Mountain Biking - Another shot of the new Giant Carbon NRS...

Sorry, can't read German but this is the link to the forum conversation about it with pics.

Interestingly, looks like an aluminum rear end. Did not really realize it wouldn't be all carbon like the Fuel.

http://www.mtb-news.de/forum/t72979.html

That does look like the same stays that are on the current aluminum NRS's. I think that's opposite how Trek went. I believe the fuels started with carbon stays, then they went ahead and did the whole frame in Carbon.

Very pretty...just don't scratch it. :D

I'm Scared :o....

After seeing the world speed record broken on a mtb and then seeing said mtb shatter...I will never look at carbon fibre again...scary...

iamlucky: You are correct that it's the opposite of how the Fuel started (my current ride). However I think the current NRS rear end has an extra joint near the cassette area.

Maelstrom: There are no speed records in my future.;) I'm woefully ignorant of the incident you're talking about. Who was the rider--any links? Sounds interesting.

MTB speed record?!


Enlighten me!!

I couldn't find a working link to the video, but Pinkbike have pics here (http://www.pinkbike.com/modules/photo/?op=view&image=28402), here (http://www.pinkbike.com/modules/photo/?op=view&image=28403) and here (http://www.pinkbike.com/modules/photo/?op=view&image=28404). Also a news article on it here (http://www.local6.com/news/1458650/detail.html).

Enjoy!

ooooh, found an old thread (http://www.bikeforums.net/showthread.php?s=&threadid=8836&highlight=eric+barone) on it. There's a link at the bottom to video footage.

Thats it...Initially the record was 72mph. He proceeded to break that record on a Giant DH TEAM by going down at 82 mph. He hen hopped on this specially engineered death machine by, I believe, canondale. He shattered thee record by scoring 107mph and then shortly after the speed test line (3/4 of the way down the mountain, the bike split in two. No real bumps, not rough terrain, just snapped in two like a twig. Scariest thing I have seen in a while...that man is very luck.

Well, the subject of CF for mountain biking has come up often and I've commented on it before. I'm lazy so I'll simply cut and paste my thoughts on it from previous posts.


It depends on the construction. There are different ways to construct carbon fibre as there are many different types of carbon fibre. For instance, a thermoplastic behaves differently than a thermoset with regards to impact. Thermoplastics generally exhibit higher impact resistance than thermosets. My MTB's main frame is made of thermoplastic (swingarm and fork legs are also thermoplastic). In actuality thermoplastics can be repaired (and even recycled) by remelting portions and reforming the damaged section although the process would be a bit involved and not recommended for the average consumer/user. You can't really repair thermosets though. Thermoplastics are however difficult to bond with dissimilar materials and delamination can occur easier unless certain precautions are taken in the manufacturing process. This is can get expensive. Many manufacturers also put a very thick clearcoat and/or use multilaminate processes to protect against scratches and nicks.

Just as a further note, very few manufacturers actually produced thermoplastic carbon fibre MTB frames. GT did with the LTS, K2 did with the Oz/4500C/5500C and Cannondale has the Raven (new - old Raven was thermoset). I believe Yeti also made a thermoplastic bike. I'm not sure about the GT and Yeti bike but the K2 and the Cannondale bikes utilised a "spine" construction. In the case of the Raven, the two carbon fibre shell halves were mated to a magnesium spine. K2 used a thermoplastic carbon fibre backbone. I'm not saying all carbon fibre is appropriate for all applications but it is a versatile material that can be adapted for a variety of conditions. And more than any other material, the suitability of carbon fibre is highly dependent on the manufacturing process and design.

The Trek fuel however uses thermoset CF (I don't know what the Giant's CF technology is based upon) and thus there might be some concern about its durability. That said, the Trek Elite 9.8, Kestrel MTB, Aegis ProAxe and a bunch of other thermoset CF MTBs have held up quite well at least in the XC domain. I know from experience and from talking with and hearing from other riders of thermoplastic frames... primarily K2 Oz (ProFlex 4500C/5500C) frames that our bikes can take a lot of abuse without frame failures and someone has actually repaired their frame when a crack showed up.

Originally posted by Maelstrom
He hen hopped on this specially engineered death machine by, I believe, canondale. He shattered thee record by scoring 107mph and then shortly after the speed test line (3/4 of the way down the mountain, the bike split in two. No real bumps, not rough terrain, just snapped in two like a twig. Scariest thing I have seen in a while...that man is very luck.

I remember seeing the footage as well as other footages and images of Eric's bike but I didn't know and still don't that the bike was a Cannondale. However, whoever produced it, it's a very specialized bike... not something engineered for the mass consumer market. Bikes like that really push the bleeding edge of technology and rarely undergo enough (as compared to those designs that make it to your LBS) stress testing before being put to field. Actually many times, fielding it is considered part of the testing phase. These guys are essentially riding prototypes or experimental and immature designs.

Bad time to be riding a Crack-n-fail

Originally posted by khuon
I remember seeing the footage as well as other footages and images of Eric's bike but I didn't know and still don't that the bike was a Cannondale. However, whoever produced it, it's a very specialized bike... not something engineered for the mass consumer market. Bikes like that really push the bleeding edge of technology and rarely undergo enough (as compared to those designs that make it to your LBS) stress testing before being put to field. Actually many times, fielding it is considered part of the testing phase. These guys are essentially riding prototypes or experimental and immature designs.

Oh I do realize that but I base my own opinion on CF on what other have said and how well it holds up to the rigors of Whistler mountain. It is not a very popular product here. Science or now science it just doesn't hold up. Anyways I know squat diddly about material strenghts and physics behind them, sometimes real world testing can be more accurate than the science behind it.

BTW why is it that scratching it causes such severe damage. I have always been curious.

I do agree though, the bike was very specific in design and probably only built to handle one run. I myself can't remember if it was a canondale but I remember thinking it was a boutique company when I saw the logo. It has been a couple of months since I last saw the footage.

Originally posted by Maelstrom
BTW why is it that scratching it causes such severe damage. I have always been curious.

Carbon fibre is a brittle material as oppose to a more ductile material such as steel or aluminum. Carbon fibre can be very tough... stronger than many metals but it can also fail catastrophically rather than gracefully like say steel. Additionally, carbon fibre as a material is aligned and therefore its strengths especially in tensile and compressive mode is longitudinal to the direction of the fibres. A scratch can cross perpendicular to the direction of the fibres and thus create a stress concentration which can lead to cascade failure in the structure as the crack propogates. The main failure mode is delamination. Carbon fibre structures are usually built of layers unidrectionally woven fibre impregnated laminates. Sometimes these directions (from layer to layer) are aligned and sometimes not depending on how the materials engineer wants to bias the strength and directional properties but there does exist an interface between layers that can be broken given enough stress at the boundary and typically there's no reinforcement that crosses the layers to provide strength against seperation of the layers. There is however research being done with "stitching" that involves placing fibres out-of-plane between the laminates.