rusted frame studs

[Dunkgrease]

We have owned two Thorn Nomad bikes with SS couplings and have now covered in excess of 35,000km in the last five years.

During this time the bikes have a taken a lot of hammering, being loaded onto trains, boats, buses,trucks, etc as well as the normal day to day cycling.

They have been scratched a lot so last year when I was in the Philippines I decided to have them resprayed.

On one of them the lower mounting boss for the bike bottle cage (the one on the underside of the tube from pedals to head stock was so badly rusted that it had become detached, leaving a ghastly rusted hole in the frame. The spray shop did a great job.  Welding the stud back in place,  filling and painting in the same original colour.

All has been well until this year. I realised that the stud on the other bike was also rusting through.  We are now in Portugal and wondering what to do about it.

It seems to me that there is a fundamental problem with the design.  Water ingress in the headstock tube runs down the inside of the sloping frame tube.  Due to the SS coupling at the base of the tube there is no way for any water to drain out.  So it collects in the bottom of the tube causing it to rust badly.

Has anyone come across this before and or know if Thorn flagged it as an issue?

thanks

Steve

[julk]

Not an answer, but the handmade ‘exp' types were made with sealed frame tubes, maybe to remove this possibility.

[jags]

that doesnt sound good steve, as far as i know my audax 853 is sealed on the inside and my screws are stainless so hopefully i wont be suffering that problem.mind you it wont be getting the kind of cycling you do  lives indoors treated like a baby..

why not get in contact with sjs find out if this was a design problem.


jags.

[phopwood]

You have the age old problem of rusting from the inside out, the rust you are experiencing will be worse on the inside of the tube.   I think your water is getting in via the head tube, or the bolts on the lower water bottle boss and collecting at a certain point.

Remove you forks, or loosen them enough to have a look down the hole, is it rusty,  are there holes to the down tube, if so this most likely the problem, you could flow some rust proofer though the tubes to make stop it getting any worse and then block off the hole with some tape.

With rust prevention is better than the cure.

I had some water collecting in my bottom bracket and it turned out to be getting in around a loose bolt in the lower water bottle boss, just where the road spay got to it.


Peter

[mickeg]

I bought my S&S Nomad a year ago.  There was a piece of tape installed inside the head tube that covered the holes to the down tube and top tube.

I treated the frame with Weigels Frame Saver before I assembled the bike, thus I removed the tape to allow the frame saver to get into the top and down tubes.  After that I put a new piece of tape over the holes inside the head tube.  I have no idea if the tape will effectively seal off water ingress into the tubes, but in my case the Frame Saver should help limit or slow down the rusting process.

I recently changed forks, twice.  Your posting reminded me that I should have inspected the tape to make sure it still covers the holes while I had the fork off of the frame, which I did not do.

On a different bike with a derailleur, I drilled a tiny hole through the small bolt that holds the plastic cable guide under the bottom bracket to create a drain hole.  (And I busted the drill bit in the first bolt that I tried this on.)  Not sure if that would be a very good solution for a Nomad water bottle cage bolt, you could still have a lot of water in tube since the bolt would be several cm higher than the bottom, but that would create an upper limit for how much water can accumulate in the tube. 

Unless you regularly ride down steep hills, the top tube could suffer the same fate.

[Znook]

Thanks for the input Mick - the OP didn't say if their frame is a Mk1 or 2 so I was wondering what it'd be like on the current version as this will be the one I'll be going for.

Can anyone post a pic of where the water gets in to the downtube - would love to see this if possible.

Cheers,
Robbie.

[mickeg]

Thanks for the input Mick - the OP didn't say if their frame is a Mk1 or 2 so I was wondering what it'd be like on the current version as this will be the one I'll be going for.

Can anyone post a pic of where the water gets in to the downtube - would love to see this if possible.

Cheers,
Robbie.

I do not have a photo.

Look in any bike head tube and you can see that there are holes into the interior of the top and down tubes.  Thus, if water gets past the headset bearings, it could get into the top and down tubes.  The down tube is steeply sloped so water would never flow back up hill and out the head tube.  There are small disks inside the S&S couplings that keep the water from flowing out past the coupling.  Since the Nomad has a pretty steeply sloped top tube, water could also accumulate there unless you frequently rode down very steep hills.

If I had not seen the tape, I would not have thought about it.  And I would not have seen the tape if I had not been treating the inside of the frame with a rust proofer because I would not have looked for it.

I suppose it would be possible to drill a tiny drain hole through the lower most part of the disk in the S&S coupler.  But that is more effort than I care to do.  I also do not know if that would solve anything because if the S&S coupler tightens up to be water tight, that might only allow water to accumulate in one more location.

I do not know if this is an issue on non-S&S bikes.  If water that gets in the down tube is free to flow into the eccentric shell (bottom bracket) this would not be an issue since water would readily drain out before it could accumulate in the down tube.

[Donerol]

IME water gets into the head tube via the stem and the spacers. The stem is hollow - the rain lands on the handlebars, collects in the gap behind the front plate, seeps behind the bars and down the stem and onto the steerer tube. If you have a stack of spacers then driving rain gets between them. Some of the water trickles down the tubes if they are not blocked off, and the rest accumulates at the bottom of the steerer.

When I first got my Audax Mk3 a few years ago, I was surprised that the steerer was bare metal, without any primer, and the instructions said that it should be left bare. After the first wet ride I had a nice trickle of bright orange all the way down the forks. I rang Thorn to query this and they said just keep an eye on it, and drop the forks out once a year to inspect them. After a month and more orange trickles I took the forks out with some difficulty. The steerer had rusted so badly that the spacers were jammed and I needed to tap it out with a mallet. I should have taken a photo of it and the pitting that had resulted. Anyway, I cleaned the rust off, applied Kurust and then Waxoyl before reassembling. The other tubes had been taped over with masking tape so the water hadn't got in there.

I also bought a s/h Raven last year. The steerer had also rusted but not so badly, being 531. However the top and down tubes were open where they met the head tube, and there was quite a lot of rust inside them. I applied a lot of thinned waxoyl, then closed the holes with some tarry tape (intended for roof repairs, I think - I will put this tape on the Audax soon). I also used Kurust and Waxol on the steerer, applying it generously so that it squidged out between the spacers in the hopes of reducing water ingress.

For both bikes I have made cork plugs from sparkling wine bottles, inserted into the stem just behind the bars and with plenty of grease, to try and stop water getting in.

I am not getting at Thorn, though some makers do put a decent amount of primer on their steerers. But I think it is a fundamental weakness in the threadless design that a lot of people aren't aware of. Recently I stripped down a 35-year-old 531 frame that has been used regularly in all weathers. The 'threaded' headset needs new ball bearings but the steerer tube is immaculate.