Water inside a steel frame.

Water can enter a bicycle frame from many points. Some of the more common points where water can seep in are around the seat post, headset, handle stem, and water bottle bosses. Many builders provide drain holes at the bottom of the fork tubes, in the seat stays near the rear dropouts and at the bottom bracket to allow accumulated water to drain out. Another way water can get inside is through condensation. Even if you don't ride in the rain, moisture laden air finds it's way into a frame. Then, temperature changes can cause that small amount of moisture to condense on the inside the tubes. As the process repeats itself,  a corrosion or rust problem can gradually develop. When a bicycle has couplings, that's another potential point of entry. 

To prevent moisture from getting past the couplings and into the inside of your frame tubes, we provide builders with very thin stainless steel discs that can be inserted in the coupling before the coupling is brazed onto the tube. Once the coupling is brazed in place, a seal is created between the end of the tube and the disc. The disc then prevents any water that might enter through the couplings from reaching the inside of the frame tubes. Moisture contained in the stainless steel coupling won't damage it in any way. 

The left coupling is shown without a disc.     The right coupling is shown with a disc.
These images of a cutaway coupling shows how a disc blocks the end of the tube to keep moisture out.

Some builders prefer to not use the discs. Since water will enter at other places in addition to the couplings, their theory is that it's better to leave the coupling open so water that enters the frame at other places above the coupling, can drain down through the coupling to the bottom of the frame where it can escape. 

Some cyclists don't want the discs because it blocks the area inside the tube which can be used to store seldom used items and emergency parts such as spokes. Not having discs also makes inspecting the inside of the main frame tubes possible so you know if there is a moisture problem or not. If the discs aren't used, a cork or rubber stopper can be used to block the hole.

On a frame made with or without discs, we recommend coating the inside of the frame with J.P. Weigle Frame Saver. It comes in an aerosol can and can easily be applied through the hole in the center of the coupling.

Out of Sight, Out of Mind - Rust Never Sleeps 
by Peter Weigle

Steel frames rust, that's all there is too it. They rust when scratched, chipped, or abraded in any way. Most people know this. What they don't know is that steel frames also rust from the inside out. That's why I am so amazed that manufacturers go through great pains to paint the outside of a frame but the completely ignore the inside surfaces of the steel tubes. The steel inside the frame is almost always left raw and unprotected. If a little moisture enters the frame, the environment within will resemble a terrarium. The humid air and water droplets will be attacking the steel and you won't even know it. Left untreated, the frame will be destroyed.

To help prevent rust inside steel tubes, Frame SaverŪ was developed. It is a product that was long overdue. It coats the inside of the steel tubes protecting them from the corrosive elements that find their way there. 

True, bicycles have been around for 100 years and there are plenty of early examples of frames that have lasted lifetimes without rust, so why all the fuss now? Because in the last couple of decades there have been major changes in materials, equipment, and bike usage that have made internal frame protection even more important.

Today's high performance frames are being made with extremely thin walled tubing compared to frames of the past. There used to be a safety margin should the tubes rust. Not any more! There are a few construction details found in some frames that have trapped water and caused premature failures. Frame builders who do repair work, painters and mechanics, are seeing a higher incidence of rust-throughs these days, and it is only going to get worse, unless these frames are rustproofed on the inside. Most new bikes are equipped with sealed bearings, which mean fewer overhauls and fewer chances to look in the bottom bracket to see what is going on. After many carefree miles, many mechanics and owners are shocked when they pull the bottom bracket bearings and find rust-colored sludge, or flakes of rust, inside the shell. Hopefully, it's not too late to save a frame in this condition.

Mountain bikes are supposed to be used in extreme conditions. Stream crossings, fall, winter, and early spring rides all involve, among other things, water.

Even if you don't ride in the rain or cross raging rapids, moisture still finds its way into a frame. Take your bike out of a warm house on a cool, damp day, or on a hot day return your bike to a cool, damp basement for storage and what happens? As the warm air inside your frame cools and contracts, it pulls in the damp air past the seat post, threads, and vent holes. This may only be a minute amount, but do this many times over the course of the season and the cumulative effect can be devastating.

It would be misleading to suggest that every steel frame is a risk because there are many factors involved. It is impossible to tell from the outside, which frames are screaming for attention. Why take a chance? With the cost of bikes these days, think of it as cheap insurance. Prevention is easy. An application of Frame SaverŪ will add years to a frame's life and peace of mind to its owner. May you both ride happily into the next millennium and beyond.

Another option that some people like is to completely seal off the entire coupling from the outside. Making a sleeve that can be stretched over the couplings from an old inner tube or condom works great for that purpose especially if the bike is being ridded off road in the mud or in the rain. To keep mud off the couplings, Lizard Skins will also work. The are made of very thin wet suit type fabric backed foam material with hook and loop on both sides for easy removal. Lizard Skins are available in bike shops.

If your bike wasn't built with the stainless steel discs, it is possible to use silicone seal to hold a small plastic disc or plug in the end of the coupling which should prevent moisture from getting into the frame yet it can still be removed if it becomes necessary to inspect the inside of the frame. Even a cork or rubber stopper inserted into the hole in the end of the coupling would work as long as it doesn't stick out to interfere with the coupling teeth. 

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