Drilled an alumimun frame. Still safe?
11-11-15, 05:01 PM
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Drilled an alumimun frame. Still safe?
Some years ago, I drilled two holes into a step-thru aluminum bike with a single downtube and tapped them for a water bottle holder. I've been meaning to give the bike to someone, but after learning more about aluminun frames, I am concerned that these holes might have weakened the frame. Am I being overly cautious?
11-11-15, 09:24 PM
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Millions of bikes have many holes in them, bottle bosses/vent holes. Just watch for cracks developing. I wouldn't worry too much. Andy
11-11-15, 10:29 PM
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If you've got threaded rivnuts in the holes, then you should be okay. As Andrew mentioned, you should be okay, and just look for cracks. If you have the threaded inserts, they will act as a reinforcing ring around the holes.
11-12-15, 11:18 PM
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Thanks. Appreciate the comments and advice. Never heard of rivnuts, but it appears they're used all the time for this purpose.
The frame was thick enough to tap, but more threads would be nice. The tool seems affordable. Maybe I'll get one.
The frame was thick enough to tap, but more threads would be nice. The tool seems affordable. Maybe I'll get one.
11-13-15, 10:45 AM
#5
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there are workarounds to expand the rivet like function of a riv nut without the shop tool
one is using an old QR skewer the eccentric of the lever multiplying the effort ..
well greased 5mm bolt and a few washers under it also is functional.
Perhaps, bump the bolt up to 8.8 tempered steel bolt for that purpose?
essentially you are pushing the flange face on the outside down, while pulling the threaded part upwards,
and that compression forces the riv nut outside, wider pressing into the drilled hole.
one is using an old QR skewer the eccentric of the lever multiplying the effort ..
well greased 5mm bolt and a few washers under it also is functional.
Perhaps, bump the bolt up to 8.8 tempered steel bolt for that purpose?
essentially you are pushing the flange face on the outside down, while pulling the threaded part upwards,
and that compression forces the riv nut outside, wider pressing into the drilled hole.
Last edited by fietsbob; 11-13-15 at 10:48 AM.
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