With all the carbon “me-too” hard tail introductions of late, it is nice to see something refreshing coming down the pike. Giant has delivered with the soon to be released XtC Composite 29″er hard tail bike, which was pimped today on their Facebook site. Following is an image grab from a catalog and from the video featuring Carl Dekker.
Click the link for the video to get Carl’s take on this very unique looking rig. We’ll hopefully have more for you on this soon. Stay tuned……
Are those Giant rims tubeless ready?
@Yourdaguy: There was some talk of Giant coming out with a rim strip- similar to a Stan’s idea- for their rims, but I have not had it confirmed that they have done so yet. At this point, it would be foolish not to have something available to set their wheels up tubeless, but we will see if we can find out more.
looks good but not sure about assymetric chainstays , but the graphics on them is very clever , with the giant logo in the inside of the raised chainstay shows in the driveside view
Some subtle practical design work there.
Slight curve in the seat tube allows a shorter chainstay, and the assymetric design of those maintains the strength without compromising chainring size.
With the release of this model the boutique 29er brands are going to have to lift their carbon game I suspect.
Very very interested in this bike.
subtle practical design work? the curved seat tube is essential to short chainstays on a 29er unless you use an offset seattube but then you have even less support for the bb.
but assemetric chainstays,, why not use the drive side style on both sides then at least any flex in the back end will be symetrical and they tyre contact patch is more likely to stay on the centreline of the bike ,,
why not just go the whole way and design a singlesided back end without any support on the drive side,,, be an interesting look with a lefty front end..
be good for belt drive , ( if it could support the tension) and plenty of heel clearence
Adrian Ward; most people don’t realize that the rear wheel doesn’t flex the same on each side due to different offsets. It looks to me as though Giant has tried to equalize the flex by making the frame stiffer on one side. Also, in this flex equation, the flex of the chain stay is different from each side because the left side is acting through a longer lever arm than the right with respect to the chainring. It looks to me like they might have looked at all these factors and then designed to equalize the sides.
@Adrian Ward: The notion of belt drive, as it is currently designed, is not at all compatible with short chain stays and generous tire clearances, much less the enormous proportions of a bottom bracket/downtube/chain stay configuration as seen on this Giant example.
Unfortunately, unless Gates or someone else can overcome the inherent design limitations of the current belt drive cogs, something as you suggest will never see the light of day.
Specific to this bike: I see the design solution offered here as a way of using carbon fiber to its maximum potential and Giant’s way of saying that a symmetrical design is not the best solution for their goals. I have spoken with other 29″er thinkers that also feel asymmetrical design may be the best solution for getting shorter chain stays, better tire clearances, and better lateral and torsional stiffness in the bottom bracket area.
Of course, the proof is in the pudding, as they say, and we will see how this bike is received once it is offered for sale. I think we may be seeing more of this sort of thing in the future, and it is a refreshing take on design for a carbon fiber bike, at the very least, in my opinion.
i may be wrong here,, I have been before,, a rear wheel should be about the same lateral stifness in both ways as the drive side spokes are under more tension than the greater offset lefthand side spokes ,, to keep the wheel centered ,
if you look at a vertical load on the wheel there would be very little lateral resultant into the rim caused by the different spoke tension , but with the assemtric chainstay design i suspect the two sides would not flex either in the same plane or even bend in the same place giveing possibly more movement on the weaker drive side ,,
in my thinking a bike should be symetrical along the center line ,,
i might be mistaken by this and would welcome any comments ,, i would like to think I am open minded
How do you know the drive side is weaker than the non-drive side?
I do love these internet armchair engineering discussions.
if the drive side was stronger wouldnt you use it both sides?
Nope. Might be heavier.
@GT – totally agree that it is great to see various CF design solutions explored, especially as you and GG are doing the exploring for us. The Cloud 9, Chiru, and now this Giant, as well as all the European offerings,c_g is reporting and the latest Superfly frames, are plain fascinating to see. CF lets us design from the inside out, in a way, and opens up a lot of fresh approaches for different design goals.
As for assymetrical chainstays, etc. – these show up on the elite carbon road machines a lot now. Any reason an MTB version would not benefit similarly?
mm possibly you may be right
Armchair engineering, I love that.
A friend of mine got his engineering degree by designing and building a carbon rim. His first reaction to the asymetric nature of this frame: “Sure, why not?”.
Saw this bike as a prototype in my local bike shop in October. The owner is a ex-Giant works Euro champion who now works as a development rider for Giant. I can tell you there is a lot of stuff through that shop that “does not excist”. Nice to see that there were only minor changes. To be honest, I didn’t notice the assymmetric chainstays when I had a look at it then.
@ adrian ward: It is easy to assume that both of the chainstays will “flex” differently because they are not the same geometry (symmetry). It isn’t like the asymmetric chainstay design is new….FS bikes have been using this for a while. Besides the beauty of carbon design can lie within the layup of the fibers. With the right layup the drive side and non-drive side stays can be designed to be virtually the same “flex”.
It is, as GT and others have pointed out, great to see designs being developed that use the unique qualities and potentials of CF to go beyond just a lighter HT frame. I am certainly no engineer, armchair or otherwise, but it sure makes sense to me.
I even mused about this on my blog (gratuitous blog plug here…http://vintageone.blogspot.com/2011/02/more-carbon-fiber-thoughts-going-above.html)
Bully, I say. Keep it up.
grannygear
GT, you mentioned an offset down tube on your other blog. Details? I assume it is discussed in the videos but I have yet to find a way to skim that very anolog media like I can a block of text.
Where are the videos?
@shiggy- best I can tell the downtube is offset to the nondrive side where it meets the bottom bracket, letting it be massive without interfering with drivetrain.
Am I right? Do I get a prize? A new Giant composite?
@WKilburg
Look for the link in the first paragraph of this article…references Carl Decker.
grannygear
Can an Anthem X 29er Advanced (composite) be far behind…
If I understand articles I’ve read earlier, the chainstays can be asymmetrical without causing flex issues because the forces on the drive side are different than those on the non-drive side and therefore it wouldn’t make any sense at all not to maximize the design for the forces at play. Replicating the drive side stay on the non-drive side would be overkill.