Problems with rust and drivetrain
 

Hello, I recently bought 1988 Miyata 615 for $210 CAD (being happy at the time of finding the bike the price), I did not realize how bad the rust was on the fork nor the chopped teeth on the drive train. The middle chainring has 4-5 missing tooth although when I ride it, the chain does not slip. The first chainring has a teeth missing as well. How salvageable is the frame from the rust considering that there is a little piece missing on the fork (left side of the fork as shown in the last photo). I imagine it is better to replace the entire crankset instead of just the middle one. I do feel like I got scammed because I didn't realize that the crankset was in such terrible condition and missing teeth meanwhile the ad photos were never close-ups and low quality overall but it is my fault for not checking everything. I looked at the frame for cracks and rust and it did not look as bad! Even the front derralieur is crumbling a bit where the bolt/screw goes. What are your suggestions, the bike does ride nicely. Can OA bath save this, or other alternatives (apart from buying a new fork).



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there appears to be a little chip near/or the fork

The rust on the inner face of that fork leg is what I would be most concerned about as it looks to have worked in deep into the steel on the fork leg.
Don't hesitate to start taking off the finish in that area to find out how bad it is, as it could be a major riding safety concern.
of it is really bad, you might be looking at having a builder replace the fork leg or if there's just too much rust damge, replacing the whole fork.

What is the simplest way to taking off the finish?

I'd start with a flat screwdriver to get down to the meat. If that is too scary, use a stainless steel wire brush from Ace. Then before you touch it up, sand it til its shiny--probably plenty of metal there. My people tell me that production bikes are overbuilt and therefore I don't worry and only try to make it look "nice enough" But if it is really deep, it bugs me.

AND ummm, is there a picture of the whole bike? Drive side please.

Thanks for the tip, I tried flat screwdriver and it didn't get anywhere but the stainless steel wire brush worked. It seemed like the paint was chipping off as you can see still see that area. I only attempted to brush one side since it was the worse one looking. Let me know what you see, also I uploaded the picture of whole bike, also I know I shouldn't be putting the bike upside down but I wanted to take a picture of the head tube


https://cimg4.ibsrv.net/gimg/bikefor...20464380cd.jpg
https://cimg8.ibsrv.net/gimg/bikefor...c509ca28aa.jpg
same side as ^ but another perspective
https://cimg4.ibsrv.net/gimg/bikefor...1422348324.jpg
2nd leg of the fork, which looks fine to me
https://cimg9.ibsrv.net/gimg/bikefor...305df597f1.jpg
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“Missing teeth” on chainwheels usually aren’t missing. That’s a design feature, although a fairly early one. The flattened teeth are meant to aid in shifting by releasing the chain easier on shifts.

Thank you this is the same crankset https://www.ebay.com/itm/284517359013 and it has the "missing teeth" indeed. I do wonder why someone changed the crankset from biopace to this.

Personal preference. Lots of people, myself included, didn’t like Biopace.

Yea you paid to much. Depending on the time you have and your inclination, I'd suggest completely disassembling the bike and cleaning up all the components and do your research on on each part. Then you can look them up on eBay and do the math that might offset your "loss". The frame can be stripped, soaked and sanded to to determine weather its safe enough to ride. If yes , get it powder coated for $100. If not take that $100 and shop for a frame, as you already have a start on components.

Unfortunately all of the parts are not original (except drop bar and brake levers but I am not 100% sure on these). It appears to me that it was simply rust but got through most of the paint (on the forks). I should apply the frame rust saver and apply something else to keep the frame safe without needing to strip all the frame for time being.

I don’t want to be an alarmist but I would be VERY concerned about rotted forks and would inspect them, and the rest of the frame, very closely before putting them into use.

Not that you really asked but I would be too concerned about metal integrity to put that machine into use even though my moniker is “Rusty”.

Well there's the "Always looking for a bargain for a Centurion Pro Tour, Fuji Touring series V, Lotus Odyssey, Miyata 1000, 615, 610 and Specialized Expedition.Trek Touring bikes like 720, 620, 520" plan......If you've got storage space for the all the 'bargains"

https://cimg6.ibsrv.net/gimg/bikefor...b078e1c987.jpg

Do you think a bike shop can check the integrity of the bike without the need to strip the paint?

lol yes well haven't found any bargains yet. It appears that you have a big storage space!

It probably depends on the shop. A lot of liability if they say it’s okay and it fails.

I wouldn’t be surprised if many shops would rather sell you a bike.

I will attempt to keep using the stainless steel wire brush on the entire fork, how can I tell if the integrity is gone. Shouldn't the rust make the metal super soft and be able to make a hole or can you give examples?

Your going to have to make a judgement call. I would be poking and scratching around the pits with ice pick to try and find any thin spots. Having it sand blasted by someone with a "light touch" would strip the rust from what's left.

Take some sand paper to the rusty parts. You may not have to work long before you get to shiny metal with only a few specs of rust. Take a picture and show us. Then use some rust converter over all (including inside the steerer).
Then put the steerer in a vise and start yanking on the blades every which way. Then put the fork back in the frame, attach a wheel and start banging the front end around--see what happens. I predict that it is rideable.

I sanded by hand for an hour or so but using 220 sandpaper really helped towards the end. You can see that there are black spots but I hear that is called "black oxide". Is this enough of sanding or more?
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Interesting that the rest of the frame looks good. Growing up in St. Lawrence Cty. N.Y. with salted winter roads, maybe Montreal is the same and the salt collected on the fork crown? Hopefully a frame builder type Miyata Cogniscenti can shed some light on that fork assembly. Looks pretty heavy duty and if the component layers aren’t separating…

Yep we have same roads if not possibly more snow (more salt). Apart from the rust on bottom of the frame as seen in my first photo, the frame is still nice. The fork is still solid and it just has that gunk at the bottom but I am not sure if that is mix of salt/paint or just how it was made in the factory because it is hidden.

The OP paid about $160 USD for this bike -- if the rest of the frame is ok and components are generally solid I'd say he's ok -- the fork photos do not look too bad to me. Was it a screaming Deal? No. Did he overpay? Judgement call. He's got that much or more in components (photos dark so hard to say what shape they're in, but assuming decent), and is getting to tinker and learn. If he overpaid it's not by much -- not a big deal in the overall scheme of things. OP, I think you're ok -- fix and ride! :)

Yep. My LBS tried to tell me that a broken Campy rear axle I brought in looking for a replacement was a sign the whole bike was unsafe. :(

I came back when the crusty old dude was in the shop -- he sold me a new axle without the absurdly supercilious attitude of the typical LBS young racer guys who know nothing about anything made prior to 2018 and do not care to learn. Hummph. Now get off of my lawn! :)

So do you guys paint/spray rust converter and paint the area?

I would hit it with a Rust Remover. Navel Jelly works. Evaporust works. Rustoleum has products. Then prime it with a rusty metal primer. I've had good luck with Rustoleum Spray can stuff, spray it into a dixie cup and brush on with an acid brush. You should be able to cover that up with model paint or nail polish to get a match.

If I use a rust reformer instead can I just go with any spray paint or does it have to be specifically for rust paint

That fork looks much better than initial impressions. Nice work cleaning it up.

I am not a fan of rust converter since it will turn any rusty surface black/brown permanently. If you can paint over it it wouldn’t be too bad but I have a bike that the PO slathered the chrome with rust converter and I think it looks horrible.

Naval Jelly, Evaporust et al, clean, prime and paint. That’s my normal rejuvenation, FWIW.

Rust reformer is sometimes billed as a primer. I'm not an expert but I've read some of the cans. It seems to me that the reformers claim to fame is to seal up existing rust so you can paint over it. I'm of the opinion that getting rid of rust is better than covering it up.