T*****u
发帖数: 7103 | 1 上次听一个小二说出了重量，碳架更加减震。铝架车骑多了对脊柱不好。 |
h******2
发帖数: 1498 | 2 小二的首要任务是赚钱，而不是提供信息。
如果钱不是问题，就买碳架。否则就买铝架。
一开始最重要的是先骑上几千mile，否则再多research也是纸上谈兵。 |
w********6
发帖数: 12977 | 3 我也骑车几千英里了，一直是BD的铝架子车，还是啥也不知道，因为没有比较啊。
另外还有碳铝结合的，钛合金的frame，铁的。。。
【在 h******2 的大作中提到】
: 小二的首要任务是赚钱，而不是提供信息。
: 如果钱不是问题，就买碳架。否则就买铝架。
: 一开始最重要的是先骑上几千mile，否则再多research也是纸上谈兵。
|
h******2
发帖数: 1498 | 4 现在让你骑钢架或者碳架，你就知道区别了。
【在 w********6 的大作中提到】
: 我也骑车几千英里了，一直是BD的铝架子车，还是啥也不知道，因为没有比较啊。
: 另外还有碳铝结合的，钛合金的frame，铁的。。。
|
w********6
发帖数: 12977 | 5 问题是没有机会，也许去店里试一下。
【在 h******2 的大作中提到】
: 现在让你骑钢架或者碳架，你就知道区别了。
|
x********i
发帖数: 115 | 6 别老听那些胡扯说骑车对身体各种影响，业余爱好者只要不出车祸随你折腾，等你骑出
颈椎毛病的时候你就可以转职业了
【在 T*****u 的大作中提到】
: 上次听一个小二说出了重量，碳架更加减震。铝架车骑多了对脊柱不好。
|
i**********g
发帖数: 159 | 7 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 |
w******x
发帖数: 4396 | 8 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
【在 i**********g 的大作中提到】
: 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
|
h******2
发帖数: 1498 | 9 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? |
V*****n
发帖数: 893 | |
|
|
w********6
发帖数: 12977 | 11 In last issue of cyclist, the first dream bike introduced is ti one, weigh
an insane 13 lbs |
V*****n
发帖数: 893 | |
w******x
发帖数: 4396 | 13 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
【在 h******2 的大作中提到】
: 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?
|
w******x
发帖数: 4396 | 14 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.
【在 V*****n 的大作中提到】
: http://www.sheldonbrown.com/frame-materials.html
|
V*****n
发帖数: 893 | 15 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
【在 w******x 的大作中提到】
: 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.
|
V*****n
发帖数: 893 | 16 this doesn't break down the tensile vs. torsional, but is a good illustrate
nonetheless.
http://www.litespeed.com/current/tech_mat.aspx
load
【在 w******x 的大作中提到】
: 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
|
i**********g
发帖数: 159 | 17 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
【在 w******x 的大作中提到】
: 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
|
h******2
发帖数: 1498 | 18 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? |
w******x
发帖数: 4396 | 19 "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
【在 i**********g 的大作中提到】
: 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
|
i**********g
发帖数: 159 | 20 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.
【在 w******x 的大作中提到】
: "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
|
|
|
V*****n
发帖数: 893 | 21 then, you should do some reading on the Mavic R-sys wheels.
only.
in
【在 i**********g 的大作中提到】
: 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.
|
J********e
发帖数: 2284 | 22 各位大牛谈了很多有用的冬冬，我最感兴趣的是：我的铝架，一般而言上了多少
mileage就要小心，上了多少mileage就要考虑扔掉了。怎么观察从而发现failure的征
兆？ |
h******2
发帖数: 1498 | 23 你的铝架不拿来race的话可以骑到你不想骑车：）
【在 J********e 的大作中提到】
: 各位大牛谈了很多有用的冬冬，我最感兴趣的是：我的铝架，一般而言上了多少
: mileage就要小心，上了多少mileage就要考虑扔掉了。怎么观察从而发现failure的征
: 兆？
|
w******x
发帖数: 4396 | 24 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
【在 J********e 的大作中提到】
: 各位大牛谈了很多有用的冬冬，我最感兴趣的是：我的铝架，一般而言上了多少
: mileage就要小心，上了多少mileage就要考虑扔掉了。怎么观察从而发现failure的征
: 兆？
|
