HeartCoppi

or maybe not...cos weird stuff is known to happen

I assume that this is how the frame was assembled. I ask this because I cant see any degassing apertures for the weld attachment of the down tube and top tube to the head tube. They may now be covered by the reinforcing tube. cont'd The horizontal crack is then answered by your answer as to the assembly. If the cup flanges were welded on, then chickenrun4me and pappa bear and pal prof have some sound contributions. But not entirely. Its clearly related to the HAZ and the quality of post weld HT. But generally: (a) the material is very thin; depending on the weld prep as I detailed above, there may be no wall thickness variation; (b) weld filler metal diameter cools the weld pool; © and my bet that such an esteemed company would be semi if not fully automated to ensure optimal repeatability and quality. (d)As for heat sinking I am not sure as to the jig construction and its influence on heat flow, but it may well balance the equation. It the head tube flange is formed and stiffened then the horizontal crack simply follows a forming line or the last section of single walling before strengthened by double tubing. What do you think? cont'd In my opinion this crack originated from the head set cup and specifically from the inside diameter of the headset cup. Why? Simple maths: the ID is the smaller circumference. and the OD the larger circumference. The race material has a yield strength and elongation value indicative of the point of gross failure. The race is hardened material and is inherently stressed in comparison to ferritic material. Express this as a percentage of the circumference and the smaller ID has the least units required in expansion to express a failure. The crack then exists and simply propagates outward along the stress vector. Eventually the head tube flange will also fail. This is the vertical tear. The aluminium fails because of 'fatigue'(constant expansion and contraction) and then the compressive relationship is lost. It will displace horizontally on the next weakest point on the material which is circumferential. I've covered this discussion. In all though the circumferential crack is consequential and not causative, therefore not the focus. My assumption: A significant outward force was exerted to the inside of the headset cup, presumably by a very strong upward force of the fork into the head tube due to play. (very much like driving a taper into the bearing ring). The broken headset cup then sheared the frame. Difficult one. Good luck with the claim. I think its a tough one. The Frame manufacturer will consult the Head set manufacturer/supplier . The headset manufacturer will have the steel and heat treatment analysed in an independent laboratory. The likelihood of a non-conformance is low to zero. I think you had play across (up and down) the steerer. HeartCoppi2010-02-17 15:57:49

JB, help me out, because I'm not clear regarding the construction of the head tube. I assume you've taken out the cup to study the construction of the head tube. The second picture shows the inside of the aluminium tube with some relatively clean grease. But I cant see a weld root or discoloration that would be evident from a properly penetrated weld. This could have been removed by post weld machining though(or reaming or grinding). From a manufacturing perspective it seems really complex. to weld. Mainly because it involves so much preparation and post weld production steps including inspection and testing (eg ultrasound or Xray). Exceptional material cleanliness is one key to success and requires discipline and process. This is all extra cost to a manufacturer. Think of all the possibilities and the steps required; and the capital investment required before you even strike an arc on the first tube. Three options you haven't clarified pertaining to how it is welded: (1) cup flange is slid over the tube. TIG PULSE AC/DC overlap weld. Geometrically difficult to smooth the radius in to one; with or without filler. (2) tube is undercut, cup flange is slid over undercut section and butts against shoulder. TIG Pulse AC/DC butt weld with filler is easy to locate and machine the radius flow. (3) straight butt TIG pulse AC/DC with filler would be most jig intensive with through form root. But why? Aluminium is such a malleable material. It can be easily spun out or bellowed by press forming. Then an additional tube can be inserted through the tube. This can be fixed in several ways and adds some addition strength. Its cut to critical length to serve as stopper for the head set cup. Simpler and more economical assembly line. In theory. Sorry if I've missed something but I need a personal visual. What do you think? cont'd

Where are you based in Jhb? or which area would you prefer to find a welder?

I'd take it up with your LBS if they taped your bike last. You'd be a good citizen: perhaps the chap in the back is priming the whole community for a fall. If you taped it yourself: stop doing it that way. Use a pencil to mark the angle of the cut on the last wrap and then cut nicely with some scissors.

QUESTION Is it possible that ..? OR Has somebody been....? ...because this is my assumption: Finishing the bar tape or adhesive tape by running or rolling a sharp knife around and on the bar. Thereby scoring the aluminium bar. This will create a "stress raiser" in the bar. It will break on this weak point, just like scoring glass with a diamond edge before tapping it. The handlebar will score quite easily in the soft aluminium. You may have difficulty in seeing the score mark now because it will have 'sheared' on this line. But the photos suggest to me that this is the root cause. It wouldn't necessarily fail immediately but gradually fatigue or extend the crack in the wall thickness under stress due to the plastic nature of most aluminium alloys. tarboy2010-02-14 02:48:53

Yup, a wavy washers acts like a spring when compressed by the nut or screw head. I don't think your LBS will have any trouble getting some replacements. (not a guru) tarboy2010-02-13 16:45:18

Just curious to know if you have any warranty from the dealer or bike shop. Sorry if I've missed something; and I don't know how old the bike is. Is it the result of general material fatigue or a fall? I sorry that I have to disagree when you say "it doesn't seem serious yet..." If its gets down to restoration: Just be sure to ask for a certified TIG welder. Also the bike will have to be stripped down and the problem area will have to be cleaned of all paint, right down to the raw aluminium. It will be good to open up the crack a bit and bevel the sides with a fine triangular file. tarboy2010-02-13 16:33:51

I've found that aviation tin snips make life real easy when cutting through the reinforcements of cable outers.

Consensus is that, as long as it says 'gatorskin' and not 'niksrotag' you should be ok. Clearly its eating at you. So take it off and put it on correctly.

There are not many routes from CT to Hermanus. They may be a lot of peeps in a second peleton. hey, its a public road.

Was the wobble in the hands or on the back wheel?

+1 ravX, even worse exquisite frameset though. Interesting is the 'made in Italy" sticker; and peeking out behind the rim is a "carbonfiber" sticker in a very chinese fonttarboy2010-02-06 07:53:40

Are all tapes imported? I find tape quite cheap overseas +/-R70 for deda, and only R110 for fizik. Banging it in a suitcase and bringing it home is no problem, but buying collectable tapes (de rosa, colnago etc embossed types) on-line and shipping works out hellish expensive because of the volume/weight calculation. So I could see the problem that importers face to bring good prices. I wouldn't mind buying off a roll by the meter for my training wheels. Especially if I can benefit from price. I dont need the fancy box and plugs. I prefer electrical tape anyway to finish. Is this not something bike shops could investigatetarboy2010-01-04 03:06:29

it is: webike.co.za

I thought it was C-Record like the ones below, but they seem diff to the ones you've postedtarboy2009-12-29 11:16:17

ask velo to browse his book.tarboy2009-12-29 11:15:10

really nice bike. you'll have to get a cordless and obviously evaluate the groupset.

It needs quite a bit of work though tarboy2009-12-28 04:00:55

Finally I have one. What a weird deal. I was standing in the parking lot chatting to my old neighbour from my previous house who I had just bumped into. I watched a guy ride past us and pull up to the entrance of "a shop where you can get cash for unwanted goods". He wheeled it into a particular department of this service provider, instead of chaining it outside on the sidewalk. Obviously I greeted my old neighbour instantly and moved. Moved real fast. I worked the guy while he was standing in the queue, and told him that I would give him double what they offer. To cut a long story short I stayed and listened to them offer him R200. We looked at each other and as they say the rest is history. He has told me he has another bicycle that is the same. So we exchanged numbers and I gave him a bit more to keep him interested. So I'm holding thumbs.

But hey when a rider is pumped...he's pumped...you know how it is, or knew how it was? But I agree: You cant educate someone by racing past and swearing at them. This is not a constructive method of teaching bad cyclists the dangers of the road.tarboy2009-12-26 02:55:24