# Are Drain Holes Necessary?



## TheHamster (Apr 15, 2007)

Hello,

I recently acquired a new steel frame and was surprised to find that there are absolutely NO drain holes of any kind anywhere in the frame. Once the cranks and headset are installed, I can see no way for water (or air) to enter the frame anywhere. But I am worried about condensation. Would I be better off drilling some small holes in the ends of the chainstays and/or BB area to let air circulate? Any opinions and/or advice are/is appreciated.


----------



## Walt (Jan 23, 2004)

*Imo*

...they are not needed. Leave the frame as it is. Assuming the tubes really are sealed, there is very little moisture in the gasses present inside them. And there's very little oxgen, too, meaning that you should not be able to get much/any rust.

-Walt


----------



## smdubovsky (Apr 27, 2007)

I didn't add them. Whatever is left inside will cause a little surface/flash rust and consume the O2. Once that runs out the rust will stop.


----------



## pyranha (Aug 7, 2007)

While retrofitting them may be a hassle, 
I just did a frame repair for an Independent Fabrications where the seat tube had rusted through at the bottom bracket due to no drain hole being present. I know some people build this way, but I really do not understand it. All other tubes can be sealed without issue, but seat tubes present a problem. I am quite sure this is arguable.


----------



## pvd (Jan 4, 2006)

A drain hole in the BB and seat tube are absoluely required. Water always gets in. You have to let it out.


----------



## Schmitty (Sep 7, 2008)

I'm with PVD on this one, though not sure I would 'retrofit' them.

I also have a sneaking suspicion that a 'sealed' bike tube isn't as sealed as we may think. I've seen/had way too many FATs with downtubes that were full of rust... 'sealed' downtubes.. blind water boses, etc.. and not from the bb/st/dt area rusting and letting water in either. I've also cut apart a few of my sealed tube frames and found plenty of rust in them, even in a fairly dry climate.

-Schmitty-


----------



## jay_ntwr (Feb 15, 2008)

Schmitty said:


> I'm with PVD on this one, though not sure I would 'retrofit' them.
> 
> I also have a sneaking suspicion that a 'sealed' bike tube isn't as sealed as we may think. I've seen/had way too many FATs with downtubes that were full of rust... 'sealed' downtubes.. blind water boses, etc.. and not from the bb/st/dt area rusting and letting water in either. I've also cut apart a few of my sealed tube frames and found plenty of rust in them, even in a fairly dry climate.
> 
> -Schmitty-


We need a real chemistry major to explain this, but I seem to remember from chemistry that the way the oxy-reduction reaction works is that the ions form in the absence of oxygen. In other words, seal the whole thing, paint it, then get a single nick in the outside layer of the paint and that's what allows the reaction to begin. what happens next is that the rust will form inside the tube because of the oxygen presence on the outside of the tube. It then slowly rusts away from the inside out unless the outside is completely protected such to eliminate the oxygen. And consider that welded together, that oxygen presence can come from anywhere.

Now again, I'm not chemistry so it would be great to have someone that knows about this chime in and explain it.

And yes, a drain the the BB shell seems like a silly thing not to have in a steel bike to me. It doesn't have to be a big one, just something.


----------



## Walt (Jan 23, 2004)

*Um, no.*

Without going into lots of detail, for all practical purposes steel is impermeable to all gasses (that's what makes the argon, oxygen, acetylene, CO2, etc stay inside your tanks, even at thousands of PSI). So rust on the outside will only mean rust on the inside if the steel rusts all the way through - from the outside first.

It's just oxidation - rust is iron oxide. Various things can speed up that process, various things can inhibit it, but there is no magic. No oxygen=no oxidation.

BTW, I agree that the seat tube (since it cannot be sealed) should always have a drain hole.

-Walt



jay_ntwr said:


> We need a real chemistry major to explain this, but I seem to remember from chemistry that the way the oxy-reduction reaction works is that the ions form in the absence of oxygen. In other words, seal the whole thing, paint it, then get a single nick in the outside layer of the paint and that's what allows the reaction to begin. what happens next is that the rust will form inside the tube because of the oxygen presence on the outside of the tube. It then slowly rusts away from the inside out unless the outside is completely protected such to eliminate the oxygen. And consider that welded together, that oxygen presence can come from anywhere.
> 
> Now again, I'm not chemistry so it would be great to have someone that knows about this chime in and explain it.
> 
> And yes, a drain the the BB shell seems like a silly thing not to have in a steel bike to me. It doesn't have to be a big one, just something.


----------



## D.F.L. (Jan 3, 2004)

You might want to treat the seat tube with a rust inhibitor and keep a pool of oil (or something even better) at the bottom. Empty frequently.


----------



## Blaster1200 (Feb 20, 2004)

D.F.L. said:


> You might want to treat the seat tube with a rust inhibitor and keep a pool of oil (or something even better) at the bottom. Empty frequently.


I was thinking it may be better to use DOT 3/4 brake fluid in the tubes since it absorbs moisture. Change the brake fluid every couple years to remove the moisture and begin with fresh brake fluid and the corrosion inhibitors additibes built in it. Just don't get it on the paint.

...ah nevermind...


----------



## TheWoodsman (Aug 27, 2010)

I just Waxoyl inject all the tubes and prefer drain holes, as I top up the inhibitor on a regular basis. 

My take on this is; if you are not the type to regularly re-inject the Waxoyl or Framesaver type stuff then sealed tubes would be better. If you apply the inhibitor from new and keep it regularly topped up, say annually then go for drain holes. I think the latter will last longer than the former.


----------



## Schmitty (Sep 7, 2008)

Walt said:


> Without going into lots of detail, for all practical purposes steel is impermeable to all gasses (that's what makes the argon, oxygen, acetylene, CO2, etc stay inside your tanks, even at thousands of PSI). So rust on the outside will only mean rust on the inside if the steel rusts all the way through - from the outside first.
> 
> It's just oxidation - rust is iron oxide. Various things can speed up that process, various things can inhibit it, but there is no magic. No oxygen=no oxidation.
> 
> ...


But less than a pin hole anywhere is a different story I'm guessing. Porosity in the weld? Gas tanks go through rigorous testing and I'm guessing manufacturing for their intended purpose. Maybe ultra thin wall steel is porous to a degree.

I'm curious about temp gradients as well.. the whole cold glass on a warm day deal.

Who knows. Some of the worst frames I've seen were 'sealed'.

-Schmitty-


----------



## Walt (Jan 23, 2004)

*It's impermeable.*

For all practical purposes, steel (even very thin walled steel like bike tubing) is impermeable to all gasses and liquids. Yes, if there's a *hole*, then all bets are off.

Condensation occurs when you've got water vapor in the air and a temperature gradient (ie, cold glass of beer, warm air). Not relevant here, since I have a hard time imagining much water being present in the relatively hot gas left inside the tube when the final weld is finished. And once again, even if there is a little bit, you still have a finite supply of O2 available.

I think that the bottom line is that if you even kind of try to take care of your frame, it doesn't matter, and if you neglect it enough, it will rust no matter what you do. So do whatever makes you happy and call it good.

-Walt



Schmitty said:


> But less than a pin hole anywhere is a different story I'm guessing. Porosity in the weld? Gas tanks go through rigorous testing and I'm guessing manufacturing for their intended purpose. Maybe ultra thin wall steel is porous to a degree.
> 
> I'm curious about temp gradients as well.. the whole cold glass on a warm day deal.
> 
> ...


----------



## Francis Buxton (Apr 2, 2004)

Even with a drain hole in the BB at the bottom of the seat and down tubes, you're going to be able to have moisture present. I doubt that anyone gets the drain hole exactly at the edge of where the seat or down tube meets the BB shell, meaning there is some kind of place for the water to "pool", no matter how shallow.

I've read so many debates on this topic, and it's never "over". I say just put framesaver in the frame, ride it and don't fret too much. It seems to very much be down to personal opinion, and how often you ride through 3' deep stream crossings.


----------



## Schmitty (Sep 7, 2008)

Agreed Francis. You can get the hole very close to the inner edge of the st, of course you would need two, one on each side of the bb shell arch. There's numerous other things to do to reduce water intake as well.

My point is, it's not 100% cut and dry (ahem) either way. Vents don't lead to rusting across the board, and 'sealed' tubes don't prevent rust across the board. Visually sealed isn't sealed. Various metals have various gas and vapor diffusion coefficients.. that's just the straight up materials, so also consider a pin hole.. smaller than a pin hole even.. anywhere a bottle boss is silver brazed on for example, slopy tig weld, etc.





-Schmitty-


----------



## mtnbikecrazy55 (Jul 26, 2007)

Just get a ti frame and be done with it :-D


----------

