Author Topic: Dealing with rust / refinish  (Read 822 times)

Dealing with rust / refinish
« on: April 25, 2021, 06:35:34 pm »
My touring bike is about 15 years old now. There are a few places with very minor bubbling below the surface, but one place where there is more rust - the chainstay bridge where the mudguard mounts. I guess this is an area where water gets in under the mudguard clip.

A few pics (linked to biggies):









I'm thinking of getting the frame powder coated. I'm assuming this rust isn't so bad that it won't get taken care of when they blast it? Or is it? I'm sure the more minor stuff will be no problem, it's just the above that I'm a bit worried about.

I did spray (thinned) Waxoil inside the frame when I got it, so I'm hoping all is good internally. If it isn't - how on Earth can you tell anyway?!

Any thoughts much appreciated.
Those wonderful norks are never far from my thoughts, oh yeah!

Re: Dealing with rust / refinish
« Reply #1 on: April 26, 2021, 11:59:57 am »
That is bad - what would bother me more is the thin line on the BB/chainstay join in the third picture.

I'd go for an aggressive wire-brushing off of the rust on the chainstay, and pick at it with a small screwdriver, really dig into the pits.
<i>Marmite slave</i>

Re: Dealing with rust / refinish
« Reply #2 on: April 26, 2021, 12:34:10 pm »
Hmmmm... You think it needs to go to a frame specialist for repair?
Those wonderful norks are never far from my thoughts, oh yeah!

LittleWheelsandBig

  • Whimsy Rider
Re: Dealing with rust / refinish
« Reply #3 on: April 26, 2021, 12:38:04 pm »
Chainstay bridges don’t do very much to strengthen a frame. That said, I would look very hard at the bridge’s corrosion as potentially the corrosion could be penetrating into the chainstays themselves out of view within the bridge (unless you squirted something into the bridge years ago).
Wheel meet again, don't know where, don't know when...

Re: Dealing with rust / refinish
« Reply #4 on: April 26, 2021, 06:03:47 pm »
Chainstay bridges don’t do very much to strengthen a frame.
They do if the chainstays are long, making a stiff box at the back with the hub on the opposite side (according to Tony Oliver"s book, anyway).  Not so much on racing bikes, which don't necessarily have one at all, if they have vertical dropouts or track ends.

The bridge actually serves three purposes:

1. Stiffness where the stays are long, as on a tourer
2. Somewhere to bolt a mudguard
3. Stops the tyre jamming when you remove a wheel with forward-facing dropouts
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

LittleWheelsandBig

  • Whimsy Rider
Re: Dealing with rust / refinish
« Reply #5 on: April 26, 2021, 06:09:53 pm »
I don’t think Mr Oliver did FEA of his frames. The bridge adds a bit of stiffness but adding the same amount of steel to the stays is at least as efficient. The other reasons are worthwhile on their own though.
Wheel meet again, don't know where, don't know when...

Re: Dealing with rust / refinish
« Reply #6 on: April 26, 2021, 06:32:58 pm »
Hmmmm... You think it needs to go to a frame specialist for repair?

I think that you won't know until you try poking holes in it with a little screwdriver.

If it is sound, you won't succeed and will have just dug out rust.

If you do, I think it needs a framebuilder.
<i>Marmite slave</i>

Re: Dealing with rust / refinish
« Reply #7 on: April 26, 2021, 06:40:53 pm »
Back in 2005 I stripped my old MTB and repainted it in hammerite.   According to the post it was ~20 years old at that point.
http://www.nuttycyclist.co.uk/cycling/oldmtb-restore.htm

I still use that now as a shopping bike, and it looks not much worse than it did in those photos and much better than it looked before I started work.

Re: Dealing with rust / refinish
« Reply #8 on: April 26, 2021, 08:42:03 pm »
Chainstay bridges don’t do very much to strengthen a frame.
They do if the chainstays are long, making a stiff box at the back with the hub on the opposite side (according to Tony Oliver"s book, anyway).  Not so much on racing bikes, which don't necessarily have one at all, if they have vertical dropouts or track ends.

The bridge actually serves three purposes:

1. Stiffness where the stays are long, as on a tourer
2. Somewhere to bolt a mudguard
3. Stops the tyre jamming when you remove a wheel with forward-facing dropouts

From personal experience I would disagree with n°3. My Gitane with forward-facing dropouts and no chainstay bridge is an absolute dolly to get the rear wheel in and out, especially compared to my other frames with bridges. The worst is the vintage Peugeot Corse which is an absolute pig. It is a racing frame so the mudguards issue doesn't come into play.

I don’t think Mr Oliver did FEA of his frames. The bridge adds a bit of stiffness but adding the same amount of steel to the stays is at least as efficient. The other reasons are worthwhile on their own though.

I think, depending on the frame builder, it serves only as a mudguard anchorage point; the Gitane seems plenty stiff enough and it's only a lower end industrial production racing frame. Eliminating the bridge does eliminate  a potential mudtrap however, which is probably a valid arguement on a tourer - other ways can be found to anchor that end of the mudguard.

Re: Dealing with rust / refinish
« Reply #9 on: April 26, 2021, 09:32:24 pm »
....what would bother me more is the thin line on the BB/chainstay join in the third picture.

I'm not sure where you mean. Maybe A or B? Or something my eyes are too shit to see?!

[Big pic]

Those wonderful norks are never far from my thoughts, oh yeah!

Re: Dealing with rust / refinish
« Reply #10 on: April 26, 2021, 10:10:45 pm »
Have you goat a powder coater in mind?  A decent one with cycle experience will give it a good look between removing the old and applying the new.  I recently had a frame done in Maldon, not the cheapest, but seem to know what they're doing and they say they'll examine and report if there's any reason not to proceed
https://ctc-powder-coating.co.uk/our-work/bicycles/

I'm a bit wary of that much rust anywhere, I try and catch it before it gets to that point, yet I've seen some frames looking a lot worse resurrected and last years.

Re: Dealing with rust / refinish
« Reply #11 on: April 26, 2021, 10:36:00 pm »
Have you goat a powder coater in mind?  A decent one with cycle experience will give it a good look between removing the old and applying the new.  I recently had a frame done in Maldon, not the cheapest, but seem to know what they're doing and they say they'll examine and report if there's any reason not to proceed
https://ctc-powder-coating.co.uk/our-work/bicycles/

I'm a bit wary of that much rust anywhere, I try and catch it before it gets to that point, yet I've seen some frames looking a lot worse resurrected and last years.

Funnily enough, the Maldon lot are the closest powder coaters to me, so that is where I would take it. I'll probably strip the whole frame down later in the week, take some more pics and send them over to them to see what they say. I did notice on their website that they mention rust/repairs, so I'm sure they can sort out any problems - or at least get someone to sort them before proceeding...
Those wonderful norks are never far from my thoughts, oh yeah!

Re: Dealing with rust / refinish
« Reply #12 on: April 30, 2021, 07:24:02 am »
....what would bother me more is the thin line on the BB/chainstay join in the third picture.

I'm not sure where you mean. Maybe A or B? Or something my eyes are too shit to see?!

[Big pic]


I meant A

Could be nothing - but the enamel having a break in a line is sometimes a sign of flexing - in this case where there shouldn't be flexing.

If I were you I'd carefully remove the paint there to investigate.
<i>Marmite slave</i>

Re: Dealing with rust / refinish
« Reply #13 on: May 03, 2021, 08:52:44 am »
My steel framed bikes were protected internally by phosphoric acid treatment before assembly.  All are 'old' bikes - 1987, 2000, 2003

The 35 and 21 year olds were re-enamelled by Ellis Briggs a few years ago and passed their inspection as rust-free internally.

Only one of my steel bikes has ever failed. A radial crack in the downtube.  The crack appeared months after I was T-boned and started where there was a tiny dent from the impact, nothing to do with rust.  I found it when there was mystery creaking noise under pressure.  I rode it home very carefully for about 50km.  It was an off the peg frame from the mid-80s of mid-range quality.

In my view you need a professional frame builder to assess a steel frame if there is any doubt.  I'm not a fan of powder coating unless it is a hack bike.
Sic transit and all that..

Re: Dealing with rust / refinish
« Reply #14 on: May 04, 2021, 09:43:45 am »
I meant A

Cheers. I gave it all a good clean up and A was mostly dirt and it's now gone!

I'm not a fan of powder coating unless it is a hack bike.

It's a Surly which are all powder coated from the factory, so seems logical to get it redone the same. Anyway, it's a touring bike that takes a lot of abuse so wouldn't want a fancy paint job!

I have just phoned Maldon Powder Coating and am taking it down there this morning. I've explained everything and they will check it over and can do any repairs if needed. Fingers crossed!

I think I shall go for this colour:

Those wonderful norks are never far from my thoughts, oh yeah!

Re: Dealing with rust / refinish
« Reply #15 on: May 04, 2021, 10:54:27 am »
I think I shall go for this colour:
That was on my shortlist, though I already have a grey bike.  Have you checked the colours they have in stock?  They didn't have my first or second choice, in the end they sent me their stock list so I could pick something they did have, it's a bewildering choice and it took longer for me to decide than it did for them to paint it!
I went for RAL 6011

Alfie by Paul, on Flickr

Re: Dealing with rust / refinish
« Reply #16 on: May 04, 2021, 11:56:09 am »
Nice  :thumbsup:

Just got back. They weren't sure if they had the colour I wanted in stock and did say they could order it in at additional cost. Then some bloke came into reception and reckoned they did have some. He then said if they didn't they'd just get some in and not charge me for it (which caused grumbles from the woman on reception). Either way, I'm having that colour and it will be done in a month or so. The bloke said they'd give the frame a thorough inspection and the rust on the chainstay bridge (which I'd cleaned up further) didn't overly concern him.

Can't wait :)
Those wonderful norks are never far from my thoughts, oh yeah!

Re: Dealing with rust / refinish
« Reply #17 on: May 05, 2021, 09:16:16 am »
That's a good colour for a tourer.  Nothing too ostentatious. The only bike I have had nicked was bright red.
Sic transit and all that..