[AndrewTO]

Well, it's not drivetrain, or suspension of wheels/tires, so......

My frame is stripped. I'm giving the whole bike an overhaul/cleaning/checking, etc.

I have a CK headset (yay, just like a million other's! ). I just used a vernier to measure my headtube's I.D. I was thinking i'd simply take the frame into an LBS (eegad! did I just say that?!) and have them ream the tube, as per instructions and "doing things right".

The top of the head tube is still perfectly round. (phew) The bottom isn't and i'm not sure if this is good, not good, or what. I've never run into this problem before.

The bottom ranges in it's I.D. from 1.340" (left side to right side) to 1.325" (front to back). For reference the top measures a consistent 1.335".

So? Good? No good? Have it reamed and hope for the best? Not enough to worry about, install it, shut up and ride?

Please edumacate me.

PATIA!

 

[RonSonic]

How sure are you that these are valid measurements of the tube's out of roundness rather than any burr or other mung in there?

This is NOT the direction that a damaged headtube is elongated. So I'm thinking you're okay - 15 thou is not a lot for an aluminum tube that's been welded on and not remachined. Assuming it hasn't been recut, and I'm sure you'd mention if you'd seen tool marks in there.

Ron

 

[GearHead]

It is not uncommon for the head tube to be slightly oval when a headset is not in it. The difference in ovality you are talking about is quite small, the average diameter of the head tube at the bottom is 1.3325" with the ovality being only +/- 0.56%. When the headset is pressed into the head tube the head tube will become round.

However, Chris King recommends that the head tube bore size is 0.1 mm smaller than the nominal specified 33.9 mm bore. Your head tube is 33.84 mm bottom end and 33.91 top end, you can't remove any more material.

 

[airman]

Well, it's not drivetrain, or suspension of wheels/tires, so......

My frame is stripped. I'm giving the whole bike an overhaul/cleaning/checking, etc.

I have a CK headset (yay, just like a million other's! ). I just used a vernier to measure my headtube's I.D. I was thinking i'd simply take the frame into an LBS (eegad! did I just say that?!) and have them ream the tube, as per instructions and "doing things right".

The top of the head tube is still perfectly round. (phew) The bottom isn't and i'm not sure if this is good, not good, or what. I've never run into this problem before.

The bottom ranges in it's I.D. from 1.340" (left side to right side) to 1.325" (front to back). For reference the top measures a consistent 1.335".

So? Good? No good? Have it reamed and hope for the best? Not enough to worry about, install it, shut up and ride?

Please edumacate me.

PATIA!

I'm thinking like Ron, the elongation is in an odd direction. So am I correct that the headset will be too tight one way, too loose the other by 15 thou? Seems the old headset would have shown some signs of trouble? I know that a vernier is not the weapon of choice for bore measurement...

I suggest these steps:

1) Try to install the new headset - I know you have the mechanical savy to tell if its going to be a bust before you go too far. If it goes together tightly, assemble the fork and see if there are tight spots when you turn the forks... No tight spots, you are probably ok.

2) If the new headset seems snug, but not tight, you can use locktite bearing mount to fix this up.

3) If it is really pooched, see if a good builder can offer up a solution - True North is in Cambridge I think... He has done some titanium work for a friend of mine and he is a true artist... true north!

Cheers

Derek

 

[AndrewTO]

Good points, guys. Thanks!

Ron - exactly why I mentioned the directions I was measuring. Seemed VERY strange to me. To the best of MY knowledge the HT has not been re-cut, unless it was done before I bought the bike - I am the original owner. Unless someone was in the garage years ago with a reamer and ..... naaaaah!

Gear - I noticed that on the CK tech page, hence my asking if the eliptical shape was a "big deal" or not.

THANKS guys! The rebuild begin's. Installing it tomorrow. WOO HOO!

 

[AndrewTO]

I'm thinking like Ron, the elongation is in an odd direction. So am I correct that the headset will be too tight one way, too loose the other by 15 thou? Seems the old headset would have shown some signs of trouble? I know that a vernier is not the weapon of choice for bore measurement...

I suggest these steps:

1) Try to install the new headset - I know you have the mechanical savy to tell if its going to be a bust before you go too far. If it goes together tightly, assemble the fork and see if there are tight spots when you turn the forks... No tight spots, you are probably ok.

2) If the new headset seems snug, but not tight, you can use locktite bearing mount to fix this up.

3) If it is really pooched, see if a good builder can offer up a solution - True North is in Cambridge I think... He has done some titanium work for a friend of mine and he is a true artist... true north!

Cheers

Derek

NOW you post!



Yup, you know me - picky picky picky! When I had everything apart I checked the bearing races and bearings for unusual wear and didn't notice anything that would have caused alarm, but the HT measurement spooked me. Even the OD's on the original bearing races (they're steel) measure alright - top is round within 0.0005", the bottom within 0.002". Going by what GearHead mentions I can only assume the steel race caused some of the eliptical shape in the HT.

Loud and clear with your suggestions, thanks! You already know that's what i'd do, don't you?

True North in Cambridge? Wussat? Custom frame builder??????? Do tell!

 

[airman]

NOW you post!



Yup, you know me - picky picky picky! When I had everything apart I checked the bearing races and bearings for unusual wear and didn't notice anything that would have caused alarm, but the HT measurement spooked me. Even the OD's on the original bearing races (they're steel) measure alright - top is round within 0.0005", the bottom within 0.002". Going by what GearHead mentions I can only assume the steel race caused some of the eliptical shape in the HT.

Loud and clear with your suggestions, thanks! You already know that's what i'd do, don't you?

True North in Cambridge? Wussat? Custom frame builder??????? Do tell!

Hey Andrew!

I was typing my reply at the same time you were...

YOU should know True North Cycles - local custom builder - see them at the spring bike show sometimes, all the O-Cup and Canada Cup races as they sponsor local talent. The bikes are really nice... If you ever retire the Proflex, I'm sure your appreciation of mechanical excellence would make you interested in this builder - they will fit you exactly... custom...

See True North

Cheers

 

[AndrewTO]

Thanks for the link Derek! Nice looking works of art!

Got the headset installed tonight. Eeeeeeasy! Put the bearing cup's in the fridge, put the frame over the radiator (old house), had a beer, then went for it.

My first King component.

THANKS guys!!!!!!!!!!!!!!!!

 

[RonSonic]

Back to the crosslink.
Give up on that telescoping fork fad?

Ron

 

[AndrewTO]

Back to the crosslink.
Give up on that telescoping fork fad?

Ron

HAHAHA! Yeah, you guys don't know what you're missing with it.

Okay, maybe about 2-3" of travel, but....

No, i'm building it up a little more original-like. I'll transfer the Minute to my 5000 frame. Same with the discs.