Bicycle Mechanics - Machinist to modify frame,internal to standard headset

I am a machinist and was wondering if there would be any issues with machining a 3/8"(or whatever fits the frame) aluminum disc to modify an internal or integrated headset frame to a standard headset. Basically I would make a disc to press fit into the frame with a hole size that would allow press fit of a regular headset. I've heard this mentioned but never heard of anyone trying it. Any thoughts or obvious problems I am missing?
Thanks.

Why do it?

I'm thinking of the potential of failure when adding a possibly weak link to a key component at the front of the bike. Unless you have very good reasons to do so, which I'm hoping you'd share, I'd always be concerned when riding with a new relatively untested fabrication at the headset, stem, handlebars, fork etc.

Interesting concept. If I understand your proposal, you want to machine adapters with the outside contours shaped to fit the bearing seats of an integrated headset headtube and with interior holes of the proper diameter for standard press fit headset cups. Right?

If you choose a reasonable strong Al alloy, I don't see why it wouldn't work. You should probably use one of the high strength Lock-Tite bearing and sleeve adhesives to keep them in place.

I basically just need a new frame. I just finished building up an older bike frame(~6 years old) with all new parts and then started noticing a crack in the frame. I've heard bad things about having extra fork movement and wear on integrated headset frames. One of the new frames I am considering is integrated and I have a nice brand new cane creek s6 I'd like to use no matter what frame I get.
Hillrider, you are correct. That is exactly what I am proposing but at the same time, I am a little worried about making myself the guinea pig to this experiment even though I see no reason not to do it.

"I am a little worried about making myself the guinea pig to this experiment"

That's another reason not to. You should be enjoying your riding, not wondering when that frame may/will fail. You have a good basic idea, but the potential for failure remains.

I know I know. lol
But I do alot of design in my work and am a machinist so it's in my nature. From a design point of view, I can't see it putting any more stress on the headtube than any other headset, adapter or regular internal headset. I wouldn't be changing geometry, focus of stress etc etc. But it is a moot point now anyway becasue I already bought a frame with standard headset. Woohoo!!!

Thanks for the replies and imparting good judgement. :)

I get the feeling nodnerb, you will not rest until you design a fork you can hold with your teeth :)

Good luck and be safe!

wow, this reminds me of race kitted Ducati motorcycles with non-concentric spacers in the head tube. By changing the spacer, you can change the steering angle...hehe

"I am a little worried about making myself the guinea pig to this experiment"

That's another reason not to. You should be enjoying your riding, not wondering when that frame may/will fail. You have a good basic idea, but the potential for failure remains.
Try this next time. It works so much better than lame copy / pastinghttp://img203.exs.cx/img203/91/arrowtoreplywquote6it.jpg

Personally the way I would approach this is to sleeve the entire head-tube down to fit a standard headset. So get a standard headtube with 30.2mm ID that accepts standard threaded 1" headsets. Then bore out the inside of the frame's headtube to fit the OD of the new headtube sleeve, with maybe a 0.002" interference fit. Press in with some epoxy, face with headtube facer/reamer and that's it! :)

"Try this next time. It works so much better than lame copy / pasting"

Thanks for bringing this to my attention. For someone who has been using the internet since 1989 in some form or another, I certainly have to get up to speed quick on the latest functionality. So much to learn, it is overwhelming!


And since you prefer ...



Try this next time. It works so much better than lame copy / pasting

Thanks for bringing this to my attention. For someone who has been using the internet since 1989 in some form or another, I certainly have to get up to speed on the latest functionality. So much to learn, it is overwhelming!

Curious....Is it really necessary to place a chemical bonding agent between 2 finished surfaces of a properly sized interference fit? :)

Is boring out the headtube to accept a 1" threaded headtube really possible? re: walls get too thin or ID too large to begin with :eek:

The top and bottom of the integrated headtube is larger in ID (and OD) to accept the bearing race. This larger ID may become unsupported if a constant diameter "plug" is inserted. Will this become a structural issue? or should it be filled w epoxy, which will keep dirt out too :D

its all in good cheer

Pax

Curious....Is it really necessary to place a chemical bonding agent between 2 finished surfaces of a properly sized interference fit? :)I've had a lot of issues with sleeving cylinders with new liners in auto engines. Adjusting interference so that there's still clamping pressure at operating-temps didn't help; no difference between zero interference and tight interference at operating temp. The problem we found was due to two layers taking a load in series, like two springs on top of each other. Each layer ends up talking the full load itself and you end up with weaker strength from two thin layers. Two springs on top of each other is softer than one single one of the same height. Two thin layers of wood, like plywood, doesn't offer the same stiffness as a single solid piece of wood.

So structurally, if you can bond them together tightly, they don't function in series any more. Limiting the sliding between layers, no matter how miniscule leads to both layers taking the load in parallel instead.



Is boring out the headtube to accept a 1" threaded headtube really possible? re: walls get too thin or ID too large to begin with :eek:
I'm assuming that it's an alloy frame that's being converted. Most of the integrated headsets I've seen have been installed on thickwalled alloy frames and boring those out 1mm on the ID isn't going to be difficult. Or even if you sleeve down an intergrated headset for 1-1/8" fork and use a 1" fork with 1" standard headset, that's definitely not going to reduce wall-thickness by any.



The top and bottom of the integrated headtube is larger in ID (and OD) to accept the bearing race. This larger ID may become unsupported if a constant diameter "plug" is inserted. Will this become a structural issue? or should it be filled w epoxy, which will keep dirt out too :D
Yeah, I was thinking of milling off ALL of the ridges for the integrated headset parts so it's completely smooth on the inside. Then sleeve it to accept a 1" or 1-1/8" standard headset. The contact area will be on the entire surface area of the headtube and new sleeve. If you make the sleeve with a T-flange on the bottom, then there's no issue of any sliding of the sleeve either.

Danno, very well though out! interesting to see that sleeving stuff under axial load have the same "in series" issues as a bending beam.

The flange idea is also really cool. Still a little sceptical about being able to bore things out properly... plus you may have to take a finishing cut on the plug (who knows what the surface finish is like...eek)

Looking at the cyclic loading on the head tube, yeah, any loading and unloading in any direction is going to try to work things loose

Cheers!