# Water bottle boss hole size.



## seeborough (Feb 3, 2004)

This being the fixed-gear conversion forum and on the off-chance that someone on this forum has done this before - what bit size would I use to drill holes for water bottle bosses? The guys at the shop have the rivnut parts and tools, but, since they usually just replace them into existing holes, they are not sure about hole size.


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## UrbanPrimitive (Jun 14, 2009)

This strikes me as an odd question. Here's what little I know on the subject:

As I recall the average bolt used to secure water bottle cages is 4mm (I think. Double check, as my bike doesn't have any). I'm not familiar with "rivnut" parts, but I'm guessing this is an after market, non-brazed bottle boss of some kind? Honestly my brain goes straight to zip-ties for securing the bottle cage. It may not be pretty but it could get the job done. Water bottle bosses are generally brazed on, in which case the drill size is dictated by the O.D. (outer diameter) of the boss rather than the I.D. (inner diameter). If the guys at your local shop are saying they can install this gear if you drill the holes check with them. If they claim to have the hardware and knowledge to install it but can't tell you what size to drill the holes, run away and don't look back.


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## seeborough (Feb 3, 2004)

Let me try to remove the oddness of my question. 
In years past, LBSs were able to replace stripped or loose water bottle bosses in aluminum frames, early Cannondales apparently being prime candidates for failure. Those bosses were punched into the frame with a rivnut (size M5, if I remember right) tool. Our shop still has the tool and can reorder the rivnuts. However, since they have only replaced worn ones and never actually drill new holes, they have had no need to know their size. 

For me, things like water hose clamps, zip ties or all kinds of tube-clamping water bottle holders are too jury-rigged. Seat post or bar mounted holders are out as well. What remains is the option of drilling four holes into the frame. Since it is an old Schwinn with relatively thick tubing, I would not anticipate any problems with the integrity of the frame. My question to the forum is if anyone has done this and remembers the size of the hole before the rivnut goes in.


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## UrbanPrimitive (Jun 14, 2009)

Understood. Thanks for the clarification. Now knowing better what we're talking about the very best I could manage is guess, which would be no more accurate than your guess. All I can say is good luck!


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## Dave Hickey (Jan 27, 2002)

seeborough said:


> Let me try to remove the oddness of my question.
> In years past, LBSs were able to replace stripped or loose water bottle bosses in aluminum frames, early Cannondales apparently being prime candidates for failure. Those bosses were punched into the frame with a rivnut (size M5, if I remember right) tool. Our shop still has the tool and can reorder the rivnuts. However, since they have only replaced worn ones and never actually drill new holes, they have had no need to know their size.
> 
> For me, things like water hose clamps, zip ties or all kinds of tube-clamping water bottle holders are too jury-rigged. Seat post or bar mounted holders are out as well. What remains is the option of drilling four holes into the frame. Since it is and old Schwinn with relatively thick tubing, I would not anticipate any problems with the integrity of the frame. My question to the forum is if anyone has done this and remembers the size of the hole before the rivnut goes in.


Are you using a Rivnut that takes a 4mm bolt?

Here is some more info. I'm still searching for the installation guide

http://www.cardinalcomponents.com/fasteners.htm


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## Dave Hickey (Jan 27, 2002)

Dave Hickey said:


> Are you using a Rivnut that takes a 4mm bolt?
> 
> Here is some more info. I'm still searching for the installation guide
> 
> http://www.cardinalcomponents.com/fasteners.htm



It's in here but it depends on what size Rivnut you are using

http://www.cardinalcomponents.com/fasteners/RivnutDesignGuide.pdf


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## Pablo (Jul 7, 2004)

Let us know how it works. It'd be nice to bring a water bottle on fixed rides on my Pista.


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## seeborough (Feb 3, 2004)

Why am I starting to feel like the guy who gets to jump out of the airplane first? My Pista-riding buddy said the same thing. 

I'll report back when I get it done...


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## Pablo (Jul 7, 2004)

seeborough said:


> Why am I starting to feel like the guy who gets to jump out of the airplane first? My Pista-riding buddy said the same thing.
> 
> I'll report back when I get it done...


Space monkey! It's for the greater good.


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## seeborough (Feb 3, 2004)

*Update.*

With a rivnut outside diameter of 7.48 mm, a 7.5 mm drill bit will give the closest hole size for an M5 nut. I used a 5/16 bit, which gave me a hole size of 7.8mm. Here are some pictures:


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## Dave Hickey (Jan 27, 2002)

seeborough said:


> With an outside diameter of 7.48 mm, an 7.5 mm drill bit will give the closest hole size for an M5 rivnut. I used a 5/16 bit, which gave me a hole size of 7.8mm. Here are some pictures:



Nice....That turned out great


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## Pablo (Jul 7, 2004)

Looks great! How did you center the holes on the tube?


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## f3rg (May 11, 2008)

A 19/64 bit would get you a tiny bit closer to optimal, but this turned out great. Thanks for sharing the info!


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## seeborough (Feb 3, 2004)

Pablo said:


> Looks great! How did you center the holes on the tube?


Digital calipers to center and yarn, held in place with masking tape, strung down the middle of the seat tube. I used a pilot punch, sharp drill bit, low rpms and a few drops of chainsaw lube. Despite my handheld old Bosch drill, the holes came out pretty round.

Disclaimer: The tube walls on an old Schwinn are quite hefty. I am not sure that I would do this to a higher quality steel frame.


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