carbon bikes and roof racks

chris_phillips

Anybody out there who has any knowledge on the prospect of fixing my carbon bike on a roof rack that uses a clamp system. Will it stress or crush the carbon? Or would it be a safe bet to place the bike in the boot. Any suggestions would be much appreciated.

ADIHEAD

I've been worried about doing the same thing so avoided it, for that reason, and in case I forget it's on there while passing under low trees....

MaxwellBygraves

If you can put it in the boot, then surely do?
I'm not sure re the roof rack question, never used one myself. But surely if you have option to stick in boot then do so!

chris_phillips

Thanks for the speedy reply. Not sure if i made the right move buying a carbon bike. feel as though i will have to treat it with kid gloves. I have just picked up a wilier it looks the part and rides well, just a little unsure at how safe a carbon bike really is, having read disaster stories on the forums. Are you quiet confident with yours or do you have reservations.I know its to late now because I have purchased it.

night_porter

Carbon fibre is stronger than aluminium so if you could put an ali bike on your roof then there will be no problem putting a cf bike there too.

The main difference between the 2 materials is that if you stress ali enough it will bend and stress carbon enough it will snap rather than bend. But let's face it if you bent an ali frame it is just as buggered as any snapped carbon and it is something we just do not do (intentionally that is).

If carbon fibre wasn't safe then they would not make high end or grand prix cars out of it.

Omar Little

I've had mine on the roof bars many times without a problem (although I prefer using a tow-bar mounted rack these days which i initially got mountain bike use but it is so convienient i use it with my road bike too now)

Just be careful and dont over tighten the clamps and you will be ok. Same advice goes for aluminium - although carbon will likely stand up to higher clamping stress than an aluminium frame will.

MaxwellBygraves

Chris Phillips wrote:

Thanks for the speedy reply. Not sure if i made the right move buying a carbon bike. feel as though i will have to treat it with kid gloves. I have just picked up a wilier it looks the part and rides well, just a little unsure at how safe a carbon bike really is, having read disaster stories on the forums. Are you quiet confident with yours or do you have reservations.I know its to late now because I have purchased it.

Wouldn't worry about the horror stories mate.
Carbon bikes are fairly tough, just treat it with respect and it will be fine.

chris_phillips

Really appreciate your comments gents.So many conflicting reviews on this topic, Think i will take the cautious approach and stick it in the boot. fair point with regard to formula 1 though, prob slightly higher grade carbon, but carbon all the same.
regards chris

cougie

Mines done 100s of miles on a roof rack no problem. You COULD crush the tubes if you clamp them too tight - but if you're sensible - then its no bother.

But if you have space in the car - I'd put it in there every time.

bigpikle

the only advisory I have seen on this was the type of rack where you remove the front wheel and attach to a QR on the rack - they advised NOT using it for forks with carbon dropouts (dropouts not forks). All my carbon forked bikes have metal dropouts so I've never worried and never had an issue....

moonshine

Bigpikle wrote:

the only advisory I have seen on this was the type of rack where you remove the front wheel and attach to a QR on the rack - they advised NOT using it for forks with carbon dropouts (dropouts not forks). All my carbon forked bikes have metal dropouts so I've never worried and never had an issue....

ditto...

my thule fork clamp rack advises against using with carbon droppout forks, but my Felt F3 and PX stealth have alloy fork ends on carbon forks and ive never had a problem.

I also have a proride thule rack and i think the only advice ii can give is to go canny when clamping the downtube - don't go overboard tightening the clamp.

never had any problems

antfly

MaxwellBygraves wrote:

If you can put it in the boot, then surely do?
I'm not sure re the roof rack question, never used one myself. But surely if you have option to stick in boot then do so!

I couldn't agree more, boot is always best. I put my bike in my mini.

arlowood

Hi Chris

Started a thread on this topic some time back - you might be interested in some of the posted comments

http://www.bikeradar.com/forum/viewtopi ... sc&start=0

Seems that Thule in particular do NOT recommend their front fork clamp design (model 561) if your drop-outs are carbon. Could be to do with lateral stresses in side winds possibly. However others have posted that they experienced no issues with their carbon drop-out bikes when using this type of carrier. Their full frame carrier is a possible option to consider (591 model I think) but again the profile is much less aerodynamic and there may be issues with getting the downtube clamp fixed on some of the more esoteric carbon frame designs.

As has already been stated - if you have the room to stick your bike inside the car then that is a much preferred option.

crankycrank

I have to ask the question. If your sub 17lb bikes CF fork dropouts cannot stand being clamped to a roof rack how can you expect them to withstand the stresses of a 200lb+ rider on board who would certainly use at least the same amount of clamping force on the front wheel and would certainly put more stress from all directions on them? Not trying to be a smartass but I just don't see the logic even taking into account the high wind speed on top of a car. I suspect Thule is just protecting themselves against users who damage their forks by using gorilla strength to clamp the dropouts.

Omar Little

Here is a video of a carbon frame being clamped a vice http://www.youtube.com/watch?v=SDVpRSNtcPQ&

antfly

It should be ok if you have your bike facing forward but if it is facing backwards on the roof things can go horribly wrong.

Eskimo427

I've done about 2k miles with my Scott Spark on the roof using a clamp carrier and the bike is fine. I've even hit the bike with a rubber mallet (accident!!) and it's been fine too. Carbon is a lot stronger than people think it is.

ajb72

crankycrank wrote:

I have to ask the question. If your sub 17lb bikes CF fork dropouts cannot stand being clamped to a roof rack how can you expect them to withstand the stresses of a 200lb+ rider on board who would certainly use at least the same amount of clamping force on the front wheel and would certainly put more stress from all directions on them? Not trying to be a smartass but I just don't see the logic even taking into account the high wind speed on top of a car. I suspect Thule is just protecting themselves against users who damage their forks by using gorilla strength to clamp the dropouts.

Don't worry, you're not being a smartass - you're just talking complete nonsense! The clamping force of a mechanical clamp is significantly higher than the pressure of a rider weight or hand tightened skewer. More importantly though, the stress or rider weight is spread throughout the whole bike and not all placed on the forks. Further more the pressure applied by a rider is placed down through the forks, so the contact point is in the dropout but the stress is spread upwards and absorbed through the fork and frame.

The mechanical clamp force places pressure on the stays in a sideways motion - in an area only designed to withstand a small wheel skewer. Think of it another way - if I were somehow to be able to balance my weight on top of my handlebars I think there is a pretty fair chance there would be no negative impact on the frame or forks. If However I placed the bike sideways and stood on the forks I can imagine them suffering a horrible fate.

For my part, I own a Thule 591 and a carbon frameset. GIven the option the bike stays in the car, but otherwise I am just careful in how I clamp it and place the clamp as near to the BB as possible, where the tubing is at its thickest.

proto

ajb72 wrote:

Don't worry, you're not being a smartass - you're just talking complete nonsense!

The clamping force of a mechanical clamp is significantly higher than the pressure of a rider weight or hand tightened skewer.

Err ........ I think it's you talking nonsense. On a Thule fork mount type bike carrier the 'mechanical clamp', as you describe it, is a hand tightened skewer, so I really don't understand what you are on about.

I'm with CrankyCrank, I've carried my LOOK 585 and BMC Pro Machine, carbon drop outs and all, on this type of carrier with no problems and will happily do so again.

Monty Dog

I agree with Proto and Cranky too - this question appears on forums every 6 months or so and the answer is always the same - more stresses are exerted on a bike whilst riding that when on a roofrack. I'd defy anyone to crush a solid carbon dropout using a QR - and if they did they're just a stupid!

luv2ride

When I picked up my Roubaix from the LBS they specifically warned me about using a roof carrier with a clamp. They had a customer crush their frame by overtightening the clamp, apparently. Mind you, they also really dissed Boardman carbon frames too, so not quite sure of the "quality" of their advice?

Mind you, I've been terrified of causing damage to the frame ever since!

Brian B

Sorry to post this but plenty of frames have been damaged by clamping.

See this website with one example:-

http://www.carboncyclerepairs.co.uk/index.php?repairs

colsoop

You can damage a frame by clamping it down too hard but the thule roof clamp, which is what i sue is a hand tight job and i really doubt you could get enough force in it to damage the frame.

I regularly clamp my look 486 to the roof rack without issue and also my planet x, both carbon frames.
The clamp is only there to add extra stability and to stop the frame sliding about.

As long as the bike is upright and the clamp can't slip about on the frame you wont have issues.

wicked

Its not really a clamp that goes around the downtube merely a means of holding the bike in an upright position. Only time there are problems is when idiots tighten the "clamp" right up thinking it's necessary.

If you really want to be safe I would wrap a rag around the tube first and then loosely tighten the clamp just enough to stop the bike from wobbling around.

hopper1

There was an issue highlighted recently, in the TTF forum.
One of the guys was transporting his P3, using a Thule 561(fork clamp) and the clamp backed off, allowing the forks to bounce out and the bike to swing ot and hang along the side of his car :shock:
I had just bought a 561 when I read that, and as I have a P3, the rack is still in the sealed box!
But, I probably will try it soon. :?

antfly

I think the issue with the ones that attach to the dropouts is the force generated by the winds on the clamped fork, you don't get the same forces when cycling. I know the venerable Richard Hallett had one side come loose and the other side then break but he did have the bike facing backwards.

proto

hopper1 wrote:

There was an issue highlighted recently, in the TTF forum.
One of the guys was transporting his P3, using a Thule 561(fork clamp) and the clamp backed off, allowing the forks to bounce out and the bike to swing ot and hang along the side of his car

The fork clamp on my 561 is lockable (the lock is an optional extra, I think). If this is secured, I can't see how it can come undone. :?

Monty Dog

I think the answer to all those who are 'afraid' to use their precious carbon bikes on a roofrack / turbo trainer / in the rain is to get a steel frame made out of gas-pipe!

hopper1

proto wrote:

hopper1 wrote:

There was an issue highlighted recently, in the TTF forum.
One of the guys was transporting his P3, using a Thule 561(fork clamp) and the clamp backed off, allowing the forks to bounce out and the bike to swing ot and hang along the side of his car

The fork clamp on my 561 is lockable (the lock is an optional extra, I think). If this is secured, I can't see how it can come undone. :?

Evidentally, it backed off from the inside!

I haven't looked, but I have been informed that Thule have now removed the comments about CF dropouts.