7005 Head Tubes Cracking

[bikeworkshop]

Maybe the ancient Egyptians were right though, break it and then it's waiting for your in the afterlife ready to ride, tyres always inflated, gears fully indexed, fork smooth and plush and silent

 

[Mkane]

So I take it my 6061 frames safe?

 

[Betsy]

Maybe the ancient Egyptians were right though, break it and then it's waiting for your in the afterlife ready to ride, tyres always inflated, gears fully indexed, fork smooth and plush and silent

That’s one school of thought.. I’m more inclined to believe.. Tutankhamun bought 4 ornamental chariots during a plague of locusts when they all had to stay indoors for 12mths.. hung them on his pyramid wall, never rode any of them.. then on his passing folks buried them rather than having to list them on sphinxbay..

It’s a story as old as time..

 

[d8mok]

Right .... So im getting to the point where i need to fit headsets in my Ku's.

Spent a little time digging around last night and a alarmingly large amount are cracked on the headtube. I think out of around 45 known frames around half that or maybe more are cracked.

My 97 is Easton Elite Program Taperwall 7005 and my 98 is Columbus Altec2 Megatube 7005.

The 97 is 33.9 and 98 is 33.95 inner diameter (using cheapo digi callipers). If you place a cup into the headtube you can feel the 97 will be a tighter fit before we even get started.

I'm going to go with a cane creek headset as I used one successfully in my Pace when worrying about the same issue. The headset measures 34.00


I'm tempted to turn a tiny bit off the headset so its a easier fit. Take it down to the same diameter as the headtube? Bikes won't be ridden as they will be wall hangers. Also will look to put the relief channel in too if its worth it (for a non rider)

@danson67

 

[bikeworkshop]

Right .... So im getting to the point where i need to fit headsets in my Ku's.

Spent a little time digging around last night and a alarmingly large amount are cracked on the headtube. I think out of around 45 known frames around half that or maybe more are cracked.

My 97 is Easton Elite Program Taperwall 7005 and my 98 is Columbus Altec2 Megatube 7005.

The 97 is 33.9 and 98 is 33.95 inner diameter (using cheapo digi callipers). If you place a cup into the headtube you can feel the 97 will be a tighter fit before we even get started.

I'm going to go with a cane creek headset as I used one successfully in my Pace when worrying about the same issue. The headset measures 34.00


I'm tempted to turn a tiny bit off the headset so its a easier fit. Take it down to the same diameter as the headtube? Bikes won't be ridden as they will be wall hangers. Also will look to put the relief channel in too if its worth it (for a non rider)

@danson67

You could turn it down to same size then fix it in place with "bearing fit"
This can be used on motorcycle wheel bearings in this situation, so it should be up to the job

 

[JonSus]

Thanks for all the replies, Good info. I remember when I was first building the frame up and picked the new Dia-Compe/Cane Creek headset. I usually always used Chris King headsets. That choice might have saved me from a hard crash... Back in the 90s I faced and chased the head tube with a Bicycle Research tool so it was opened up some from its original size and I was in the habit back then of deburring the edge with a hand deburring tool so that was most likely done also. Maybe not enough though? This wasn't an Answer frame so it wasn't anodized either, just polished. The weird thing is the shop I worked at back then sold a lot of Answer frames and they almost always had King headsets in them and none that I remember came back with cracks. I think I have a plan to make sure this doesn't happen to any more of my frames. I don't have access to a machine shop anymore but I do have a mini lathe. I'll try and figure out a decent way to chuck a headset up in it to cut the relief and make sure the fit is on the looser side from now on. Sanding probably wouldn't get down in the corner like it would need to. Maybe just a file on the lathe would be fine? Most of my old bikes don't get ridden and I have a few other cracked frames in my collection so I probably won't fix it, just build it up as is and let it look pretty.

 

[d8mok]

You could turn it down to same size then fix it in place with "bearing fit"
This can be used on motorcycle wheel bearings in this situation, so it should be up to the job

Yeh I’ve got some locktite stuff I’ve never used for press in BBs

 

[bikeworkshop]

This will deffo reduce stress.
Both the headtube and yours

Personally I'd leave 0.05mm or less (like "a thou") interference, and use bearing fit to reduce the risk of slipping.

@danson67 said all this earlier, but sometimes clarity is helped by repetition

 

[Mkane]

Called stud & bearing mount. Green bottle