carbon and bike rack clamps?

[Black Sheep]

We've got a Cruz roof rack which clamps the side of the down tube with two clamps one above, one below

is there a risk of damaging a carbon frame on this rack?

 

[figbat]

There is a risk, yes. The rack makers often warn against clamping carbon tubes or provide an adaptor for their use. That said, I have clamped my carbon road bike and two MTBs in my Thule Proride 591with no issues. I don’t clamp them very tightly, allowing the wheel straps to make sure the bikes stay attached - the frame clamp is largely just to keep it upright.

 

[fossyant]

Old inner tube and clamp lightly.

 

[figbat]

Old inner tube and clamp lightly.

I use a piece of inner tube if there are cables running down the tube (as there are on a couple of my bikes) - tube goes between the cables and frame. I also make sure the frame is clean and the clamp faces are clean, to avoid rubbing.

 

[CanucksTraveller]

Yes, clamping too tightly can potentially risk damaging a carbon frame. The clamp needs to grip just snug, but not too hard.

Most roof rack clamps are highly adjustable to cater for all widths of frames. I'm afraid I've got a Thule so it might not be directly relevant but on those it's easy to do by rotating the locking handle to the right width before you close it off, exactly as you would with a QR skewer on your wheels. I'd imagine the Cruz has something similar. Like Figbat says, the clamp is really there to stop lateral movement of the upright frame, it's the wheel tethers that hold the bike to the roof.

 

[youngoldbloke]

^ this + foam pipe insulation around the clamped area of down tube