Talk Composites - The Forum for Advanced Composites

Advice needed for reinforcement of cablestopper

http://www.talkcomposites.com/Topic14394.aspx

By Divo - 1/3/2015 7:37:13 PM

I have a new carbon roadbike frame with in the head tube a cable stop built in.

From the outside of the headtube the outercable ends in it, and then it guides the innercable through the frame.

This cablestop (alu hollow tube) can be seen at the inside of the headtube. It's partly uncovered and I think it’s a bad construction. Vulnerable for breakingout (see image)

 

I want to cover it on the inside with tiny pieces of carbon so the cable stop will be totally locked up on all sides.

 

Think I only need a few pieces of carbon of 2 x 4 cm and some resin and hardener.

What do you advise me?

Hope you can help me out
By Dravis - 1/5/2015 11:52:46 AM

Yes I think you do ... If a bare metal aluminium part is directly in contact with Carbon fibres, there will be galvanic corrosion (caused by the electric potential difference between aluminium and carbon)

It will cause the aluminium part to "swell" up with aluminium oxides and crack the bonding to the CF.

I have seen this i a number of CF bike frames, but mostly some years ago when the CF frames were still very "new" ..

If there is no aluminium part there, that just means that you will not have that particular problem... If you want to reinforce an existing cable stop made from CF, thats probably best done by adding more fibre or a high strength fibre filled epoxy.

I would do this:

Drill the Alu stopper tube out, and replace it with a CF woven tube of suitable size, glue that in place with a small amount of CF fibres as reinforcement.

At the same time, key the area around the stopper, maybe even the whole inside of the head tube, and epoxy an extra layer of CF weave in there..

(Since you say it is "uberthin"  ... Cool)