Car Racks and Carbon Fiber?

I like Thule's language in the produce description. Rather than

"fragile frame" they use "sensitive frame." You wouldn't want to hurt a

sensitive frame's feelings.

.....

EEEYEAH ! that's exactly what I was trying to report.

Like you know Lance is sensitive.

On Monday, June 3, 2013 4:44:24 PM UTC-4, Jay Beattie wrote:
On Jun 3, 11:21*am, sms wrote:

On 6/3/2013 10:28 AM, thirty-six wrote:



Columbus have a professionals model, available for general purchase,

in which the forks are wrapped with a metal mesh. *These are not the

same forks as most amateurs use. *The extra mesh gives a skin to the

forks of greater energy density and makes them stronger and tougher in

use * I expect other manufacturers who supply (a) professional team(s)

do the same. * There's a little more weight on the front, but unless

you are a nutcase, that makes no difference on the road.



When you're riding the bike, the forces on the dropouts are very

different than when the bike is clamped into a rack. When the fork is

locked into a rack it's not the same as riding with a wheel locked into

the dropouts. As one person wrote: "there is nothing to give way,

everything it too secure, so all the torque is focused on that spot."

When you're riding, most of the torque is up into the dropouts, the

wheels are angled during banking turns. On a vehicle you have crosswinds

as well as air flow from the movement of the vehicle.



The professional models of forks may help, but those bicycles are

replaced at short intervals anyway. With carbon dropouts I'd be

extremely wary of using a fork mount rack. Of course there are other

reasons to not transport a CF bike on top of a car. Hitch mount racks

behind the car are better for CF as the bike is shielded by the car body.



Look at the support vehicles for the Amgen Tour and how nearly all the

bicycles are being carried on the roof:

https://www.youtube.com/watch?v=XPjApFZzgE0. And they're not driving

at 80mph either. The bottom line is that you don't want to clamp the

dropouts, especially on a CF fork, but you don't want to clamp a CF

frame either, so you hold the bicycle upright by the wheel. You can also

support it by the frame without clamping it.



It looks like the support cars are using a mix of fork clamp and DT or

wheel clamp racks. Those bikes in the wheel or DT clamp racks are

positioned at the ends of the rack, probably for quick change, and the

fork clamped bikes are on the inside of the rack. At least that is the

way it looks to me. Cars with one or two bikes use a DT or wheel clamp

-- again, probably for faster deployment. You can't assume that a rack

type is chosen due to fear over CF failure, at least not without

talking to the person who made the choice.



-- Jay Beattie.

.....

Andy would know if possible to preset the torques there, experimentally with vast experience

On Jun 4, 2:06*pm, sms wrote:
On 6/4/2013 1:09 AM, wrote:

sms, I would, reluctantly, beg to differ. *Any stress on the fork sliders and seals, or the headset, comes from acceleration, deceleration and wind. *All of those forces will act primarily on the heaviest part of the bicycle. *Thus, if you clamp the fork dropouts you reduce the torque on the headset because of a reduction in leverage - less so longitudinally, because the wheel can move very slightly, but laterally appreciably so. *Thus, a fork dropout clamp is likely to be better for your bicycle IF you can't clamp the frame.

I use one of thesehttp://www.thule.com/en/gb/products/carriers-and-racks/bike-carriers/...

Admittedly, I have 36mm forks, 20mm axle and dual clamps - so the forks are one of the strongest (and heaviest) components on the bike - but this setup is very secure and puts far less stress on bearings than alternatives (I can't clamp the frame as it's CF).

I like Thule's language in the produce description. Rather than
"fragile frame" they use "sensitive frame." You wouldn't want to hurt a
sensitive frame's feelings.

it is not a technical report but sales blurb, and the buyer with a
sensitive frame should not be racing, riding on public roads or over
rough terrain. The rider who also believes not only himself but also
his bicycle has a sensitive frame may well be satisfied with that mess
of words. I say get a steel framed bike and if you haven't bent or
broken it, you're not trying hard enough. Bending derailleur hanger
doesn't count, nor does bending a poorly-built wheel, denting forks or
stays. Your forks should fail before a good wheel. Your frame should
fail before your forks. It should be a good crash that bends your
main triangle.