i**********g
发帖数: 159 | 1 carbon fiber is a interesting material which combines very awesome tensile
strength and toughness. The tensile strength mostly comes from the fiber and
the toughness comes from the thermoset or the resin. It is very good on
damping the vibration without yielding, or we can call it very good on
absorbing the impact/ very tough and this is why a lot of cyclists say
carbon fiber frame is comfortable. Most carbon fiber frames are designed to
be elastically deform a little bit to absorbed the vibrati |
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w******x
发帖数: 4396 | 2 both steel and titanium have endurance limits, so when it comes down to
fatigue, properly engineered ti, steel and carbon fiber frames are on equal
terms. they last forever.
ti is way heavier? no. the lightest production frame on the market has been
ti for many years. one day a lighter carbon fiber frame will come by, but
not yet.
most steel tubings are 4130 variants. ti alloys are 3al/2.5v, 6al/4v and 5al
/2v.
aluminum will fatigue regardless of how light a repetitive load you apply.
so all alu |
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h******2
发帖数: 1498 | 3 the "tensile strength" you guys are talking about, is the pulling force
applied to the material until it breaks (or permanently deforms), right?
but for a bike frame, most of the force is in the vertical direction (
compression force from road vibration) and in the form of lateral torque (from the pedaling force applied to the BB). there seems to be little tensile load applied to the material, so why does the tensile strength matter so much? |
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w********6
发帖数: 12977 | 5 In last issue of cyclist, the first dream bike introduced is ti one, weigh
an insane 13 lbs |
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w******x
发帖数: 4396 | 7 if a tube bends, one side is compressed while the other side is pulled.
since solids don't compress much, it's the ability to withstand tensile load
that matters.
bike frames are triangulated tubes. if you load the dropout, the chainstay
is under tensile load, as is downtube. torsional forces like pedal mashing
will also result in tensile load somewhere.
from the pedaling force applied to the BB). there seems to be little
tensile load applied to the material, so why does the tensile strength |
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w******x
发帖数: 4396 | 8 sheldon doesn't take into account the fact that frames of different
materials absorb/transmit vibrations of different frequencies. comfort of a
frame is determined by how much energy is eventually transmitted to the butt
, which depends on the absorption spectrum. |
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V*****n
发帖数: 893 | 9 true! many older bike builders and designers don't understand this concept.
Grand Peterson once wrote in this newsletter that carbon frames can't be
more comfortable than steel one because CF is stiff. He think the comfort of
the frame is only from its deformation to absorb energy.
a
butt |
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i**********g
发帖数: 159 | 11 Titanium, Aluminum alloy and carbon fiber do have different properties on
fatigue. Carbon fiber material has at least
30% more life cycles. Nothing will last forever, when application excess the
design, it will fail.
Compare to carbon fiber, titaniium's specifc weight is too much. It is
almost the 3/5 of steel if I remember it right.
For carbon fiber material, most of the weight comes from resin instead of
fiber.
How can you rebuild aluminum frame to solve the fatigue issue? Re-weld? What is you |
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h******2
发帖数: 1498 | 12 here is a practical question for you guys:
is it a good idea to store bikes in the garage, where the temperature may
raise up to 120 to 130 degrees on a hot summer day?
wouldn't the thermal expansion and cool-off subject the bike to stress/load?
how does that stress or load cycle compare to say a regular 40-miler? |
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w******x
发帖数: 4396 | 13 "Titanium, Aluminum alloy and carbon fiber do have different properties on
fatigue. Carbon fiber material has at least 30% more life cycles. Nothing
will last forever, when application excess the design, it will fail."
er, no. below the fatigue limit ferrous alloys do last forever.
"How can you rebuild aluminum frame to solve the fatigue issue? Re-weld?
What is your point?"
you need to read the post more carefully.
"It is ridiculous to say it will fatigue just by itself. If there is no
vibration |
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i**********g
发帖数: 159 | 14 I dont believe spokes take compressive load. It should be tensile load only.
two problems with carbon fiber as of now. one, it's not scratch resistant.
while ti and steel will deform before they break, carbon fiber will break in
a more violent manner once a stress riser is created. two, it doesn't take
compression load nearly as well as tensile load. mavic's carbon spokes on
their top end wheels were just the latest victims. |
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V*****n
发帖数: 893 | 15 then, you should do some reading on the Mavic R-sys wheels.
only.
in |
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w******x
发帖数: 4396 | 16 you don't need to worry about it. all you can do is looking out for cracks
in the highly stressed parts of the frame, like the chainstay-bottom bracket
area, downtube-headtube weld, etc.
the way they overbuild aluminum frames is they set a target life cycle, more
than vast majority of the riders' needs. say, for example, 5 years @ 10k
miles/yr by a 170lbs rider with a peak force on pedal ~600lbs. safety margin
/redundancy is then added--say, the frame should last over 10 years @
20kmiles/yr by 3 |
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f****i
发帖数: 20252 | 17 帮你看的，Giant的Large，适合你
看照片是2006 OCR C2碳架，但是文字说明是2005 OCR 3铝架 |
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w********6
发帖数: 12977 | 18 主要是我看cyclist杂志里面碳架的review, 说骑车经过坑坑洼洼的路面，如履平地，
说的俺现在骑
铝架过粗燥路面如同震骨机的心里痒痒 |
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g**********r
发帖数: 1654 | 19 我是穷人，是铝架。
Saddle我用的是Sella Italia Gel Flow Diva。很舒服，而且也不重。当时买车的时候
拿去店里让他们把原来的saddle卸下来，他们也说是好saddle。
Seatpost是合金的。
等我以后有钱了，就买一辆碳架的车。。。 |
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m*******r
发帖数: 339 | 20 1. 骑的是什么车子？碳架还是铝架?
2. 骑的是什么样的路？
3. 骑了多久手臂疼? |
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t********t
发帖数: 5415 | 21 105还勉强能算起步（更倾向enthusiast），碳架这个就...
另外1000-1500是车钱还是车+配件钱？（头盔，灯，maybe锁，以及以后可能的trainer
，锁鞋等等）靠点谱的铝架105打折时候都不到1000，tiagra更便宜。 |
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O*******e
发帖数: 6055 | 22 不应该把，我的beretta 和 p01都是铝架的，现在各打了700多发，枪架导轨只能看到
轻微的擦痕。。也就是黑色的finish有一点磨掉。。。 |
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O*******e
发帖数: 6055 | 23 是啊，beretta第一段rail的前端磨损最严重，那就不叫磨，应该叫啃。。。
po1就那样。里面都是本色~~~
决定进一个polymer枪架的。。xdm 4.5 9mm，不锈钢套筒的。。要与时俱进，要接受新
事物。。~~~ |
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O*******e
发帖数: 6055 | 24 也不是拉，
cz如果磨损，一个颜色也能看出来。。cz就是没有。。
所以说我的beretta有问题啊。。。感觉枪架也太柔嫩了，咋整。。。 |
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c*****y
发帖数: 5747 | 25 晕调兄弟，所言极是
226铝合金枪架的最大缺点就是磨损太快，
俺的三把226都是这样，黑水版俺一直舍不得打正是如此，
X5会好些，也是有限。
除非买全钢版本。
全钢版本我有四把，打得最厉害的有一千发左右，基本没有磨损（轻微的肯定有） |
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p*********l
发帖数: 26270 | 27 问题是那东西降起价来，买了原价的会想投河
同样是1800，原价只能买个铝架的，运气好的话能买个碳架的 |
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m******r
发帖数: 9604 | 28 用老路车踹(碳架+UT混105)。新车是铝架+105, 没老车好 |
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q*z
发帖数: 13362 | 31 你那个就是个定死的框吧,还是塑料的
感觉homedepot买个铝架DIY也比这个结实多了.
通常意义说的稳定器不是你这种.
你这个就叫做低拍架. |
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C****c
发帖数: 9157 | 32 买不到， $1000的整车基本是铝架+碳叉
我朋友买的specialized最便宜的碳架要$1700 |
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b******g
发帖数: 3616 | 33 K40x和C10大小和承重上差很多。这个K40X是最大号的球头，自重就有1.5磅，和我原来
大铝架的Manfrotto头差不多重，但标秤的max load有70多磅，比我原来那个高了很多
。这种头是配大架子的，而C10应该是配旅行轻型架的。
expensive |
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gr
发帖数: 2958 | 34 黄老大推荐个低端的！最好自带独角架那种。
目前看好的两个 mefoto的 和sirui的铝架。
不知道mefoto都是5节的会不会不好用麻烦。还是最好上sirui四节？
承重17lb什么的应该够了吧？60D+双狗+430 |
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i*********5
发帖数: 19210 | 35 我的惯用建议：
入门级：$1000-$1500，铝架+105或者Ultegra（打折多时能拿下，现在正好季末折扣多）
中级：$1500-$2500，碳架+Ultegra
多去几家local bike stores（LBS）转转，试骑试骑。不要在网上买，除非你已经骑过
同一款的同一个size。更不要去买BD的山寨车。 |
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i*********5
发帖数: 19210 | 36 我的惯用建议：
入门级：$1000-$1500，铝架+105或者Ultegra（打折多时能拿下，现在正好季末折扣多）
中级：$1500-$2500，碳架+Ultegra
多去几家local bike stores（LBS）转转，试骑试骑。不要在网上买，除非你已经骑过
同一款的同一个size。更不要去买BD的山寨车。 |
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i***s
发帖数: 39120 | 37 郭晶晶
霍家豪宅将变礼堂
霍震霆长子霍启刚与“跳水皇后”郭晶晶恋爱8年，终订在两个月后11月11日结婚。以一对新人童年照作主题的立体请帖近日已陆续送到各宾客手上，霍家沙宣道大宅亦将在届时破例变身成礼堂，供刚晶举行隆重宣誓仪式，缔造婚盟。而日前本刊更拍得晶晶在国内亲友陪同下在港赶办嫁妆。
上周二（11日）傍晚约6时，素颜穿过长牛仔裤的晶晶在国内亲友陪同下，由挂有中港车牌的房车接载到铜锣湾开平道一号Cubus商厦，行动低调掩人耳目。晶晶与一男一女亲友逗留Baccarat水晶店，选购摆设作回礼礼品，约1小时后，晶晶满意甜笑落楼，但对本刊有关办嫁妆提问笑而不答。
会展摆酒150席
有报道指刚晶婚礼因受到霍家争产风波影响而缩皮，须转往亚洲博览馆举行，但据本刊收到消息，证实属流料一则，婚宴地点在湾仔会展新翼筵。
一百五十席，体面又方便，场地更早在年多前预订。据知情人表示：“刚晶婚事筹备了好长时间，宾客都是城中官商名流，绝对不容失礼，除了一早预备了巨额婚礼预算，酒席也早就订好。霍家上下商议后，也决定当日中午先在大宅行礼，启刚是长子嫡孙，大宅由阿爷霍英东年代已兴建，没有地方比大宅更有意义、更适合。”
... 阅读全帖 |
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h*******r
发帖数: 84 | 38 史战 于 March 10, 2002 :
中国军事天地: http://www.chinajunshi.com
自从喷气式飞机问世以来，核武器的出现使远程轰炸机具备了惊人的
毁灭力，空中力量成为战争的决 定因素。空军的建军思想也全部集
中在两大目标上：以核武器轰炸敌方和阻止敌方的核轰炸。然而，60
年 代中期，以核大战为目标建立起来的美国空军，却在越南战场上
连吃败仗。越战的教训对现代空战理论产 生了重大影响，各国空军
的发展由此进入了一个新的时期。
速度与机动
越南战争初期，越南北方的防空网主要由简陋的高炮组成。1964
年，北越境内只有20座防空预警雷达 、1500门高炮，没有任何战斗
机及防空导弹，可供喷气机起降的机场也只有两座。1965年，越南人
民军装 备了36架米格—17n从专业角度来看，米格—17的设计思路在
当时已完全过时n朝鲜战争的经验曾经告诉飞 机设计师们，战斗机性
能必须朝高空高速发展，以便于在进人格斗前能够拥有足够的能量以
进行转弯，或 至少能够逃离对手的机炮射程。但米格—17只比朝鲜
战争中的米格—15稍快一些，它的对手F—105却运用 60年代的航空
技术 |
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a******g
发帖数: 13519 | 39 怎么周围这么多农民啊？扒铝皮来了？搞得像强制拆迁现场。 |
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m*****e
发帖数: 10963 | 41 楼上貌似5毛和小将骂起来了？自己人不认自己人？
几位拉偏架的都拉不住。。。
这年头。。。 |
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w**k
发帖数: 320 | 42 北约不行能起飞的战斗机都没几架了
还得靠美帝才行啊 |
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H********y
发帖数: 3322 | 43 我需要给我的相机弄一个这样的外框, 这样可以在上面直接架很多外部设备, 比如外接
MIC, 外接的灯. |
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j*******9
发帖数: 131 | 44 铝的，很轻，尺寸是 18"*8"*66"
你说个价？ |
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w******e
发帖数: 493 | 45 ☆─────────────────────────────────────☆
TomBrady (Be a Sunday QB,not monday morning) 于 (Tue Jan 22 23:43:34 2008) 提到:
☆─────────────────────────────────────☆
Victoon (Victor) 于 (Wed Jan 23 00:13:37 2008) 提到:
depends on how much you pay. each material can be light, or not.
the world record bike has an alu frame.
http://weightweenies.starbike.com/articles.php?category=roadbikes
btw: if you are not a pro, a lighter frame won't do you any good. there are
many other things to consider when |
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h*****a
发帖数: 1992 | 47 都不是啥好店, 就是便宜.
昨天在Campbell, CA那个Performance的店, 排在我后面一女生推着一辆Fuji Absolute
2.0 checkout. 铝架+碳叉+Deore, 才$499. 20% off再有10%的performance point,
加了税算下来不到$400, 真的很便宜.
store. |
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h*****a
发帖数: 1992 | 48 我的Fuji是铝架+carbon fork+carbon stay，20 lb左右，乱七八糟的零件很多，基本
上是Ultegra+Rival的level 吧。这个车基本周末出去骑，有一年多了，差不多有2000
mile。总体感觉其实还可以，一个能感觉出来不太好的地方是那个车架+SRAM Rival的
compact crank+BB好像很软，站起来骑的时候能感觉到形变。另外那个fuji是56cm的，
top tube对我来说长了点，爬着有点难受，换了90mm的stem，把坐位前推才感觉好点。
照我这个情况，一个个的换零件好像太麻烦。如果我能把我现在这个Fuji 7,8百刀卖了
, 换那个RT800回来也就才$2300的样子，暂时不太需要换什么零件了吧?
3.
1.
carbon
put
can
nice |
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b******n
发帖数: 1269 | 49 所谓停产了，其实没有什么大不了的。铝合金车架是成熟产品。又不是因为产品质量问
题。
佳能得的铝架做得相当不错（气象专家要发飚了）。 |
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b******n
发帖数: 1269 | 50 有几个想法：
1。其实不怪材料，市场需要一个高端的媒介。10年前的高端铝架也3000美金了。就好
像中国最近把字画炒到梵高毕加索的价格之后，大家开始炒鸟笼子和奇石了。市场需要
高端的东西。
2。人在某些年龄段对事物接受能力最强，所以过了这个时段，新东西就不原意接受了
。国内一帮老头子收集解放前的老凤头，也上万块，每天擦得锃亮。
3。注意标题是“......最好”,不是“......也挺好”。 Recreational riders don't
need the best, but if they WANT the best and can afford it, so be it. |
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