Possible prevention of head tube blowout on Kinesis aluminum

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- August 18, 2011 at 8:25 pm
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mixalive
Member

It appears a lot of folks with the (made for Barracuda) Kinesis aluminum frames are beginning to show signs of fatigue in the form of cracks. These cracks are showing up at the top and bottom of the head tube and the seat tube. This article deals with a possible prevention of head tube fatigue.
My idea was to machine a ring that could be pressed over the top and bottom of the tube providing support in the blowout areas. I decided to use chrome moly steel for my rings. I ordered a 1 ft section of cromo tubing from Aircraft Spruce, and had rings machined thin enough so when pressed on the head tube, they would not conflict with the intersecting tube welds. I was charged just over an hour for labor for the machine work.
To prep the frame, I wrapped masking tape around the tube where I thought the ring would butt up to, and used a mild paint remover to strip the tube down to metal.

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- August 18, 2011 at 8:28 pm
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mixalive
Member

After measuring the head tube, I realized it was not perfectly round due to distortions when the frame was originally welded. So I decided to fit the ring to the tube instead of having the inside diameter of the rings machined to fit. I used a sanding drum chucked up in my drill press set to the slowest setting of about 400rpm and worked it down to about a 0.1mm smaller than the tube diameter.
- August 18, 2011 at 8:31 pm
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mixalive
Member

I then taped off the head tube and applied red Loctite to the tube and ring.
At 0.1mm, the ring pressed on fairly easily. I didn’t want it to be too tight as to stress out the head tube.
- August 18, 2011 at 8:31 pm
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mixalive
Member

After letting it cure over night, I primed and painted the rings.
- August 19, 2011 at 1:53 pm
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mixalive
Member

Now, if your frame is already cracked in these areas, it would have to be your call if welding up the cracks and adding rings would be safe. I felt confident on my bike as I did not have any cracks yet.
Understand: Aluminum has a finite life and it is just a matter of time until it will begin to fatigue.
- August 19, 2011 at 8:37 pm
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cudarider1
Member

Again I’m super impressed Mix! Great job and glad you could use that pic of my broked cuda.
- September 2, 2011 at 3:58 am
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Mark
Keymaster

Wow.. Truly great write-up!
- November 17, 2012 at 8:38 pm
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ctk
Member

Superb- and that XX is sweet!
- November 17, 2012 at 10:54 pm
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neo_pop_71
Member

Brother Mix is the Zen master of Cuda repairs…

“Snatch the pebble grasshopper, only then will you be ready…”
- November 18, 2012 at 12:45 am
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mixalive
Member

I have a bunch of those machined rings laying around. I would weld up and ring that cudarider frame in a heartbeat.
- November 18, 2012 at 6:49 am
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neo_pop_71
Member

That’s mighty kind of you Mix… however Cudarider hasn’t logged in on this board in over 3 months. I doubt he’ll be taking advantage of your kindness any time soon. Shame…
- April 22, 2013 at 4:58 pm
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mixalive
Member

Well if anyone else has a Barracuda/Kinesis frame with a head tube blowout, I may be interested in purchasing. Especially a 14 or 16 inch. Better to have it on the trail than on the wall as art. :ugeek:
- October 18, 2013 at 5:15 pm
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mixalive
Member

I have a bunch of those machined rings laying around, if anyone wants to reinforce their aluminum head tube..
- October 19, 2013 at 3:09 am
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neo_pop_71
Member

I needed 2 of those on my Swobo Otis… one for the top and one for the bottom… thank God they sent me a new frame!!!
- October 20, 2013 at 2:12 am
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mixalive
Member

That’s messed up.. That’s why it’s all beefed up in the first place. To prevent it from cracking. I think a lot of head tube cracking is due in part to a lack of detail when fitting the bearing cups with too tight of fit.
- October 20, 2013 at 2:24 am
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neo_pop_71
Member

@mixalive wrote:

That’s messed up..

That’s 7000 aluminum for ‘ya… just like all the Cudas that have cracked! 🙄

Maybe I’ll take a pair of those machined rings for the new Folsom they sent me. It would be nice to avoid that messed I went through with the Otis. It still surprises me since the bike was only a few years old and hadn’t been used on trails.