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Drilling into an aluminium frame tube

WheelspinnerWheelspinner Posts: 5,867
edited September 2011 in Workshop
I have a Cannondale CAAD8 frame currently set up as a single speed. I removed the derailleur cable stops from the head tube when I did the conversion as they were useless and (IMO) spoilt the look of the bike, since they resembled Shrek's ears.

The frame is now just polished alloy finish, very clean and shiny.

I have some other cable stop fittings which I could use if I want to go back to a geared drivetrain. These are normally riveted on the downtube, but my question is does anyone know whether drilling (tiny!) holes in the 'Dale tubing is going to wreck it? Haven't measured the diameter, but I'd guess no more than a 2mm hole for each rivet required.
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Posts

  • Monty DogMonty Dog Posts: 20,614
    Depends whereabouts you drill the holes and that the holes are clean (new, sharp drill) and free of burrs. The downtube / headtube junction is one of the most highly-stressed parts of the frame so make sure that the job is done well and that you use the right type of rivets with the correct size of holes.
    Make mine an Italian, with Campagnolo on the side..
  • I have an ancient aluminium framed winter bike (now just retired unhurt after 33000 miles) and years ago I tapped the down tube M5 to suit a cable stop (in the same place as down-tube levers used to be fitted) as the ones fitted to the head-tube were badly placed and the cables fouled the brakes.
    I have had no problem at all, with no sign of crackk propagation from the hole.

    I've broken several steel frames here though, as the brazing of the bosses on to the frames sets up stresses and creates stress-raisers.
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