I can only speak for the one inch "Star Carbon" made by Colnogo. It weighs a little over 400 grams and it has a real solid feel. I think the weakness in carbon forks would not be in the steerer but in the stanchions. A hard whack to the sides could crack them. In a head-on collision I also think the stanchion would break before the steerer. If you never crash your all carbon fork it should last a very long time.
russellseaton1@yahoo.com wrote:> The expansion plug, star nut, top cap, is only used to> initially adjust the headset.
I thought that the expansion plug unlike a star nut is also there to help resist compression forces when you tighten the stem around the steerer? I've also seen really elongated top caps that extend several centimeters down into the steerer (Cannondales come with a cap like this), which I assume are intended to do the same?
Tom Sherman 24 February 2005 09:19:44 [ permanent link ]
John Crankshaw wrote:
I'm thinking of replacing my carbon fork with steel steerer (over 700 grams)> with an all-carbon fork (less than 400 grams). It's 1" threadless in a 16 cm> head tube. The bike is a Univega steel frame.
[Pedant alert]
Where can one get a fork made from no element but carbon?
Zog The Undeniable 26 February 2005 22:21:49 [ permanent link ]
John Crankshaw wrote:
I'm thinking of replacing my carbon fork with steel steerer (over 700 grams)> with an all-carbon fork (less than 400 grams). It's 1" threadless in a 16 cm> head tube. The bike is a Univega steel frame.>
I'm 170# and a strong rider (for a 58 yr old).
Strong enough yes, stiff enough possibly not. If you go for a metal steerer and ride the bike in winter, some people recommend a steel steerer rather than an alloy one. The steel one will also be stiffer.
I'm thinking of replacing my carbon fork with steel steerer (over 700 >> grams)>> with an all-carbon fork (less than 400 grams). It's 1" threadless in a >> 16 cm>> head tube. The bike is a Univega steel frame.>>
I'm 170# and a strong rider (for a 58 yr old).>
Strong enough yes, stiff enough possibly not. If you go for a metal > steerer and ride the bike in winter, some people recommend a steel > steerer rather than an alloy one. The steel one will also be stiffer.
I say bugleoil. We sell many 1 inch Reynolds Ouzo Pro, the 'standard' for most Calfees and many others-No problem for a 'strong' rider.
I have a 1" all carbon Look hsc-3 with a 1 cm spacer and a 1" 120mm stem. I'm no clydesdale at 150lbs, but I race hard and sprint hard. Stiffness is not an issue, and I've never touched the headset or the stem in the 3 years I've used the fork. 2 tips: first, you shouldnt have more than 1 cm of spacers (this is what Look recommends) and don't use a stem that needs a shim. Get a proper stem, not a BS 1-1/8 jury rig thing with a shim. If you need more than 1 cm of spacers, use another fork with an Al or steel steer tube, or get a frame that fits you properly with a longer headtube. You can find a decent 1" stem really cheap at icyclesusa.com
I agree with Peter, there are many carbon fork mfrs who make a 1" carbon steerer tube fork like Reynolds, True Temper, Look, Mizuno, and Wound up, to name a few.
However, I did get an email warning from an "engineer" at Easton telling me: "If you weight 190 lb, I recommend you do NOT use a 1" carbon steer tube. The strength/stiffness of a steer tube is proportional to the fourth power of the steer tube OD. That is why 1-1/8" steer tubes have replaced the 1" steer tube."
I disagreed with him. I believe 1-1/8" forks are a marketing scheme used to help mfrs "standardize" the number of forks they need for production purposes. I just can't see that extra 1/8" of an inch stiffening things up that much....
Josh McClure wrote:> When the Alpha Q Sub 3 was being released I had a customer (195 lbs.)> who purchased one and subsequently broke it in less than a month.> That being said, I like the Alpha Q design and I think that it is a> fluke. My customer hit a pot hole and the steerer broke away from the> fork legs.
So, was this True Temper Alpha Q or the original Alpha Q? My original Alpha Q had the titanium steertube come loose from the crown junction. No catastrophic failure, fortunately. TT replaced it, but it is sitting in the garage waiting for me to decide if I would be happier having someone build me a steel fork. Summer's coming; I need to decide. Any suggestions as to a possible builder?
This was one of the first Sub 3's. My customer actually lived out in the Bay area so he went over to the Korean gentleman who either owned Alpha Q at the time, or was the manager of operations or something. and actually got the owner to give him one of the first ones that were produced. This he subsequently broke and got replaced by Alpha Q. which he has not had any problems with to my knowledge.
As an addendum to my previous post, I ride a Waterford with a 1" steerer and the fork is a Look HSC 3 I somehow managed to omit those details in my earlier post.
Squid-in-Training Phil 17 March 2005 01:25:46 [ permanent link ]
bfd wrote:> I agree with Peter, there are many carbon fork mfrs who make a 1"> carbon steerer tube fork like Reynolds, True Temper, Look, Mizuno, and> Wound up, to name a few.>
However, I did get an email warning from an "engineer" at Easton> telling me: "If you weight 190 lb, I recommend you do NOT use a 1"> carbon steer tube. The strength/stiffness of a steer tube is> proportional to the fourth power of the steer tube OD. That is why> 1-1/8" steer tubes have replaced the 1" steer tube.">
I disagreed with him. I believe 1-1/8" forks are a marketing scheme> used to help mfrs "standardize" the number of forks they need for> production purposes. I just can't see that extra 1/8" of an inch> stiffening things up that much....
I'm inclined to believe him. I believe it has something to do with the moment of inertia of a cylinder.
In this case, Ix = Iy = 1/4*pi*r^4, and for a tube, I think you just subtract the inner "void," yielding 1/4*pi*(Router-Rinner)^4.
Here is a picture from my mechanics of materials textbook:
David L. Johnson 17 March 2005 02:36:54 [ permanent link ]
On Wed, 16 Mar 2005 21:25:46 +0000, Phil, Squid-in-Training wrote:
In this case, Ix = Iy = 1/4*pi*r^4, and for a tube, I think you just > subtract the inner "void," yielding 1/4*pi*(Router-Rinner)^4.
Well, yes, the moment of inertia about the axis of the cylinder will be proportional to r^4 for a solid cylinder, but you subtract the inner stuff after the power, not before, so it would be (Router)^4 - (Rinner)^4. Changing from 1 1/8 to 1 would be a reduction by (8/9)^4 =62.4%.
On the other hand, why the heck would that be relevant? The twisting force would be a more relevant quantity, as would the cross-sectional area, particularly at the crown. Both of these quantities vary roughly linearly with the radius, for a given thickness of material, so the difference would be (8/9)^1 = 89% going from 1 1/8 to 1.
--
David L. Johnson
__o | A mathematician is a machine for turning coffee into theorems. _`\(,_ | -- Paul Erdos (_)/ (_) |
In this case, Ix = Iy = 1/4*pi*r^4, and for a tube, I think you>> just subtract the inner "void," yielding 1/4*pi*(Router-Rinner)^4.
Well, yes, the moment of inertia about the axis of the cylinder will> be proportional to r^4 for a solid cylinder, but you subtract the> inner stuff after the power, not before, so it would be (Router)^4 -> (Rinner)^4. Changing from 1 1/8 to 1 would be a reduction by> (8/9)^4 =62.4%.
On the other hand, why the heck would that be relevant? The> twisting force would be a more relevant quantity, as would the> cross-sectional area, particularly at the crown. Both of these> quantities vary roughly linearly with the radius, for a given> thickness of material, so the difference would be (8/9)^1 = 89%> going from 1 1/8 to 1.
A steertube supports no significant torque but is round for other reasons such as rotational bearings and adjustable bar stem attachment. More important is its bending strength, and that primarily fore and aft of the direction of travel. That strength goes with the third power of diameter and that subtracts as in the example above.
On Wed, 16 Mar 2005 21:25:46 GMT, "Phil, Squid-in-Training" <phil_leeIHEARTBASHGUARDS@hotmail.com> wrote:
bfd wrote:>> I agree with Peter, there are many carbon fork mfrs who make a 1">> carbon steerer tube fork like Reynolds, True Temper, Look, Mizuno, and>> Wound up, to name a few.>>
However, I did get an email warning from an "engineer" at Easton>> telling me: "If you weight 190 lb, I recommend you do NOT use a 1">> carbon steer tube. The strength/stiffness of a steer tube is>> proportional to the fourth power of the steer tube OD. That is why>> 1-1/8" steer tubes have replaced the 1" steer tube.">>
I disagreed with him. I believe 1-1/8" forks are a marketing scheme>> used to help mfrs "standardize" the number of forks they need for>> production purposes. I just can't see that extra 1/8" of an inch>> stiffening things up that much....>
I'm inclined to believe him. I believe it has something to do with the >moment of inertia of a cylinder.>
In this case, Ix = Iy = 1/4*pi*r^4, and for a tube, I think you just >subtract the inner "void," yielding 1/4*pi*(Router-Rinner)^4.>
Here is a picture from my mechanics of materials textbook:>
Squid-in-Training Phil 17 March 2005 06:31:57 [ permanent link ]
carlfogel@comcast.net wrote:> On Wed, 16 Mar 2005 21:25:46 GMT, "Phil, Squid-in-Training"> <phil_leeIHEARTBASHGUARDS@hotmail.com> wrote:>
bfd wrote:>>> I agree with Peter, there are many carbon fork mfrs who make a 1">>> carbon steerer tube fork like Reynolds, True Temper, Look, Mizuno,>>> and Wound up, to name a few.>>>
However, I did get an email warning from an "engineer" at Easton>>> telling me: "If you weight 190 lb, I recommend you do NOT use a 1">>> carbon steer tube. The strength/stiffness of a steer tube is>>> proportional to the fourth power of the steer tube OD. That is why>>> 1-1/8" steer tubes have replaced the 1" steer tube.">>>
I disagreed with him. I believe 1-1/8" forks are a marketing scheme>>> used to help mfrs "standardize" the number of forks they need for>>> production purposes. I just can't see that extra 1/8" of an inch>>> stiffening things up that much....>>
I'm inclined to believe him. I believe it has something to do with>> the moment of inertia of a cylinder.>>
In this case, Ix = Iy = 1/4*pi*r^4, and for a tube, I think you just>> subtract the inner "void," yielding 1/4*pi*(Router-Rinner)^4.>>
Here is a picture from my mechanics of materials textbook:>>
On Wed, 16 Mar 2005 21:25:46 GMT, "Phil, Squid-in-Training">><phil_leeIHEARTBASHGUARDS@hotmail.com> wrote:>>
bfd wrote:>>>
I agree with Peter, there are many carbon fork mfrs who make a 1">>>>carbon steerer tube fork like Reynolds, True Temper, Look, Mizuno,>>>>and Wound up, to name a few.>>>>
However, I did get an email warning from an "engineer" at Easton>>>>telling me: "If you weight 190 lb, I recommend you do NOT use a 1">>>>carbon steer tube. The strength/stiffness of a steer tube is>>>>proportional to the fourth power of the steer tube OD. That is why>>>>1-1/8" steer tubes have replaced the 1" steer tube.">>>>
I disagreed with him. I believe 1-1/8" forks are a marketing scheme>>>>used to help mfrs "standardize" the number of forks they need for>>>>production purposes. I just can't see that extra 1/8" of an inch>>>>stiffening things up that much....>>>
I'm inclined to believe him. I believe it has something to do with>>>the moment of inertia of a cylinder.>>>
In this case, Ix = Iy = 1/4*pi*r^4, and for a tube, I think you just>>>subtract the inner "void," yielding 1/4*pi*(Router-Rinner)^4.>>>
Here is a picture from my mechanics of materials textbook:>>>
On Thu, 17 Mar 2005 02:31:57 GMT, "Phil, Squid-in-Training" <phil_leeIHEARTBASHGUARDS@hotmail.com> wrote:
carlfogel@comcast.net wrote:>> On Wed, 16 Mar 2005 21:25:46 GMT, "Phil, Squid-in-Training">> <phil_leeIHEARTBASHGUARDS@hotmail.com> wrote:>>
bfd wrote:>>>> I agree with Peter, there are many carbon fork mfrs who make a 1">>>> carbon steerer tube fork like Reynolds, True Temper, Look, Mizuno,>>>> and Wound up, to name a few.>>>>
However, I did get an email warning from an "engineer" at Easton>>>> telling me: "If you weight 190 lb, I recommend you do NOT use a 1">>>> carbon steer tube. The strength/stiffness of a steer tube is>>>> proportional to the fourth power of the steer tube OD. That is why>>>> 1-1/8" steer tubes have replaced the 1" steer tube.">>>>
I disagreed with him. I believe 1-1/8" forks are a marketing scheme>>>> used to help mfrs "standardize" the number of forks they need for>>>> production purposes. I just can't see that extra 1/8" of an inch>>>> stiffening things up that much....>>>
I'm inclined to believe him. I believe it has something to do with>>> the moment of inertia of a cylinder.>>>
In this case, Ix = Iy = 1/4*pi*r^4, and for a tube, I think you just>>> subtract the inner "void," yielding 1/4*pi*(Router-Rinner)^4.>>>
Here is a picture from my mechanics of materials textbook:>>>
