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Problem frame - to drill or not to drill?

ne0skne0sk Posts: 39
edited August 2014 in Workshop
Well, it seems the Cannondale R500 I purchased has a problem.........

The rear mech hanger bolts are threaded as is the thread in the hanger.

A Cannondale replacement purchased but the bolt size is now bigger (metric) so the holes in the frame are too small. I'm assuming the frame holes are unthreaded, if they are supposed to be then I have an even bigger problem!

2002 bike so ZERO chance of getting an original hanger.

Is drilling out the holes in the frame to accommodate the bigger hanger bolts an option? I have the right sized drill bits but am worried this could snowball into a complete disaster.

Am I best advised to leave alone and seek recourse from the seller (who may say "go away").

Risks of buying second hand..........

Posts

  • arlowoodarlowood Posts: 2,501
    Have a look on here

    http://www.derailleurhanger.com/cannondale.htm

    Can't see anything as far back as 2002 but you may see something that replicates what you have at present. Or maybe you can contact them and ask the question - they seem to specialize in derailler hangers

    Unfortunately a US based site but if you know what you need you might be able to find a UK source
  • imposter2.0imposter2.0 Posts: 11,051
    ne0sk wrote:

    Is drilling out the holes in the frame to accommodate the bigger hanger bolts an option? I have the right sized drill bits but am worried this could snowball into a complete disaster.

    Should be ok to do this, depending on the size difference between the old and the new holes - and whether there is enough metal remaining around the area of the holes to provide strength/support for other areas of the frame, if needed.
  • Monty DogMonty Dog Posts: 20,614
    If you're going from say 4mm to 5mm then it'll make no difference - make sure the drill is sharp and file-off any burrs.
    Make mine an Italian, with Campagnolo on the side..
  • ne0skne0sk Posts: 39
    Thanks for the advice.

    There's a leaflet in with the new hanger that ha a table referring to thread size. I think the bke currently has a 6-32 English whereas the new thread is M3x.5 Metric. Confusingly the table says the thread size changed in 1992, the bike is a 2002 so well AFTER this change so I don't understand that.

    Difference is tiny, not even 1mm.

    I'll try contacting the US guys thanks arlowood. Mine is the Hanger #17 that fit the CAAD4 1991-2006. No mention of bolt size though. Maybe this one has the bolt size I need

    Hmmmmm

    Looks like there are options.

    Very happy now!
  • foggymikefoggymike Posts: 862
    The frame isn't threaded. If it was me I'd be happy enlarging the holes if it was a small difference. Alternatively you could always source some suitable smaller bolts/nuts and washers of needed.
  • ne0skne0sk Posts: 39
    Took the plunge and gently drilled out the holes this morning.

    Success. New hanger safely and securely fitted.

    Thanks again everyone
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