Fork-mount fears

I've got a Yakima Viper roof rack which is a fork-mount type thing. My
bike is pretty light compared to my old hybrid (20 vs 30+ lbs) but I
still wonder how safe it is having a carbon-forked (or ANY-forked) bike
held onto the roof by its fork dropouts. Isn't there an *extreme*
amount of torque applied there on any cornering, crosswinds, etc? Yet
I never hear about damage unless the poster is talking about driving
into an obstruction or dropping the bike sideways before tightening the
skewer fully. Otherwise, no damage reports.

Why is this? Am I overestimating the stresses experienced or am I
underestimating the strength of the fork? Or both? I just want to
feel like I'm not abusing my bike by using this rack.

Had all of ours on the RR for years and no CF fork failures to date.
Drove all over TX & OK with them @ 55mph+. We even eliminated the
lawyer lips on one of them [mine:-)] and never had one come loose or
cause a problem.

I have however seen a bike on a RR vs Garage that did not fare well for
the fork but the rack did fine. Once you get used to them on there,
it's all good. Sort of like towing a trailer the first couple of
times....

I'm glad to hear you haven't had any carbon fork failures from the rack
(sorry, I cannot figure out how to auto-quote your post, so I'm
paraphrasing you).. It's just that I got the willies seeing my bike
held on by nothing more than the front dropouts (which are WAY below
the bike's center of gravity for being pushed by wind, cornering of the
car, etc..). Oh, I suppose the rear tire is technically supported as
well, but that doesn't comfort me for some reason.

But if folks keep telling me they've never hurt their bike this way
(short of the usual dumb disasters), then I'll quit worrying.

In article . com,
wrote:

I'm glad to hear you haven't had any carbon fork failures from the rack
(sorry, I cannot figure out how to auto-quote your post, so I'm
paraphrasing you).. It's just that I got the willies seeing my bike
held on by nothing more than the front dropouts (which are WAY below
the bike's center of gravity for being pushed by wind, cornering of the
car, etc..). Oh, I suppose the rear tire is technically supported as
well, but that doesn't comfort me for some reason.

But if folks keep telling me they've never hurt their bike this way
(short of the usual dumb disasters), then I'll quit worrying.

Just to make you feel better, consider the stresses that the front fork
experiences when you are actually riding, and going around a tight curve
at 20+ miles per hour. The *rider* can be 8 to 10 times the weight of the
bicycle, so holding an *unloaded* bicycle by it's front fork should be no
sweat for the bicycle's structure.

--- Joe

In article . com,
wrote:

I'm glad to hear you haven't had any carbon fork failures from the rack
(sorry, I cannot figure out how to auto-quote your post, so I'm
paraphrasing you).. It's just that I got the willies seeing my bike
held on by nothing more than the front dropouts (which are WAY below
the bike's center of gravity for being pushed by wind, cornering of the
car, etc..). Oh, I suppose the rear tire is technically supported as
well, but that doesn't comfort me for some reason.

But if folks keep telling me they've never hurt their bike this way
(short of the usual dumb disasters), then I'll quit worrying.

Just to make you feel better, consider the stresses that the front fork
experiences when you are actually riding, and going around a tight curve
at 20+ miles per hour. The *rider* can be 8 to 10 times the weight of the
bicycle, so holding an *unloaded* bicycle by it's front fork should be no
sweat for the bicycle's structure.

--- Joe

"Joe" wrote: (clip) consider the stresses that the front fork experiences
when you are actually riding, and going around a tight curve at 20+ miles
per hour. (clip)
^^^^^^^^^^^^^^^
Joe, the weight and cornering force combine to form a resultant force that
goes down through the front and rear wheels to the road. The bike and rider
lean to make this happen. This force is not trying to dislodge the skewer
from the cropouts.

On the other hand, Burnedtechie's fears are not justified by the experience
of the thousands of bikers who transport their bikes for thousands of miles
supported by the front fork. If this were a real problem, then we would all
be worrying about it.

On Sun, 28 May 2006 14:32:12 -0700, burnedtechie wrote:

I've got a Yakima Viper roof rack which is a fork-mount type thing. My
bike is pretty light compared to my old hybrid (20 vs 30+ lbs) but I
still wonder how safe it is having a carbon-forked (or ANY-forked) bike
held onto the roof by its fork dropouts. Isn't there an *extreme*
amount of torque applied there on any cornering, crosswinds, etc? Yet
I never hear about damage unless the poster is talking about driving
into an obstruction or dropping the bike sideways before tightening the
skewer fully. Otherwise, no damage reports.

Why is this? Am I overestimating the stresses experienced or am I
underestimating the strength of the fork? Or both?

Yep. The weight of the bike is nothing compared to the weight of the
rider, and the fork holds up pretty well under the rider's weight,
including cross-winds, turns, and potholes that knock kinks into the
wheels.

I've been using this same rack for years. So have many others. Frankly,
I prefer fork mounts to those that clamp onto the downtube.

--

David L. Johnson

__o | Arguing with an engineer is like mud wrestling with a pig... You
_`\(,_ | soon find out the pig likes it!
(_)/ (_) |

In article ,
"Leo Lichtman" wrote:

"Joe" wrote: (clip) consider the stresses that the front fork experiences
when you are actually riding, and going around a tight curve at 20+ miles
per hour. (clip)
^^^^^^^^^^^^^^^
Joe, the weight and cornering force combine to form a resultant force that
goes down through the front and rear wheels to the road. The bike and rider
lean to make this happen. This force is not trying to dislodge the skewer
from the cropouts.

On the other hand, Burnedtechie's fears are not justified by the experience
of the thousands of bikers who transport their bikes for thousands of miles
supported by the front fork. If this were a real problem, then we would all
be worrying about it.

Leo,

The OP was concerned with " underestimating the strength of the fork". My
post quite adequately covered that point.

--- Joe

"Joe" wrote: The OP was concerned with " underestimating the strength of
the fork". My post quite adequately covered that point.
^^^^^^^^^^^^^^^^^
Quite right, if you refer to his first post. In his second post, he says,
"It's just that I got the willies seeing my bike held on by nothing more
than the front dropouts," which leads me to think he is also concerned about
the skewer security. You were replying to something he actually he actually
said, and I shifted the emphasis to something ELSE he seemed to be saying.
I apologize.

I've been using this same rack for years. So have many others. Frankly,
I prefer fork mounts to those that clamp onto the downtube.

On the other hand, we've replaced a fair number of forks that were damaged
by roof racks that clamp to the fork's dropouts. Not damaged during actual
use, mind you, but rather while someone was trying to put the bike on it,
and before being able to secure the front Q/R, the bike managed to start
falling to the side, quickly (and severely) bending one of the dropouts.
Filing the dropout tabs can help in this regard, since it eliminates the
need to readjust the Q/R each time it's used (although later designs of
fork-mount roof racks have Q/R designs that no longer require readjustment
when used with lawyer-lip'd dropout... and yet people still manage to mangle
them).

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"David L. Johnson" wrote in message
news
On Sun, 28 May 2006 14:32:12 -0700, burnedtechie wrote:

I've got a Yakima Viper roof rack which is a fork-mount type thing. My
bike is pretty light compared to my old hybrid (20 vs 30+ lbs) but I
still wonder how safe it is having a carbon-forked (or ANY-forked) bike
held onto the roof by its fork dropouts. Isn't there an *extreme*
amount of torque applied there on any cornering, crosswinds, etc? Yet
I never hear about damage unless the poster is talking about driving
into an obstruction or dropping the bike sideways before tightening the
skewer fully. Otherwise, no damage reports.

Why is this? Am I overestimating the stresses experienced or am I
underestimating the strength of the fork? Or both?

Yep. The weight of the bike is nothing compared to the weight of the
rider, and the fork holds up pretty well under the rider's weight,
including cross-winds, turns, and potholes that knock kinks into the
wheels.

I've been using this same rack for years. So have many others. Frankly,
I prefer fork mounts to those that clamp onto the downtube.

--

David L. Johnson

__o | Arguing with an engineer is like mud wrestling with a pig... You
_`\(,_ | soon find out the pig likes it!
(_)/ (_) |