Drainage holes?

[WheelNut]

Hey Everybody,

I'm currently working on my second frame right now and I've realized that I have not yet considered drainage in the design. Its a steel frame, horizontal top tube, lugged, and with standard sized tubes. This will be a "gravel bike." I'm hoping to get some advice on how to address drainage in the frame.

So, providing drainage at the BB is in my plan already. Probably a 7/32" hole at the bottom of the BB. Now I'm assuming that the seat tube, down tube and chain stays will all drain into the BB. What about the top tube and seat stays? I thought of drilling a hole (1/2") in the head tube at the center of the TT-HT joint, and a hole in the seat tube at the center of the TT-ST joint (see attached image). This would allow moisture in the top tube to move into the head tube or seat tube. Also, as I understand it this area is not a stress point and a hole can be drilled without trouble (wrong?). For the seat stays I'm thinking of a small hole near the bottom. These holes should allow me to spray anti-corrosion agents into the tubes yearly. Is this a sound plan, or is this something I shouldn't worry about?

Thanks in advance.

[David Tollefson]

I tend toward large downtubes, and my frames are fillet-brazed, so...

I use 3/8" for seat- and top tubes, but for the downtube drain holes I'll take up to 3/4" depending on the tube diameter (at the headtube) and available space in front of the seat tube on the BB shell. For seatstays I'll do 1/4", and for 1/2" seatstays or the 3/4" wishbone stub into the seat tube I'll use the same. Don't forget drain holes at the bottom of the seatstays, and the dropout end of the chainstays. I run linseed oil throughout the frame, but advise to pull the seatpost and fork fairly often to let the whole thing air out. YMMV.

[e-RICHIE]

Any hole from 1/8" to 1/4" is fine, will do the job, and more than enough.

[Andrew R Stewart]

When I started out I used tiny (1/8" or less) vents every where. Then went in two different directions at the same time. Main frame got big ones, up to 1/2" and stays got hidden ones (through bridges or in the seat tube). Then a painter took issue with my 'cleverness" hidden vents still leak wash and grit...

Now I vent the main frame with aprox 3/16" to 1/4" holes at both ends to insure full washing out and drying. Stays and blades get smaller, usually 3/32" at both ends, are soaked out then sealed with brazed in nails. The shell gets an aprox 3/16" drain hole as close to the bottom as possible.

I completely agree that periodic (as dictated by exposure) pulling of the post and draining the frame is a very good thing. Andy (who has watched as many fluid ozs. dripped out on frames many times during servicing customer bikes.)

[WheelNut]

Now I vent the main frame with aprox 3/16" to 1/4" holes at both ends to insure full washing out and drying. Stays and blades get smaller, usually 3/32" at both ends, are soaked out then sealed with brazed in nails. The shell gets an aprox 3/16" drain hole as close to the bottom as possible. )

When you say "soaked out" does that mean you soak the interior of the tube with a rust inhibitor, drain it all out, and then seal it up by brazing?

Thanks for the feedback guys!

[Curt Goodrich]

I don't mean to speak for Andy. I'm fairly certain he means to soak and dissolve the flux that's inside the tubes. That's the same technique that I use along with the thousands of frame builders that came before us.

[Andrew R Stewart]

IMG_0411.jpgYes, Curt says what I meant. Hot water flushing (soak and drain), the hotter the better. After confirming all is dry inside the tube those tubes to be sealed by plugging the vent holes with nails and brazing are done. Here's an early and makeshift soak tank which in this step has Evpo Rust solution (after a water soak/flush for the flux). These days I use a PVC sewer pipe with an immersion heater.

[steve garro]

You will never regret 1/4" - 5/8" holes at major tube junctions once you have shaken a frame for hours trying to remove a jangler


- Garro.

[Michael Gordon]

...jangler

I always wondered what the technical term was for those!

[steve garro]

I always wondered what the technical term was for those!

Jangler is even spell-check approved!

- Garro.

[Andrew R Stewart]

You will never regret 1/4" - 5/8" holes at major tube junctions once you have shaken a frame for hours trying to remove a jangler


- Garro.

Anyone who has worked in a 1970s Raleigh shop will understand this... Andy.

[Michael Gordon]

OK, so on the topic of janglers, or maybe there is a different technical term for these little guys, here is something I am dealing with along similar lines...

In the seat stay(s) [can't tell if it is one or both of them], I can here what sound like little grains of sand "jangling" about as I rock the frame. The stays were well flushed with 1/8 inch holes at the top and bottom. After soaking, I hit the stays with a heat gun until they stopped steaming. All seemed plenty dry and jangle free, then I sealed up the holes. Later on, I started to hear the little grains. I'm guessing this is just flux that event that eventually loosened up. I have heard this on steel frames from other builders as well.

Any wisdom for avoiding this?

[steve garro]

OK, so on the topic of janglers, or maybe there is a different technical term for these little guys, here is something I am dealing with along similar lines...

In the seat stay(s) [can't tell if it is one or both of them], I can here what sound like little grains of sand "jangling" about as I rock the frame. The stays were well flushed with 1/8 inch holes at the top and bottom. After soaking, I hit the stays with a heat gun until they stopped steaming. All seemed plenty dry and jangle free, then I sealed up the holes. Later on, I started to hear the little grains. I'm guessing this is just flux that event that eventually loosened up. I have heard this on steel frames from other builders as well.

Any wisdom for avoiding this?

You will never regret 1/4" - 5/8" holes at major tube junctions once you have shaken a frame for hours trying to remove a jangler


- Garro.

- Garro.

[Rich Beaudoin]

Just use larger holes and don't seal the holes. Let the tubes breathe

[steve garro]

IMG_0754.JPG

Just use larger holes and don't seal the holes. Let the tubes breathe

- Garro.

[WheelNut]

Excellent, thanks guys. The photos are particularly helpful. I'm not much of a verbal learner, haha. I'll have to build up a little immersion tank in the basement.

If sealing up a tube with nails is the chosen method of finishing after drying with a heat gun is there any other treatments done to the interior of that tube? Do you use a corrosion inhibitor first, or is the level of atmospheric moisture contained within that tube not enough to cause any issues? I suppose a corrosion inhibitor might be damaged or cause problem when brazing the nails in place to seal the tube, is that possible?

[Andrew R Stewart]

The only rust throughs I've seen have been in tubes with access/vent holes BUT what got in couldn't (or wasn't allowed to) get out. The two locations I've seen most commonly (not that rust through is a common issue) are the top tube and the chain stays. Water will enter the top tube via the seat tube vent but as the post almost but not quite blocks off the exit this water will sit at the tube's low point and fester away. What is a common event is to rotate a bike on the repair stand so that head tube is lowest and watch the slimy water drain through the headset. Chain stays see water from the BB, the drop out end vents and any cable ports. If the BB shell is a socketed one this water will usually flow back into the shell and depending on their being a suitable drain hole there maybe get out maybe not. If the shell is a welded or filleted jointing and if the stay vent hole isn't at the very bottom of the stay's circumference then the water will pool at the low point, usually at the shell end.

So I seal the stay lower end vents (usually 3/32") and the seat stay upper vents preventing water from getting in by those points. I leave the shell vents open and at least 1/4" in diameter. I also vent the shell to the outside at it's low point, again a 1/4" hole.

While I do vent the top tube at both ends, again 1/4", I don't do any unusual steps to keep water out other then making sure the post and headset are well lubed. But I don't ride much in the salty winter and I pull my post a couple of times a year usually.

Prior to sealing the stay vents I make sure the flux has been flushed out and the tube is dry inside. No other effort or application before the brazing closed, where I try to use as little flux inside the hole. I'm of the mind that a dry tube won't have much interior rust develop over the years. The handful of my frames that I've cut apart bears this out.

I deliver a frame to a painter as dry and bare as I can get it. (I will apply a wiping of Navel Jelly on the outsides to reduce the surface rust while waiting for paint prep. This is a phosphate solution similar to what many painters apply to the clean frame just before primer). No interior anything. Full disclosure about vent hole locations. After paint I will apply Frame Saver to any interior that I can. Andy.

[Rody]

I'm of the mind that a dry tube won't have much interior rust develop over the years. The handful of my frames that I've cut apart bears this out.

Based on many years of doing restorations on Fat Chance frames and later, early IF's, sealed tubes still allow condensation to slowly erode away from the inside out. Top tubes, downtubes, stays...seen it all at least 100 times and replaced the tubes to fix it.

Make nice big vent holes, use some LPS Rust Inhibitor annually, and most importantly...treat your steel frame nice.

Rody

[Paul Jacobs]

As I understand it, it is oxygen which causes rust not moisture. The water just facilitates the reaction. The argument is that, by sealing the tubes (which is possible for top tubes and seat stays with lugged frames) any oxygen inside will get used up and then the rusting process will stop. I think the problem with this is being certain that a tube is sealed. A "sealed" tube which is leaking somewhere is clearly worse than a tube with holes big enough for it to dry out and big enough for rust inhibitor to be introduced.