Rust inside xTc seat tube

[loh]

Hello there,

I purchased a second hand xTc shortly before Christmas. Due to a bout of illness followed by the holiday period I wasn't able to give it as thorough out-of-the-box inspection as I would have liked (it's been in storage since checking the basics). The bike seems in good general condition and rides beautifully (fitting like a glove). I've recently been making a few adjustments and touching up some superficial paint chips and surface rust following suggestions from the forums (kurust / red oxide primer / humbrol). However, when examining the inside of the seat tube using a torch I was alarmed to see a significant amount of corrosion and surface rust. This seems to begin below the level of the seat post, getting progressively worse towards the bottom bracket shell. The seat post is also a little stiff (scratchy) to adjust as the inside tube surface is coarse (although not rusty) in the top part of the tube. The front right-hand side of the bottom-bracket cartidge also shows quite a bit of surface rust, although without removing it (I don't have a tool handy) I'm not sure if it's debris that's dropped from the tube, or rust on the cartridge itself. There also appears to be some raised corrosion around the point at which the front derailleur attaches to the tube (the corrosion mostly looks metallic in colour). I have no problem removing the screws from the seat tube bottle cage, or from the drain hole on the bottom of the bottom bracket shell (they also show no external corrosion).

Should I be worried by this? I've searched the forum for advice and was concerned to see a seat tube rust-out on another xTc (the exterior condition of my frame appears to be far better than this though). I am a little miffed since the shop from which the xTc was purchased had indicated that the bike had been fully serviced. Presumably the rusty bottom bracket would have been obvious if it was removed in order to regrease the threads (I assume that this wasn't part of their service). I guess I'm going to have to remove the bottom bracket and clean out the seat tube and bottom bracket shell in order to assess the damage (maybe using some kind of flex-hone for the tube). I've got some spare waxoyl somewhere so I'll try to give it a good coating with that. Sadly I'm short of time and tools at the moment so I'm hoping I can get a friend to help me in the near future.

Let me know if there are specific things that I should look out for or test. One thing I'm now worried about is that bad rust spots on the inside correspond with some of the small ones that I've touched up on the outside. I've tapped the length of the tube and there aren't any obvious changes in thickness or soft patches. Hopefully it's nothing too serious...

I've attached couple of photos from my camera phone. Unfortunately it's hard to focus on the bottom of the tube, which is where the corrosion is most severe.

Cheers.

[loh]

Over the weekend I had the chance to examine the seat tubes of a few other old steel framed bikes at a friend's house. These have been left outside for years in a pop-up gazebo type thing that is rather damp in winter and humid in the summer time. While the frames show a lot of pitting and surface rust on the outside there is very little in the inside of the seat tubes, and what is there seems light and wispy (it can mostly be brushed off with a finger). In addition, the interior of the seat tube is smooth to the touch. In contrast the inside of the xTc tube is extremely coarse and looks like it's covered in burrs. It almost as if the frame builder forgot to hone it and the additional surface area has resulted in a significant amount of oxidation.

[jags]

yip that looks bad best get it checked with a frame builder .

[Danneaux]

Should I be worried by this?

Well...it doesn't look *good*, but it may not be so bad as it first appears.

I would suggest removing the bottom bracket and taking a look up from below.

A handy tool I recently tried (and will soon buy) is a lighted borescope attachment for my smartphone. The little camera snakes into confined places and produces a display on the phone. The one I tried was only about USD$15 postpaid. Not bad.

Lacking that, I think I'd remove the bottle cage bolts on the seat tube and probe lightly with a spoke to see if the steel appears soft. That will tell you a lot right there.

So sorry you're having to deal with this, loh; what a disappointment on a new (used) purchase!

I'd try to use a wire "bottle brush" to remove as much loose rust and scale as possible and see how it looks from there. So long as the seatpost doesn't slip, the coarse interior near the top may not be so problematic. I'm more worried about what I see at the far end of your photos, down near the bottom of the seat tube/top of BB shell.

Please keep up updated as your explorations progress. All best wishes and fingers crossed for your good luck going forward,

Dan.

[loh]

Thanks for all the helpful suggestions. From an initial internal exploration via the bottle cage holes the surface looks to be sound (at least the parts of the opposite side that I can reach). I'm still keen to remove the bottom bracket so that I can properly investigate the rust towards the very bottom of the seat tube. I should be able to get a hold of some tools fairly soon (mine are in storage) so I'll report back after that.

From what I've seen so far, it looks like the pronounced rust might (here's me be hopeful) simply be a result of the poor finish on the tube interior, i.e. the coarse finish providing a much larger surface area for oxidation. I've not seen (or felt) a tube like this before: is this a common occurrence? I assume that tubes are usually honed after reaming to remove left over burrs and whatnot. I've also seen some reports of residual brazing flux being left in tubes, but this seems pretty rare.

[loh]

Being unable to source a reasonably priced flex hone in the UK I decided to fashion my own makeshift tool using a piece of dowel and some sandpaper. The good news is that the majority of the surface gunk came of pretty easily and the metal looks relatively clean and shiny underneath. The bad news is that the surface rust appears to be (or on top of) a sticky greasy substance, so I'm wondering if I've actually spent my time simply removing some kind of frame saver from the tube.

I've read that frame saver (and waxoyl) can dry to a somewhat sticky brown coating. However, the few freshly prepped steel frames that I've seen before had a protective coating with a fairly uniform honey colour (certainly not with orange spots). In my case the coating was very uneven, both in texture and colour. I've not yet removed the bottom bracket to assess things there, but it was possible to wipe off most of the orange coloured residue that was on top of the cartridge using a rag attached to the dowel. I'm wondering if some badly applied frame saver dripped onto the shell, perhaps when the waxy substance became warm on a hot day. The other possibility is that the rust has simply mixed with a bunch of grease that was inside of the seat tube (which has slowly worked it's way down the tube over time).

Does anyone have any ideas? It seems daft for a rust inhibitor to dry to a colour that looks like rust (especially if it also has a very uneven colour and texture). Even if I have just wasted an afternoon I'm sure that I could do a better job with a recoat. I'll be able to get around to that once I've removed the bottom bracket and cleaned out the shell.

Cheers.

[Bill C]

have you tried just washing it out with paraffin?
i use a long bit of threaded rod,
 tightly cable tie some pan scourers to it push it down the seat tube making sure it has enough slop/free play to not get stuck down there,
pour some paraffin into the seat tube soaking the scourers and just pump the rod up and down and spin it as you do, it will soon dissolve the old grease and any wax
once you've done that i'd remove the rod squeeze out any paraffin then repeat the process with clothes washing powder in hot water, that should remove any traces of paraffin and grease
then dry it out either naturally or with a air line, once it's dry you can repeat the whole process with phosphoric acid or your chosen rust remover (hammerite rust remover gel is gentle on paint but eats rust)
leave the gel/acid to do it's work, you can rinse and dry it and repeat the rust remover till it looks clean and a uniform dull grey down inside
once you get it to that stage dry it out and add your preservative of choice, there's plenty of recipes online for diy waxoyl

i wouldn't use a hone or anything to aggressive for fear of removing good metal
surface rust always looks bad, my nos bare metal xTc looked pretty grim when i got it but came up lovelly in the end hopefully it's not deep pitting

[mickeg]

Being unable to source a reasonably priced flex hone in the UK I decided to fashion my own makeshift tool using a piece of dowel and some sandpaper. The good news is that the majority of the surface gunk came of pretty easily and the metal looks relatively clean and shiny underneath. The bad news is that the surface rust appears to be (or on top of) a sticky greasy substance, so I'm wondering if I've actually spent my time simply removing some kind of frame saver from the tube.
...

I am in USA so I often use different terminology.  I used Framesaver on several of my bike frames, it sprays on and forms a soft solid sort of coating that is similar to the color of rust.  I used coleman fuel (camp stove fuel that I think some Europeans refer to as benzene) to clean any off that I did not want.  It dissolved readily.  But it is flamible, if you use anything like that use it outdoors where there are no ignition sources.

Suggest you avoid sanding too much on the part of the frame where you grip the seatpost so that it will still grip it tightly.  Other than that, I can't imagine that using any sanding type of device on the end of a stick that you operate with muscle power could possibly remove too much metal.  It would require a lot of metal removal to impact structural integrity. 

A few years ago I bought an old Bridgestone bike that had been stored outside for over a decade.  Quite rusty, but I applied framesaver to it and continue to ride it.  And I store it outside.  I made sure that the frame was quite dry before I added any new framesaver to it.

[Bill C]

loh
is this the type of flex hone you were on about? remember that seat tube is pretty thin metal 
  https://www.youtube.com/watch?v=EB6_IuaRXYs are they long enough to reach the bottom of the seat tube?

mickeg

if it were my bike i'd want to remove/kill the rust rather than just adding more framesaver over the top
but then i'm probably a bit anal about my redo's

round here a steel bike stored outside wouldn't last a decade and still be rideable,
wish i had your climate  it must be like a desert

[Javier]

One of my colleagues was commuting riding his proudly and trusty father's old bike when the fork snapped and he landed on his face. He had to go to the hospital with a serious concussion, followed by a number of plastic surgery sessions for about one year.
I would not ride a bike if I have reasonable doubts about its integrity, it is not worth the risk.

[loh]

Thanks for all the replies:

is this the type of flex hone you were on about? remember that seat tube is pretty thin metal 
  https://www.youtube.com/watch?v=EB6_IuaRXYs are they long enough to reach the bottom of the seat tube?
...

Yes, that's the one. You can buy an extension shaft for a drill which allows you to reach the lower part of the tube. When I lived in the US they seemed to be a pretty common tool in bike workshops (some even sell them). You just use them for a short while at low RPM in order to clean out the tube. Over here in the UK you can only seem to find these three-pronged brake cylinder hones, which are much more aggressive.

I used Framesaver on several of my bike frames, it sprays on and forms a soft solid sort of coating that is similar to the color of rust.

Interesting, that's good to know. The colour in my tube was pretty uneven so it really did look like rust spots (the surface looked coarse too). I'd love to see a picture of tube with Frame Saver or Waxoyl appplied so I that could compare it to mine. That said, I guess it depends on all kinds of factors (how thick it was applied, temperature, age, ...) so there would probably be a lot of variability. I wonder whether the sticky residue that I was seeing on the sandpaper was simply seat tube grease mixed with the rust that I had removed. Perhaps I should develop a line of custom (non-rust) coloured rust inhibitor. That way it would be easy to tell what's rust and what isn't (especially when buying a second-hand bike). 

Suggest you avoid sanding too much on the part of the frame where you grip the seatpost so that it will still grip it tightly.  Other than that, I can't imagine that using any sanding type of device on the end of a stick that you operate with muscle power could possibly remove too much metal.  It would require a lot of metal removal to impact structural integrity.

Yes, it was just a light sanding by hand. No problems with the seatpost, it still fits snugly and grips tight.

One of my colleagues was commuting riding his proudly and trusty father's old bike when the fork snapped and he landed on his face. He had to go to the hospital with a serious concussion, followed by a number of plastic surgery sessions for about one year.
I would not ride a bike if I have reasonable doubts about its integrity, it is not worth the risk.

I totally agree. This was the purpose of the exploration: I wouldn't have been happy riding the frame long-term without being confident in its structural integrity. The tube interior is starting to look really good, so (despite possibly having removed a useful rust inhibiting layer) I'm now a lot more confident in its longevity.

[mickeg]

...
mickeg

if it were my bike i'd want to remove/kill the rust rather than just adding more framesaver over the top
but then i'm probably a bit anal about my redo's

round here a steel bike stored outside wouldn't last a decade and still be rideable,
wish i had your climate  it must be like a desert

No, but probably not as wet as the UK.  Probability of precipitation on any given day varies from 40 to 60 percent.
https://dbffkv15yp72v.cloudfront.net/production/reports/year/000/030/954/345e672/probability_of_precipitation_at_some_point_in_the_day_percent_pct.png

Some steels appear to hold up much better against rust than others.  On this bike it took a LOT of effort to get the old bottom bracket out, the rust on the threads did not help much.

First photo when I first bought it.  Second photo after I cleaned it up and regreased all bearings, new chain and lots of other new parts.  Third is how I store it in winter.

[Bill C]

mickeg

whats all that white stuff in the 3rd pic?

do a search for Lynton/Lynmouth flood and Boscastle flood, i'm lucky i live in between the 2
pic from across the river last year, it's the high street

[mickeg]

mickeg

whats all that white stuff in the 3rd pic?

do a search for Lynton/Lynmouth flood and Boscastle flood, i'm lucky i live in between the 2
pic from across the river last year, it's the high street

The white stuff, we call that snow up here in the north country.

[alfie1952]

The cyclist is obviously not bothered about getting his hub bearings and pedals wiped  out. Hopefully not riding with Rohloff !