups ”outboard” of the original bearing mount.
it does change the geometry somewhat, but is generally manageable.
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Although this is a 15yo thread resurrection, I've wondered why it wouldn't be possible to make head cups that would fit the outside of the steerer tube. My guess has been that there is too much irregularity in the roundness of the material after welding and not always enough space for a safe install. I've often thought in a worse case scenario it might be useful to save a frame.
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thanks for all the replies, folks - didn't realize this would be such a hot topic. i kinda figured it wasn't too practical, but the situation is like this: i'm running my current mtb as a rigid singlespeed (with tensioner). it's an older aluminum frame with a 1 1/8" head tube, and i'm running a rigid threadless steel fork with it. i'm looking to pick up an old steel frame with horizontal drops so i can drop the tensioner and build the aluminum frame back up with some gears. i also just picked up a sweet old school white brothers fork with a 1 1/8" steerer that i'm planning to install on the aluminum frame, and the steel frame i'm looking at buying right now has a 1" head tube and no fork included. I was hoping perhaps i could just swap the fork from my current rig onto the steel frame, but if it's that sketchy, i'll probably just look for a 1" fork.
You can buy a brand new 1" steel fork, threaded or threadless for less than $100 new (more like $75) and used ones are common and inexpensive on eBay - If there's a vintage crown you're looking for, chrome, painted, whatever you want you'll find it fairly quickly. If you want a beautiful, light, top tier all carbon 1" threadless fork, you can get one for about $275 (columbus minimal) or something like Wound Up for different style points (but $$)
And all prices in between. So it's probably not worth a lot of time and effort to try to get by with what you have?
Last edited by Camilo; 02-28-21 at 04:17 PM.
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You can buy a brand new 1" steel fork, threaded or threadless for less than $100 new (more like $75) and used ones are common and inexpensive on eBay. If you want a beautiful, light, top tier all carbon 1" threadless fork, you can get one for about $275 (columbus minimal)
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You really think Aussomeman hasn't figured something out in the last 15 years since they asked?
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#46
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Well, as long as you're all here...
Being faced with a similar problem, I'm curious whether anyone might have some feedback/wisdom to share (acerbic or otherwise) regarding the one potential solution that seems rather obvious to me, but that I've yet to see anyone mention in this or any other thread on this topic.
If I have a carbon fork with 1-1/8" aluminum steerer that I'd like to install in a carbon fiber frame that was designed for a 1" steerer fork, is there any reason why the aluminum steerer couldn't be turned down on a lathe to the 1" ISO spec? IOW, take the shaft from 28.6mm to 25.4mm, and the crown race seat from 30.1mm to 26.4" ?
Seems to me that taking roughly 2mm - 2.5mm off of the meat of the steerer shaft should still leave it well within the safety margin in terms of durability (though i don't have the specific fork in hand yet, so can't measure the ID of the shaft to be sure of the resultant wall thickness.) Obviously this would need to be done by a competent shop, with an eye kept on avoiding overheating of the shaft and affecting the aluminum/carbon bond. And careful attention to the surfaces and radius of the race seat and crown face.
Any other reasons to avoid this approach? (I understand that it's easier/simpler/cheaper to buy an appropriate fork, but in this case I'm highly motivated to use this particular fork if I can find any way to make it work. It's a 650c aero fork, not easy to source. I may fab some external adapters for 1-1/8" cups as a plan B if turning down the steerer is not a worthwhile approach. Unless anyone knows of a source for such adapters?
Many thanks for any thoughts/jeers/flames/musings/tributes to forebearers, etc.
If I have a carbon fork with 1-1/8" aluminum steerer that I'd like to install in a carbon fiber frame that was designed for a 1" steerer fork, is there any reason why the aluminum steerer couldn't be turned down on a lathe to the 1" ISO spec? IOW, take the shaft from 28.6mm to 25.4mm, and the crown race seat from 30.1mm to 26.4" ?
Seems to me that taking roughly 2mm - 2.5mm off of the meat of the steerer shaft should still leave it well within the safety margin in terms of durability (though i don't have the specific fork in hand yet, so can't measure the ID of the shaft to be sure of the resultant wall thickness.) Obviously this would need to be done by a competent shop, with an eye kept on avoiding overheating of the shaft and affecting the aluminum/carbon bond. And careful attention to the surfaces and radius of the race seat and crown face.
Any other reasons to avoid this approach? (I understand that it's easier/simpler/cheaper to buy an appropriate fork, but in this case I'm highly motivated to use this particular fork if I can find any way to make it work. It's a 650c aero fork, not easy to source. I may fab some external adapters for 1-1/8" cups as a plan B if turning down the steerer is not a worthwhile approach. Unless anyone knows of a source for such adapters?
Many thanks for any thoughts/jeers/flames/musings/tributes to forebearers, etc.
Last edited by Redshift96; 07-25-21 at 06:51 PM.
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Being faced with a similar problem, I'm curious whether anyone might have some feedback/wisdom to share (acerbic or otherwise) regarding the one potential solution that seems rather obvious to me, but that I've yet to see anyone mention in this or any other thread on this topic.
If I have a carbon fork with 1-1/8" aluminum steerer that I'd like to install in a carbon fiber frame that was designed for a 1" steerer fork, is there any reason why the aluminum steerer couldn't be turned down on a lathe to the 1" ISO spec? IOW, take the shaft from 28.6mm to 25.4mm, and the crown race seat from 30.1mm to 26.4" ?
Seems to me that taking roughly 2mm - 2.5mm off of the meat of the steerer shaft should still leave it well within the safety margin in terms of durability (though i don't have the specific fork in hand yet, so can't measure the ID of the shaft to be sure of the resultant wall thickness.) Obviously this would need to be done by a competent shop, with an eye kept on avoiding overheating of the shaft and affecting the aluminum/carbon bond. And careful attention to the surfaces and radius of the race seat and crown face.
Any other reasons to avoid this approach? (I understand that it's easier/simpler/cheaper to buy an appropriate fork, but in this case I'm highly motivated to use this particular fork if I can find any way to make it work. It's a 650c aero fork, not easy to source. I may fab some external adapters for 1-1/8" cups as a plan B if turning down the steerer is not a worthwhile approach. Unless anyone knows of a source for such adapters?
Many thanks for any thoughts/jeers/flames/musings/tributes to forebearers, etc.
If I have a carbon fork with 1-1/8" aluminum steerer that I'd like to install in a carbon fiber frame that was designed for a 1" steerer fork, is there any reason why the aluminum steerer couldn't be turned down on a lathe to the 1" ISO spec? IOW, take the shaft from 28.6mm to 25.4mm, and the crown race seat from 30.1mm to 26.4" ?
Seems to me that taking roughly 2mm - 2.5mm off of the meat of the steerer shaft should still leave it well within the safety margin in terms of durability (though i don't have the specific fork in hand yet, so can't measure the ID of the shaft to be sure of the resultant wall thickness.) Obviously this would need to be done by a competent shop, with an eye kept on avoiding overheating of the shaft and affecting the aluminum/carbon bond. And careful attention to the surfaces and radius of the race seat and crown face.
Any other reasons to avoid this approach? (I understand that it's easier/simpler/cheaper to buy an appropriate fork, but in this case I'm highly motivated to use this particular fork if I can find any way to make it work. It's a 650c aero fork, not easy to source. I may fab some external adapters for 1-1/8" cups as a plan B if turning down the steerer is not a worthwhile approach. Unless anyone knows of a source for such adapters?
Many thanks for any thoughts/jeers/flames/musings/tributes to forebearers, etc.
#48
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Seems to me that taking roughly 2mm - 2.5mm off of the meat of the steerer shaft should still leave it well within the safety margin in terms of durability (though i don't have the specific fork in hand yet, so can't measure the ID of the shaft to be sure of the resultant wall thickness.) Obviously this would need to be done by a competent shop, with an eye kept on avoiding overheating of the shaft and affecting the aluminum/carbon bond. And careful attention to the surfaces and radius of the race seat and crown face.
Any other reasons to avoid this approach? (I understand that it's easier/simpler/cheaper to buy an appropriate fork, but in this case I'm highly motivated to use this particular fork if I can find any way to make it work.
Any other reasons to avoid this approach? (I understand that it's easier/simpler/cheaper to buy an appropriate fork, but in this case I'm highly motivated to use this particular fork if I can find any way to make it work.
IME, a 1 1/8” steerer can pass through an 1” head tube.
I’ve made adapters that fit on the outside of the steerer tube to allow the installation of 1/18” headset cups ”outboard” of the original bearing mount.
it does change the geometry somewhat, but is generally manageable.
I’ve made adapters that fit on the outside of the steerer tube to allow the installation of 1/18” headset cups ”outboard” of the original bearing mount.
it does change the geometry somewhat, but is generally manageable.
Now, one possibility would be to sleeve it. I.E. Find a tight fitting carbon fiber or aluminum tube, epoxy in place, and machine down as you desire. Make sure the tube extends far enough down to be pinned with the brake caliper.
As @dabac suggested, the 1 1/8" fork may barely fit inside the 1" head tube. So if you made custom 1 1/8" bearing seats, it may work.
I'm wondering if some of the BMX kids making the conversion mentioned earlier simply added upper and lower thrust bearings, inserted the fork greased the tube.
My preference, however, would be to hunt down the correct part.
Kestrel 1" fork:
https://www.ebay.com/itm/402902625039
Profile Designs 1" fork:
https://www.ebay.com/itm/164781471339
Or, even get a steel fork made to your specs.
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Seems to me that taking roughly 2mm - 2.5mm off of the meat of the steerer shaft should still leave it well within the safety margin in terms of durability (though i don't have the specific fork in hand yet, so can't measure the ID of the shaft to be sure of the resultant wall thickness.) Obviously this would need to be done by a competent shop, with an eye kept on avoiding overheating of the shaft and affecting the aluminum/carbon bond. And careful attention to the surfaces and radius of the race seat and crown face.
As a total flyer, and this is pretty far out there, it may be possible to sleeve the ID with a machined Cro-Moly tube to maintain the same structural integrity. Probably have to machine the ID to be close to a press fit with the sleeve. Then machine the OD of the steerer. You’ll need an engineer to give you the material type and dimensions.
Adequately bonding the sleeve has it’s own problems. I’m not sure what can be used. I don’t think it can just be press fit since there would probably be an issue with heating the aluminum steerer and the carbon. Plus trying to press fit that length could be problematic.
John