Just got this message from BMCR. I took the Cannondale in to get a rivnut installed today after I got the loose one out
We’ve looked at your Cannondale, and unfortunately the rivnut cannot be replaced as the hole in the frame is too large. It appears that either someone has drilled out the old one using the wrong sized drill bit*, or the old nut had been spinning in the frame for so long that it wore the frame away**. Feel free to collect your bike as soon as you like – sorry we don’t have better news for you.
Any other suggestions to fill the hole so I can attach a second bottle cage? Or is there a bigger rivnut that I can buy and install?
Success! Thank you so much MikeD. It worked perfectly and cost me under $8.
I measured the hole with some calipers and bought 5 M6 rivnuts off of eBay for $3.99 (free postage). I then bought some M6 socket head bolts from Bunnings ($3.15 for 3). The rivnut fitted in the hole snugly and using this DIY method with one of the hex bolts and a bigger M8 nut that fitted loose on the bolt I tightened the rivnut. The bottle cage holes fitted a M6 bolt as well, so I didn’t need to drill it.
Wondering how easy it would be to install rivnuts on a steel frame now.
so rivnuts - they don’t weaken the tensile strength of a frame tube? Reason I ask is that I am considering installing some on the underside of the downtube of my steel MTB frame (so I can put a cage on together with a full frame bag). But not being an engineer with good understanding of physics or metallurgy, I cannot work out how drilling holes into a tube’s surface would not create a significant stress point in the tube; and considering how hard MTBs get ridden, I would be afraid of the frame cracking at that point. As it stands I was planning on using some of banded bosses made by Elite.
… I’m sure Halbot/DrFrog have answered this question countless times before but I can’t be arsed doing a search (apologies).
Not an engineer, and only have enough of an idea about physics and metallurgy to be dangerous.
Downtube gets mostly stretchy forces rather than bendy forces.
As long as you use sharp drill bits and dont dint the tubing you are fine. Think of it a bit like tearing paper, if you fold it then tear it follows that line…
Personally too much work, bladder in framebag, Cages on forks if you need the extra space. If you still need space your taking too much.
doesn’t do much to strength
hole is round (duh) so no stress concentration and the stresses are highest/concentrated and the joints between the tubes (welds , lugs, hemp twine reinforced orgainic resin and what have you) this is why material is removed from these middle of the tubes to save weight a’la double butted tubes, stresses are lower there.
unless your tubes are crazy thin or you carry mercury in your bottle you’ll be fine (in these cases the hole won’t cause the problem hanging stuff off it might initiate cracks that could lead to failure) IS MTB = will be fine*
i even drilled a set of bullhorns for internal cables (on the underside cos compression, i’m not totally stupid) and didn’t die
*check your frame for cracks now and again anyway even if you don’t install rivnuts, I am not a structural engineer, or a dentist as such, i can’t fix your teeth if you do manage to snap your frame ;p
P.S. if you do dent your frame HALBOT can do a API RP579 fitness for service (yes it is abbreviated to FFS) assessment for you [/O&G enginerd joke]
Is this a touring setup?
You can get some bottle holder bags that fit on your handlebars. Mate who just rode the Tour Divide used them.
Revelate feed bags.
I just drilled my steel CX frame on the downtube for rivnuts. I was sick of having no cage(s) on it and because #yolo. I started with a small drill bit and moved up until the hole was the right size. The rivnuts and cage installed fine.
