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Slowtwitch Forums: Triathlon Forum:
Gerard Cervelo P3 weld question

jpmadzin

Jan 16, 03 13:07

Post #1 of 6 (255 views)

Gerard Cervelo P3 weld question	Can't Post

Gerard,

I was at a bike shop this weekend looking at a P3 frame and had a question about the welds on the frame. I noticed that the welds at the point were the downtube and the bottom bracket meet was noticeably different. On the drive side of the frame the welds were extremely thick, almost like it was double welded, and the non-drive side the welds were normal size. Obviously, this was for added strength on the drive side of the bike, but the other bikes that I�ve looked at the welds are about the same size on both sides (QR-Caliente and 0-Gravity). My question to you, have you had any breakage at the bottom bracket in the past, and should I be concerned about this before I buy.

Tom Demerly

Jan 16, 03 13:35

Post #2 of 6 (244 views)

Re: Gerard Cervelo P3 weld question [jpmadzin] [In reply to]	Can't Post

I am not qualified to answer for Gerard and am not doing so. I can tell you that, as a Cervelo dealer, we have not had a single frame failure on any of their models and we have a very substantial number of them on the road. At least four of these bikes have been subjected to crashes that would have caused many (lesser) bikes to fail. Our experience is that their weld quality is beyond question at this point.

brad in WA

Jan 16, 03 16:18

Post #3 of 6 (213 views)

Re: Gerard Cervelo P3 weld question [Tom Demerly] [In reply to]	Can't Post

I too am not qualified to answer for Gerard and am not doing so. I have read nearly all of his posts, and he seems quite proud of the stiffeness that they have accomplished. perhaps this isn't too protect from failure, but to beef up the stiffness w/o resorting to oversized tubing?

just a theory.

brad
my next race?
undecided.

gerard

Jan 16, 03 16:31

Post #4 of 6 (207 views)

Re: Gerard Cervelo P3 weld question [jpmadzin] [In reply to]	Can't Post

[reply]My question to you, have you had any breakage at the P3 bottom bracket in the past, and should I be concerned about this before I buy.[/reply]

Easy answer: The P3 is arguably the strongest frame with regards to the weld design and excecution. We have had ZERO issues.

And the P3 has also passed the Efbe fatigue test, arguably the toughest standardized fatigue test in the world. I don't think any other company has had a tri frame pass the test at Efbe.

But in all fairness, I have little doubt the Cannondale tri bikes would pass the Efbe test as well, as other Cannondale models have passed the Efbe test and it seems that Cannondale prefers to do in-house testing over spending the big bucks at Efbe, which is understandable. Their in-house lab is outstanding.
Gerard
Cerv�lo SA

Note: This forum is not my Inbox. Please choose: Slowtwitch cust. service or Cerv�lo customer service.

gerard

Jan 16, 03 16:44

Post #5 of 6 (203 views)

Re: Gerard Cervelo P3 weld question [brad in WA] [In reply to]	Can't Post

[reply]I too am not qualified to answer for Gerard and am not doing so. I have read nearly all of his posts, and he seems quite proud of the stiffeness that they have accomplished. perhaps this isn't too protect from failure, but to beef up the stiffness w/o resorting to oversized tubing?

just a theory.[/reply]

You really can't equate stiffness with strength, in fact stiffness in the wrong areas can actually decrease the strength. Think about an airplane wing, not particularly stiff but quite strong, and with excellent longevity.

I don't really want to say too much about this, but it is shocking what a lack of knowledge there is at most bike frame welders when it comes to how to make a good weld. Most welds are very poor, they look nice but they could achieve fatigue lifes that are many times better than they are if they actually knew how to make a strong weld instead of a pretty weld. We spend a lot of money on this aspect, but we save it on the other end since our frames have such good longevity.
Gerard
Cerv�lo SA

Note: This forum is not my Inbox. Please choose: Slowtwitch cust. service or Cerv�lo customer service.

cjeder

Jan 16, 03 17:12

Post #6 of 6 (191 views)

Re: Gerard Cervelo P3 weld question [jpmadzin] [In reply to]	Can't Post

I am by no means an expert in the area of frame design, but I can confidently say that I have never seen a frame builder use asymmetric welds. Furthermore I cannot see any compelling reason to do so. As far as I know a bike frame generates its strength and stiffness by use of tube material, size and dimension. Creating a larger, 'stiffer' weld without increasing the wall thickness of the tube will create a stress riser; depending on the position of the oversized weld, frame failure is a possibility.

That said I have found that on smooth welded frames with unusual tube and joint shapes, builders tend to fill in unsightly voids with weld material to provide a smoother more aesthetic, and perhaps more aero appearance. On an aero frame like the P3 I would assume that such a build up of material would be found above the bottom bracket where the down tube and seat tube join. It might be that one side of the P3 frame you are looking at received a bit more filler than the other, If this is in a low stress area that is already reinforced by the number of tubes in the area it probably will never be a problem, and if it is it should be covered under the frames warranty. Given the Cervelos great reputation it may merely be a cosmetic flaw.

Of course an asymmetric weld may be intentional, find out if other cervelos appear to use the same type of weld. My guess is that they don't. All things considered you need to be confident with the frame. If you are paying good dollar for a top of the line frame and want one with a different weld you have the right to request it even if the improvement is only aesthetic. You might peve the owner of the shop a bit, but the worst case scenario is that they sell the frame to someone who doesn't notice that weld.