Thule roof rack and carbon dropouts?



D

David

Guest
Asking for a friend, so sorry if I don't have all the details, but he
has a Look frame and fork. The fork has carbon dropouts. He has a
Thule roof rack (unsure of the model) but as he tells me, the skewer/
dropout clamp flanges are too big in diameter and don't sit against
the dropouts properly, plus, should he use this system with a carbon
fork with carbon dropouts?

Comments? Does Thule (or someone else) make another clamp that would
work? Should he not use tis type of "dropout grabbing" rack with
carbon droputs? (Crushing the dropout for example)

Thanks....
 
L

Leo Lichtman

Guest
"David" wrote (clip) the skewer/
> dropout clamp flanges are too big in diameter and don't sit against
> the dropouts properly,(clip)

^^^^^^^^^^^^^^^^^^^^^
If he can get skewers long enough, he could insert spacersthat are small
enough in diameter to seat properly against the flat part of the dropouts.

He could change to the type of support where you leave the front wheel on,
and hold the frame. That's how I would do it if the extra money is not an
obstacle.
 
D

David

Guest
Thanks, Leo, I did not explain clearly. The flanges are too big in
diameter and don't sit flush against the outer side of the dropout
because of those little tabs. I wonder if there is any replacement
flange or some thurd party thingie he can use.

Do you think in general this type of dropout holder is a bad thing for
carbon dropouts? With all of the bouncing of a bike on a roof rack
and the odd center of gravity of the bke. What do you think?




On Jan 17, 11:37 am, "Leo Lichtman" <[email protected]>
wrote:
> "David" wrote (clip) the skewer/> dropout clamp flanges are too big in diameter and don't sit against
> > the dropouts properly,(clip)

>
> ^^^^^^^^^^^^^^^^^^^^^
> If he can get skewers long enough, he could insert spacersthat are small
> enough in diameter to seat properly against the flat part of the dropouts.
>
> He could change to the type of support where you leave the front wheel on,
> and hold the frame. That's how I would do it if the extra money is not an
> obstacle.
 
M

Mike Jacoubowsky

Guest
> Asking for a friend, so sorry if I don't have all the details, but he
> has a Look frame and fork. The fork has carbon dropouts. He has a
> Thule roof rack (unsure of the model) but as he tells me, the skewer/
> dropout clamp flanges are too big in diameter and don't sit against
> the dropouts properly, plus, should he use this system with a carbon
> fork with carbon dropouts?
>
> Comments? Does Thule (or someone else) make another clamp that would
> work? Should he not use tis type of "dropout grabbing" rack with
> carbon droputs? (Crushing the dropout for example)
>
> Thanks....


I no longer feel comfortable with roof racks that clamp the front forks,
period. Particularly for road bikes. I've seen too many customers mangle a
dropout as they were trying to get the bike onto or off of the rack, and the
type of forces exerted on a dropout during transit on such a rack are not
forces a bike will ever see in normal use, and thus I find it very unlikely
they were designed to handle them. No matter how hard you corner, as long as
the wheel stays in place, there's simply no way to put much of a side load
onto a front wheel dropout. But clamp a bike to a roof rack and watch it
oscillate & buzz in a crosswind... it's just not something I feel
comfortable with.

Older steel forks are probably less of an issue, because we weren't
designing things for ultra light weight, and things tended to be overbuilt.
But modern forks generally don't have material where they don't need it, and
the strength and weakness of carbon is that you have complete control over
placement of the material... so an area presumed to have relatively low
stress may be built accordingly.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA


"David" <[email protected]> wrote in message
news:[email protected]m...
> Asking for a friend, so sorry if I don't have all the details, but he
> has a Look frame and fork. The fork has carbon dropouts. He has a
> Thule roof rack (unsure of the model) but as he tells me, the skewer/
> dropout clamp flanges are too big in diameter and don't sit against
> the dropouts properly, plus, should he use this system with a carbon
> fork with carbon dropouts?
>
> Comments? Does Thule (or someone else) make another clamp that would
> work? Should he not use tis type of "dropout grabbing" rack with
> carbon droputs? (Crushing the dropout for example)
>
> Thanks....
 
D

David

Guest
Mike; thanks! This is pretty much what I thought. my friend, an LBS
owner, who has been racing pro said it was not a big deal, but I still
was questioning it. Me? I hav a Ti frame and a Carbon and Ti, and I
use a top tube clamping hitch rack, an even with that I worry a little
with the stress on the top tube. (I keep the bike inside the vehicle
whenever possible - a lot less hassles ;-)

But your description is a much better than the one I provided the
friend in my original post and I'm going to send that off to him. I
suspect it's even more valid with carbon dropouts.

Thanks!

Dave



On Jan 17, 7:38 pm, "Mike Jacoubowsky" <[email protected]>
wrote:
> > Asking for a friend, so sorry if I don't have all the details, but he
> > has a Look frame and fork. The fork has carbon dropouts. He has a
> > Thule roof rack (unsure of the model) but as he tells me, the skewer/
> > dropout clamp flanges are too big in diameter and don't sit against
> > the dropouts properly, plus, should he use this system with a carbon
> > fork with carbon dropouts?

>
> > Comments? Does Thule (or someone else) make another clamp that would
> > work? Should he not use tis type of "dropout grabbing" rack with
> > carbon droputs? (Crushing the dropout for example)

>
> > Thanks....

>
> I no longer feel comfortable with roof racks that clamp the front forks,
> period. Particularly for road bikes. I've seen too many customers mangle a
> dropout as they were trying to get the bike onto or off of the rack, and the
> type of forces exerted on a dropout during transit on such a rack are not
> forces a bike will ever see in normal use, and thus I find it very unlikely
> they were designed to handle them. No matter how hard you corner, as long as
> the wheel stays in place, there's simply no way to put much of a side load
> onto a front wheel dropout. But clamp a bike to a roof rack and watch it
> oscillate & buzz in a crosswind... it's just not something I feel
> comfortable with.
>
> Older steel forks are probably less of an issue, because we weren't
> designing things for ultra light weight, and things tended to be overbuilt.
> But modern forks generally don't have material where they don't need it, and
> the strength and weakness of carbon is that you have complete control over
> placement of the material... so an area presumed to have relatively low
> stress may be built accordingly.
>
> --Mike Jacoubowsky
> Chain Reaction Bicycleswww.ChainReaction.com
> Redwood City & Los Altos, CA USA
>
> "David" <[email protected]> wrote in message
>
> news:[email protected]m...
>
> > Asking for a friend, so sorry if I don't have all the details, but he
> > has a Look frame and fork. The fork has carbon dropouts. He has a
> > Thule roof rack (unsure of the model) but as he tells me, the skewer/
> > dropout clamp flanges are too big in diameter and don't sit against
> > the dropouts properly, plus, should he use this system with a carbon
> > fork with carbon dropouts?

>
> > Comments? Does Thule (or someone else) make another clamp that would
> > work? Should he not use tis type of "dropout grabbing" rack with
> > carbon droputs? (Crushing the dropout for example)

>
> > Thanks....
 
S

SMS

Guest
David wrote:
> Asking for a friend, so sorry if I don't have all the details, but he
> has a Look frame and fork. The fork has carbon dropouts. He has a
> Thule roof rack (unsure of the model) but as he tells me, the skewer/
> dropout clamp flanges are too big in diameter and don't sit against
> the dropouts properly, plus, should he use this system with a carbon
> fork with carbon dropouts?
>
> Comments? Does Thule (or someone else) make another clamp that would
> work? Should he not use tis type of "dropout grabbing" rack with
> carbon droputs? (Crushing the dropout for example)


He should not use it.

With all the racks available that hold a bike with the two wheels on,
why are people still destroying their bicycles with the racks that clamp
the fork? Some of the damage I've seen to people's bikes from these
racks cost far more to repair than the cost of a proper Thule or Yakima
upright attachment. It's not just damage to the fork either (though
that's more and more common with non-steel forks). It's headset damage
as well. I've seen steel forks damaged by these racks as well when the
QR vibrates loose and the fork is being held by one drop out with the
other one up in the air.

When a bicycle is sitting on two wheels it may sway in the rack, but
it's not putting much stress on anything. Of course with a carbon frame
you have to be careful not to clamp the frame very hard.

Tell your friend to spend the money on a proper upright mount.
 
J

jim beam

Guest
Mike Jacoubowsky wrote:
>> Asking for a friend, so sorry if I don't have all the details, but he
>> has a Look frame and fork. The fork has carbon dropouts. He has a
>> Thule roof rack (unsure of the model) but as he tells me, the skewer/
>> dropout clamp flanges are too big in diameter and don't sit against
>> the dropouts properly, plus, should he use this system with a carbon
>> fork with carbon dropouts?
>>
>> Comments? Does Thule (or someone else) make another clamp that would
>> work? Should he not use tis type of "dropout grabbing" rack with
>> carbon droputs? (Crushing the dropout for example)
>>
>> Thanks....

>
> I no longer feel comfortable with roof racks that clamp the front forks,
> period.


couldn't agree more. bikes aren't built for 70+mph or cross winds on a
roof rack.


> Particularly for road bikes. I've seen too many customers mangle a
> dropout as they were trying to get the bike onto or off of the rack, and the
> type of forces exerted on a dropout during transit on such a rack are not
> forces a bike will ever see in normal use, and thus I find it very unlikely
> they were designed to handle them. No matter how hard you corner, as long as
> the wheel stays in place, there's simply no way to put much of a side load
> onto a front wheel dropout. But clamp a bike to a roof rack and watch it
> oscillate & buzz in a crosswind... it's just not something I feel
> comfortable with.
>
> Older steel forks are probably less of an issue, because we weren't
> designing things for ultra light weight, and things tended to be overbuilt.
> But modern forks generally don't have material where they don't need it, and
> the strength and weakness of carbon is that you have complete control over
> placement of the material... so an area presumed to have relatively low
> stress may be built accordingly.


indeed.

carry all bikes internally. if the car doesn't accommodate, change the car.


>
> --Mike Jacoubowsky
> Chain Reaction Bicycles
> www.ChainReaction.com
> Redwood City & Los Altos, CA USA
>
>
> "David" <magicrev[email protected]> wrote in message
> news:[email protected]m...
>> Asking for a friend, so sorry if I don't have all the details, but he
>> has a Look frame and fork. The fork has carbon dropouts. He has a
>> Thule roof rack (unsure of the model) but as he tells me, the skewer/
>> dropout clamp flanges are too big in diameter and don't sit against
>> the dropouts properly, plus, should he use this system with a carbon
>> fork with carbon dropouts?
>>
>> Comments? Does Thule (or someone else) make another clamp that would
>> work? Should he not use tis type of "dropout grabbing" rack with
>> carbon droputs? (Crushing the dropout for example)
>>
>> Thanks....

>
>
 
B

Barry

Guest
> I no longer feel comfortable with roof racks that clamp the front forks,
> period. Particularly for road bikes. I've seen too many customers mangle a
> dropout as they were trying to get the bike onto or off of the rack ...


I saw this happen once when a gust of wind caught the bike as a friend took it
off the roof.
 
D

David

Guest
So again from the friend for whom I did the OP....

Thoughts about the Yakima High Roller? He does not have a hitch, and
inside is not a convenient option, and this one seems to distribute
the lateral stress by holding the front wheel, and also has a strap
around the frame, to distribute some of that stress that would have
been on the dropout. Or perhaps the King Cobra?

I thought about the Raptor, but Yakima says clamping a CF tube is a no-
no.

Other comments?

http://yakima.com/Product.aspx?id=13 King Cobra

http://yakima.com/Product.aspx?id=17 Raptor


Thanks again guys...

Dave


On Jan 17, 11:17 pm, "Barry" <[email protected]> wrote:
> > I no longer feel comfortable with roof racks that clamp the front forks,
> > period. Particularly for road bikes. I've seen too many customers mangle a
> > dropout as they were trying to get the bike onto or off of the rack ...

>
> I saw this happen once when a gust of wind caught the bike as a friend took it
> off the roof.
 
M

Matt O'Toole

Guest
On Thu, 17 Jan 2008 16:38:09 -0800, Mike Jacoubowsky wrote:

> I no longer feel comfortable with roof racks that clamp the front forks,
> period. Particularly for road bikes. I've seen too many customers mangle
> a dropout as they were trying to get the bike onto or off of the rack,
> and the type of forces exerted on a dropout during transit on such a
> rack are not forces a bike will ever see in normal use, and thus I find
> it very unlikely they were designed to handle them. No matter how hard
> you corner, as long as the wheel stays in place, there's simply no way
> to put much of a side load onto a front wheel dropout. But clamp a bike
> to a roof rack and watch it oscillate & buzz in a crosswind... it's just
> not something I feel comfortable with.
>
> Older steel forks are probably less of an issue, because we weren't
> designing things for ultra light weight, and things tended to be
> overbuilt. But modern forks generally don't have material where they
> don't need it, and the strength and weakness of carbon is that you have
> complete control over placement of the material... so an area presumed
> to have relatively low stress may be built accordingly.


Mike, I share your concern. I've often wondered about the sideways
jostling in roof racks, and fatigue in the dropouts. But if it were a
problem we'd have seen failures by now.

I can't imagine large bike companies not considering this in their
engineering.

The only problem I've seen is bent dropouts from bikes being tipped
sideways as they're going in and out of the rack. This is probably what
you've seen too. I think this has gotten worse as cars have become trucks
and gotten taller, making it harder for people to reach the roof rack
safely when mounting/dismounting their bikes.

Once the bike is in the rack and secured though, it's probably OK.

Matt O.
 
M

Michael Press

Guest
In article <[email protected]>,
Matt O'Toole <[email protected]> wrote:

> On Thu, 17 Jan 2008 16:38:09 -0800, Mike Jacoubowsky wrote:
>
> > I no longer feel comfortable with roof racks that clamp the front forks,
> > period. Particularly for road bikes. I've seen too many customers mangle
> > a dropout as they were trying to get the bike onto or off of the rack,
> > and the type of forces exerted on a dropout during transit on such a
> > rack are not forces a bike will ever see in normal use, and thus I find
> > it very unlikely they were designed to handle them. No matter how hard
> > you corner, as long as the wheel stays in place, there's simply no way
> > to put much of a side load onto a front wheel dropout. But clamp a bike
> > to a roof rack and watch it oscillate & buzz in a crosswind... it's just
> > not something I feel comfortable with.
> >
> > Older steel forks are probably less of an issue, because we weren't
> > designing things for ultra light weight, and things tended to be
> > overbuilt. But modern forks generally don't have material where they
> > don't need it, and the strength and weakness of carbon is that you have
> > complete control over placement of the material... so an area presumed
> > to have relatively low stress may be built accordingly.

>
> Mike, I share your concern. I've often wondered about the sideways
> jostling in roof racks, and fatigue in the dropouts. But if it were a
> problem we'd have seen failures by now.


Failures are exactly what Mike is reporting. He quantified with `many.'

--
Michael Press
 
M

Mike Jacoubowsky

Guest
>> Older steel forks are probably less of an issue, because we weren't
>> designing things for ultra light weight, and things tended to be
>> overbuilt. But modern forks generally don't have material where they
>> don't need it, and the strength and weakness of carbon is that you have
>> complete control over placement of the material... so an area presumed
>> to have relatively low stress may be built accordingly.

>
> Mike, I share your concern. I've often wondered about the sideways
> jostling in roof racks, and fatigue in the dropouts. But if it were a
> problem we'd have seen failures by now.


But we do. We see a number of disbond failures where the dropout has
separated from the fork blades (on bonded aluminum or carbon forks). This
happens very rarely with bikes not used on roof racks. I've not kept track
of it, and perhaps should have, but my guess/estimate is that probably
greater than half of the failed disbonded dropouts we've seen have been from
bikes used on roof racks, which is a hugely-greater percent than the number
of bikes transported that way.

> I can't imagine large bike companies not considering this in their
> engineering.


It's not just the engineers dealing with this, it's also the lawyers. Funny
thing, those legal issues. Trek, for example, won't list a "maximum" rider
weight for a product for two reasons. First, your mileage may vary, and they
try to build products strong enough for any reasonable use. But there's also
this weird thing going on that says don't list a max rider weight because
that opens you up liabilities if something happens with a lighter rider
(regardless of how the product might have been abused).

How does this tie in to roof racks? Simple. A roof rack isn't considered
normal use of a bicycle. If you design something to specifically hold up to
such use (and somebody finds out about it), and there's a failure... bad
news for the manufacturer.

> The only problem I've seen is bent dropouts from bikes being tipped
> sideways as they're going in and out of the rack. This is probably what
> you've seen too. I think this has gotten worse as cars have become trucks
> and gotten taller, making it harder for people to reach the roof rack
> safely when mounting/dismounting their bikes.
>
> Once the bike is in the rack and secured though, it's probably OK.


Looking up at bikes strongly vibrating in the wind (on a roof rack), it just
doesn't seem like "it's probably OK." It's always made me nervous, and the
times I paid attention to it, the times when I used to use a roof rack that
fastened at the fork tips, those times were with a heavy steel bike, many
years ago. These days I actively tell customers that's not a way I'd attach
a bike to a roof rack.

And yes, we stopped selling roof racks in general maybe 5 years ago. As our
roof-rack vendor, a well-known & respected company, once told me- "There are
two types of roof rack users. Those who have driven their bikes into
something, and those who will." The decision had nothing to do with fork
damage, since there were already many alternative ways to attach bikes to
roof racks available.
>
> Matt O.


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