Carbon bars

[lancer17]

Two questions
Ortlieb states that you can not use there handle bar bag with carbon bars and stem, has anyone used these and is it safe to do so ( Thinking of the Thorn carbon comfort bars)?

Is there any advantage apart from weight saving with carbon bars, seat post?

[julk]

I e-mailed a similar question to Andy Blance - here is his reply :-

'I can see no problem with using a bar bag mount on our carbon riser bars.
These are carbon, wrapped onto an ultra-lightweight alloy skeleton, which in
itself would be too lightweight for use as a handlebar. The combination of
the carbon and the alloy produces a very strong, light and comfortable bar.
The alloy makes the carbon much more resistant to crushing damage.
Having said that, I use one of our accessory bars to mount my bar bag...this
gives me a better line of sight to the ground immediately in front of the
wheel, it lowers the C of G of the bag and still allows me to mount a light
and computer on the bars.'

In my opinion an additional advantage of carbon components over aluminium alloy is the greater shock absorption.

[geocycle]

Mounting a bar bag on the accessory bar sounds like a really good idea for the reasons quoted by julk.  Has anyone tried this with an ortlieb ultimate 4 on a flat (comfort)barred RT?  I was wondering what the clearances would be like for getting access to the bag and reading the map that mounts on top.  At the moment mine mounts on the bars and access to the press-studs is difficult.  I know longer ortlieb brackets are available but these really push the bag a long way forward.

[Ashley]

I'm curious, why would the bracket of an Ortlieb Handlebar bag exert any greater force than the clamp of the handlebar stem? 

[Audax hopeful]

I don't think the bracket is a problem, but the tensioning wire could be - it might cut through a carbon bar or stem, but is of course not a problem with alloy bars and stem. Carbon wrapped alloy is probably ok, but the wire might still cut into the outer carbon enough to look unsightly - and might compromise strenghth over time. Personally I wouldn't use carbon bars/stem for endurance/touring/commuting applications, even though some of the bar shapes seem really clever. As yet I'd say they're really only for race (and possibly training) bikes, in much the same way as carbon frames!!

[neil_p]

Re the question about why the bar bag bracket might damage the carbon bar more than the stem clamp.  I seem to remember reading that carbon bars are reinforced where they clamp into the stem, but not anywhere else.  I presume manufacturers are very cautious when saying what can and can't be clamped on to a carbon bar - any failure of the carbon is 99% certain to end in a wipe out, which is bad for the cyclist and no doubt bad for business too! 

[jonathan]

I have never used any kind of carbon bar so cant comment in any way, nor do I use a Thorn accessory bar. I do however have a second stem mounted upside down below my handlebars. Clamped in this is a 6" piece of 25mm electrical conduit, as this was the only thing of the right size I had kicking around when I se it up. My bar bag mount has been clamped to this for 6 months or so now with no sign of any damage.

I wonder whether electrical PVC is stronger than carbon fibre.