aeroemike

Let me start by saying that I'm pretty new to cycling and wanted to give it a try. I recently bought a bicycle used that was in pretty good shape. It has a steel frame. I noticed that the screws where a water bottle mount would go were missing. I then noticed the threads had some rust on them. It seems to me that with the screws missing, water could have very easily gotten inside the frame. If this is the case couldn't there be a significant amount of rust inside the frame? I'm not sure if I'm being paranoid or if this is a genuine concern. What are your thoughts?

Retro Grouch 

I wouldn't worry if everything else looks OK - no bubbling paint for example. Some air circulation inside of the frame is actually a good thing. While rust is a fact of life, bike frames that are made with higher quality steels (look for a tubeing sticker on the seat tube), are pretty rust resistant.

The bottom line is that I don't do anything special to the inside of my bike frames and I've never owned a bike frame that didn't last longer than I wanted it to last.

aeroemike

The frame is a surly crosscheck. The website says the steel is surly 4130 cro-moly steel. Is this a very rust resistant steel? Would rust on the screw threads indicate rust inside the frame, or are the threads general a low quality steel?

Jed19

4130 Cro-Moly is, maybe, a little tad better than iron pipe. It is not the best grade of steel alloy, nor is it the worst.What I'll advise you to do is to strip the bike of all components and treat the interior of the tubes with a good anti-rust. If you do a BikeForums search, you'll find out what others have suggested as good anti-rust treatment(s).

In my view, it does not matter what kind of steel alloy you have, it will eventually develop some rust, albeit things depending on different environmental factors and the length of time involved. Rust develops on steel and steel alloys because of chemical reaction between the iron in the steel and air.If the air is really moist (at sea, or sea shores), then a "rust bucket" can and will result very very quickly. And as long as you have oxygen in the air, the tendency is for steel to develop rust, thus the need to apply anti-rust agents to the innards of steel tubes made into bike frames.

Think of things this way. If the rust on the screw threads are the only rust on the frame, then you'll have nicked things in the bud, before things get ugly. If however, the innards of the tubes have rust, then you can think of your anti-rust treatment as something that was long overdue, but had been overlooked.

Good luck.

Regards,

MichaelW

There are 2 ways to prevent the tubes rusting internally, a water drainage hole underneath the bottom bracket and a coat of some rust inhibitor.
There is some official bike tube strap (Framesaver) but I have used WD40 with a lot of success. My bike lived outdoors 24/7 for 2 years in a damp coastal town.
Check the style of your BB shell. Is it a simple section of tubeing or does it connect internally to the other tubes? If there is a connection, then water may gather at the base and a small drainage hole will allow water to escape.

Deanster04

Framesaver from Weigle. Will prevent further corrosion. A little rust isn't bad.

Deanster04

Framesaver from Weigle. Will prevent further corrosion. A little rust isn't bad.

jbrians

ANY aerosol (spray) can of oil, whether it be from Gunk or even (gasp) WD40, will give you way more rust prevention than you will ever need.
Give it a good squirt in every drainage hole on every tube and you will be good to go for about 100 years.

Hambone

and then jiggle it around. Like you were shake and baking a pork chop.

spunkyruss

I posed the question "Have You Ever Seen a Frame Fail from Internal Rust? " in a recent thread. The consensus was that it's rather rare under normal circumstances.

robhunterx

Based on my limited education on engineering materials, rust will occur 1st on the threads because of the inherent shape and because of the concentration of stresses there during the threading process. With that said, the responses you have received above on how to protect the frame from the inside are right on and I predict your frame will last a very long time and never let you down due to corrosion.

Hambone

one of the few funny scenes in Friends...

Mr. Greene (Rachel's dad): "Rust is like cancer to a boat."
Ross: "Rust... I lost a bike to that."