Mountain Bikes & Carbon Frames
11-09-04 | 04:12 PM
#26
Wood Licker
Joined: Apr 2002
Posts: 16,966
Likes: 2
From: Whistler,BC
Bikes: Trek Fuel EX 8 27.5 +, 2002 Transition Dirtbag, Kona Roast 2002
Originally Posted by r0cketrider
Where did all the XC'ers go?
11-09-04 | 04:14 PM
#27
Wood Licker
Joined: Apr 2002
Posts: 16,966
Likes: 2
From: Whistler,BC
Bikes: Trek Fuel EX 8 27.5 +, 2002 Transition Dirtbag, Kona Roast 2002
Originally Posted by r0cketrider
LOL...well being a newb to mountain biking I will have to reserve final judgement of that for myself...however for now I would rather ride across 15-20 miles of varied track that just bomb down the same hill all day long.
...you are definately a xc guy. Although, dh is far more than that and there is usually more than one 'hill' and personally I also hike a bike which gives a lot more options than just lift assisted 
To assume dh is not varried...definately find a REAL dh HILL and call it not varried. haha
11-09-04 | 07:29 PM
#28
I cant get myself to trust anything carbon on my bike except maybe a waterbottle cage...I do mostly free ride stuff and ive read about how some peoples carbon bars snap and that scares me shiftless. Maybe in 10 years if they improve carbon (which they likely will) i will go, as for now its more of a beta
11-09-04 | 07:52 PM
#29
DEADBEEF
Joined: Aug 2002
Posts: 12,234
Likes: 10
From: Catching his breath alongside a road near Seattle, WA USA
Bikes: 1999 K2 OzM, 2001 Aegis Aro Svelte
Okay. I'll be the oddball here. I'm primarily an XC and trail rider. I ride a full carbon frame. The mainframe is made of two ultrahigh-modulus thermoplastic carbon fibre half-shells each with several intermediate-modulus layers underneath that are bonded together to an internal high-modulus "backbone" structure. The design is a hybrid monocoque with internal structural reinforcement. The swingarm is made of high-modulus thermoplastic bladder molded CF. The fork legs also use the same construction process as the swingarm as does my seatpost and handlebars. Fork legs, swingarms, seatpost and handlebars were produced by Easton under license from K2. The main frame was constructed natively at K2.
The bike has survived multiple crashes... some of them pretty horrific. In one crash, I missed an outside line, got flung down the side of a hill and slid a hundred feet with my bike bouncing along after me. In another accident, I stupidly hit a jump bad and endo'ed with the bike flying over me and tumbling end over end. After every crash, I do a UV test with vasoline and a blacklight and I also keep a record of impedence test points that I measure across with an ohmmeter to detect any problems in the frame. There have been several similar stories of nasty crashes and incidents involving the K2 Oz and ProFlex 4x00C series of bikes. In almost all the cases, the bikes survived fine. One guy on the ProFlex Riders Group forums did discover a crack in his frame and successfully repaired it. It wasn't an easy task but the fact that the CF is thermoplastic vs thermoset makes it possible. Additionally, thermoplastics are generally much better at surviving impacts and have less notch sensitivity than thermosets. The biggest issue with thermoplastic construction is that it's much more difficult to bond to metal parts.
The bike has survived multiple crashes... some of them pretty horrific. In one crash, I missed an outside line, got flung down the side of a hill and slid a hundred feet with my bike bouncing along after me. In another accident, I stupidly hit a jump bad and endo'ed with the bike flying over me and tumbling end over end. After every crash, I do a UV test with vasoline and a blacklight and I also keep a record of impedence test points that I measure across with an ohmmeter to detect any problems in the frame. There have been several similar stories of nasty crashes and incidents involving the K2 Oz and ProFlex 4x00C series of bikes. In almost all the cases, the bikes survived fine. One guy on the ProFlex Riders Group forums did discover a crack in his frame and successfully repaired it. It wasn't an easy task but the fact that the CF is thermoplastic vs thermoset makes it possible. Additionally, thermoplastics are generally much better at surviving impacts and have less notch sensitivity than thermosets. The biggest issue with thermoplastic construction is that it's much more difficult to bond to metal parts.
__________________
1999 K2 OzM
2001 Aegis Aro Svelte
"Be liberal in what you accept, and conservative in what you send." -- Jon Postel, RFC1122
1999 K2 OzM
2001 Aegis Aro Svelte"Be liberal in what you accept, and conservative in what you send." -- Jon Postel, RFC1122
Last edited by khuon; 11-09-04 at 08:02 PM.
11-09-04 | 09:59 PM
#30
Wood Licker
Joined: Apr 2002
Posts: 16,966
Likes: 2
From: Whistler,BC
Bikes: Trek Fuel EX 8 27.5 +, 2002 Transition Dirtbag, Kona Roast 2002
And to also put in some possitives. The one guy I do know riding the carbon frame liked it (at least from reports) and it survived some huge crashes.
https://www.bcdracing.com/
Definately a worthy bike but a little out of most people price ranges
https://www.bcdracing.com/
Definately a worthy bike but a little out of most people price ranges
11-09-04 | 10:14 PM
#31
Senior Member
Joined: Sep 2004
Posts: 646
Likes: 0
From: Hamilton, Ontario
Bikes: Rocky Mountain Instinct, Cannondale Six13, Cervelo One
Originally Posted by Grimlock
Formula One racecars aren't meant to be durable, they're meant to go really fast for a weekend. The frame of an F1 car is not made of CF, just the skin.
Just watching hockey sticks explode by the dozen (last year, of course) was enough to get me to stay away from CF parts for a few years to let them (scienticians, of course) figure out how to make it more durable.
Or, you know, until I develop x-ray vision and can spot any hairline stress fracture in a second.
Just watching hockey sticks explode by the dozen (last year, of course) was enough to get me to stay away from CF parts for a few years to let them (scienticians, of course) figure out how to make it more durable.
Or, you know, until I develop x-ray vision and can spot any hairline stress fracture in a second.
Originally Posted by F1Technical
Producing the composites - R24
The right cut
An F1 chassis is not simply composed of one type of material: up to five different types go into producing the finished article, including carbon fibre, resins, and aluminium honeycomb.
" The first step in cutting the carbon fibre is to transfer the digitised files of each part to the Lectra cutting machines" explains Composites Manager Colin Watts. "Once this has happened, the software then collects together all the parts to be produced from a particular material, and organises them as efficiently as possible. One thing we can never change, though, is the orientation of material when it is cut: the fibres must run in a specific direction according to the forces the part is subjected to."
The collection of parts is called a 'marker', and once this is ready, the machine can begin cutting. "For the upper part of the chassis, we cut up to 500 different shapes which must then be laid up in the mould" explains Colin. Cutting all the markers for this part of the chassis takes between two and three hours.
Skins and sandwiches
The chassis itself is composed of three layer: the outer skin, the 'core' and the inner skin, in what is termed a 'sandwich' structure. "The outer skin comprises between 150 and 200 'plies', or cut shapes of carbon fibre" explains Colin.
"We assemble the mould, and then begin 'laying up' the plies according to the drawings from the design office, paying careful attention to the orientation of these pieces. We apply different types of carbon fibre in layers, and the amounts of material vary according to the location on the chassis: certain key areas, such as the engine mounts or the roll hoop, require more material to cope with the forces involved."
During the preparation of the skins, the plies are cooked under pressure in the autoclaves in order to 'de-bulk' them, and squeeze the layers of material together. Once the skin is finished, it is then cured in the autoclave before the core and inner skins are added.
Stiff enough ? Light enough ?
In designing and producing the chassis, designers must constantly balance the conflicting demands of weight and stiffness. The thicker the 'sandwich', the stiffer the chassis, but it is also heavier; a thinner core brings advantages in terms of weight, but will flex more. Controls, though, are strict : "For the sides of the chassis, we must homologate the structure with the FIA" continues Colin.
"We produce a sample of the chassis construction, which is then sent away and tested with an impact equivalent to having the nose of another car hit the chassis."
Once this construction has passed the strength test, it is then fixed for the season.
A ten-man job
During the winter, the composites department works night and day, literally, to produce the chassis. "We have ten dedicated chassis laminators on day- and night-shifts" explains Colin. "We have two upper moulds and two lower moulds in the clean room at any one time, and lay up two chassis simultaneously."
Although the chassis may require the greatest manpower, it is actually an exception to how the composites department usually works. "For almost all other components, a single technician will produce the entire part from start to finish" concludes Colin.
"It is not the most efficient method, but our system is optimised for producing the best quality part. It improves consistency, and also gives the technicians a real pride in their work."
It's the kind of attention to detail that makes the difference in Formula 1.
The right cut
An F1 chassis is not simply composed of one type of material: up to five different types go into producing the finished article, including carbon fibre, resins, and aluminium honeycomb.
" The first step in cutting the carbon fibre is to transfer the digitised files of each part to the Lectra cutting machines" explains Composites Manager Colin Watts. "Once this has happened, the software then collects together all the parts to be produced from a particular material, and organises them as efficiently as possible. One thing we can never change, though, is the orientation of material when it is cut: the fibres must run in a specific direction according to the forces the part is subjected to."
The collection of parts is called a 'marker', and once this is ready, the machine can begin cutting. "For the upper part of the chassis, we cut up to 500 different shapes which must then be laid up in the mould" explains Colin. Cutting all the markers for this part of the chassis takes between two and three hours.
Skins and sandwiches
The chassis itself is composed of three layer: the outer skin, the 'core' and the inner skin, in what is termed a 'sandwich' structure. "The outer skin comprises between 150 and 200 'plies', or cut shapes of carbon fibre" explains Colin.
"We assemble the mould, and then begin 'laying up' the plies according to the drawings from the design office, paying careful attention to the orientation of these pieces. We apply different types of carbon fibre in layers, and the amounts of material vary according to the location on the chassis: certain key areas, such as the engine mounts or the roll hoop, require more material to cope with the forces involved."
During the preparation of the skins, the plies are cooked under pressure in the autoclaves in order to 'de-bulk' them, and squeeze the layers of material together. Once the skin is finished, it is then cured in the autoclave before the core and inner skins are added.
Stiff enough ? Light enough ?
In designing and producing the chassis, designers must constantly balance the conflicting demands of weight and stiffness. The thicker the 'sandwich', the stiffer the chassis, but it is also heavier; a thinner core brings advantages in terms of weight, but will flex more. Controls, though, are strict : "For the sides of the chassis, we must homologate the structure with the FIA" continues Colin.
"We produce a sample of the chassis construction, which is then sent away and tested with an impact equivalent to having the nose of another car hit the chassis."
Once this construction has passed the strength test, it is then fixed for the season.
A ten-man job
During the winter, the composites department works night and day, literally, to produce the chassis. "We have ten dedicated chassis laminators on day- and night-shifts" explains Colin. "We have two upper moulds and two lower moulds in the clean room at any one time, and lay up two chassis simultaneously."
Although the chassis may require the greatest manpower, it is actually an exception to how the composites department usually works. "For almost all other components, a single technician will produce the entire part from start to finish" concludes Colin.
"It is not the most efficient method, but our system is optimised for producing the best quality part. It improves consistency, and also gives the technicians a real pride in their work."
It's the kind of attention to detail that makes the difference in Formula 1.
11-10-04 | 04:40 PM
#33
I drink your MILKSHAKE
Joined: Jul 2002
Posts: 15,061
Likes: 3
From: St. Petersburg, FL
Bikes: 2003 Specialized Rockhopper FSR Comp, 1999 Specialized Hardrock Comp FS, 1971 Schwinn Varsity
Originally Posted by Mtnbike247365
I xc and I am getting the trek fuel 70 in a few days, now that I know that It isn't cf it is something to get
__________________
