Narhay

400 miles in northern Ontario just around the block.

The Golden Boy 

Congratulations! Lovely Bike!!!

dailycommute

The derailleur does look a bit off, but when I picked up my 85 T700 the superplate was mounted similarly, I just adjusted it level and rode it hundreds of miles. Then got a bit paranoid as believe it was nesteel said he had one explode in the middle of a long ride. I replaced it with a deore dx long but the superplate still looks and seems to function well now in the keeper part bin, it seemed intended for the the t700 34t rear cog x granny front ring as it shifted to that seamlessly vs other long cages that will bind and pull inwards if not careful. I would not recommend taking the plate apart but you can dribble lube into and clean it somewhat to where it spins smooth and use a pipe cleaner at the edge as you spin it to capture grit. I think when sand gets in there it can quickly wear it out, but so long as you are willing to remove it regularly and lube it should be okay. I found lubing it removed with plate gap facing up and soak a bit seemed to work better than on the bike.

SergueiGatorski

Beautiful bike with the tan sidewalls !

ryansu

funny I always get pulled in by the grail shaped lantern nice find OP

LBCwanabe 

The derailleur seems to be working as
should. It’s a beast

gerard2013

Beautiful, it looks just like mine did in '84, got it from BJ's bike shop in Mpls for $500. I started having trouble with the derailleur after about 25 years but it worked great till then.

uprightbent

My favorites of all time, my 89' 1000, picked from a garage wall nearly unridden, fully torn down and rebuilt as a regular rider. The original black rack is back on with vintage NOS blue Cannondale panniers.
The 610 (with a Grand Touring decal) is an 84' I picked up for only $100, with that infamous Mountech rd cracked and into the spokes with a bent hanger. With a lot of work, this is what it looks like now.
Kept both mostly original, with wheels, drivetrain, etc. They are a joy to pedal.

LBCwanabe 

Is the stem on that 89 stock?

uprightbent

No, it's not. The original was black, and stamped with the Miyata M logo, which I foolishly sold off amongst other parts. Wanting everything to be matching and bright polished silver, I usually go with Nitto, even though I don't really like the look of a short 70mm stem, but my back needs its. Seatpost also not original, first owner tossed it with the original saddle, when he opted for some awful cruiser saddle.

nomadmax 

Good for you! Let's hear the story on how that one got to be "the one".

BikeWonder

What are the Miyata stamped stems worth? I have one laying around in hopes of attaching it to a potential Team Miyata I may come across one day.

uprightbent

Good question, I don't think they're too valuable. Can't recall what I got for mine, since it was grouped with some other parts, maybe $20-40 is likely, depending upon scratches. Certainly much more if someone's competing a project and needs exactly what you have.

Kuromori

I have a super-plate that I'm too lazy to check at the moment, but if I remember correctly, it's basically a duopar except with patent dodging and the tension spring tidily tucked away inside the A-knucle. It's actually quite clever and involves little pullies and a small cable which allows the parallel action to have a greater range of motion than the duopar's parallelogram, letting it transmit the spring tension from the A-knucle to the cage as well. The B-pivot spring doesn't seem to do much of anything. Mine at least, even stripped, cleaned and freshly greased,simply does not want to move at the B-pivot unless there's a huge amount of chain being taken up, although mine could just be binding. All the action is at the A-pivot to cage linkage, which is driven by a single cage tension spring like a duopar. There is tension adjustment, but it just increases chain tension rather than working against another spring. The self-adjusting action relies on the cage rotating clockwise as much as possible. Static friction is kind of high, and it won't self adjust if you knock it out of position, but seems to correct after a shift. It does contain some plastic internal parts I think, so I would avoid especially harsh chemicals. A good spray of WD-40 followed by some oil like restoring gummed up STIs should work okay.

People always say trimec/mountechs are like duopars/superplates, and I'm too cheap to purchase one simply to disassemble, they just look like a more convoluted dual-sprung set up with balance springs, except the derailer doesn't float between the B-pivot and the A-pivot like most Shimano derailleurs made in the past 30 years. Instead the upper spring is located at the A-pivot which is no longer the cage pivot, and it balances against the new cage pivot spring which is on the extra arm.

In regards to self destruction, it's the plastic ring on the guide pulley that tends to disintegrate. Later models replace it with steel, but ultimately, the guide pulley is a non standard part and not replaceable when it does wear out.