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-   -   Miyata 600GT (https://www.bikeforums.net/classic-vintage/1207371-miyata-600gt.html)

Dayz23 07-13-20 11:19 AM

Miyata 600GT
 
Hey! Picked up a 600 GT. 275 CAD.

Before:

https://cimg4.ibsrv.net/gimg/bikefor...1c40313fc.jpeg
https://cimg6.ibsrv.net/gimg/bikefor...79e72bb5e.jpeg

After: (trued wheels, cleaned each part scrubbed rust etc. Replaced foam bars with new bar tape)


https://cimg6.ibsrv.net/gimg/bikefor...0974fe134.jpeg
https://cimg8.ibsrv.net/gimg/bikefor...c31f85d13.jpeg
https://cimg2.ibsrv.net/gimg/bikefor...79d87089a.jpeg
https://cimg8.ibsrv.net/gimg/bikefor...c8a61935e.jpeg
https://cimg9.ibsrv.net/gimg/bikefor...0d04e1a1c.jpeg

Rear rack porn

https://cimg2.ibsrv.net/gimg/bikefor...9d2ec25e0.jpeg


I want to replace the derailleur and free wheel cassette . Not sure if it will lose that authentic feel and look.

Piff 07-13-20 11:33 AM

Nice job, and nice bike!

But, is there any reason to replace those parts?They look brand new. It's a lot of money for a new rear hub, derailleur, and shifters when what you have already works. Is the shifting sloppy with your current stuff?

Dayz23 07-13-20 12:09 PM

Yes itís real sloppy. Of course I havenít tried adjusting the hanger the screws or anything So that will be my first step. But the issue is the chain is super worn and I feel like it did damage to the chain rings. I realized it when I was cleaning it, and then even more so when I ride as the chain goes directly over the cogs and doesnít slip in. So I ordered a kmz chain from amazon and will put that on. Iím hoping that + adjusting the tensions will get me shifting smoothly.

i gotta say the bar cons are super scary when riding fast. U canít leverage ur hand on the bar while shifting, u kinda have to grab just the tab, pretty precise, also moving my hand of the bar to shift is not that easy. Iíll get used to it.

Dfrost 07-13-20 12:43 PM

Welcome to C&V, home to many Miyata lovers. That 600GT cleaned up nicely! A lovely bike that now looks like new. What year is it? A quick perusal of several Miyata catalogs didnít reveal that model number and color, but maybe the Canadian versions were different?

https://www.ragandbone.ca/Miyata/miyata_selector.html

Give it a few more rides with the bar-end shifters. Many folks love them. If you decide to use something else, folks here will be happy to buy them and help you with a conversion.

If the rings and cogs are worn as you say, expect that the new chain will be even worse on them. But you might not need to replace all the rings, and individual 110/74 rings are readily available. Where are you located? Lots of us include that in our User CP data, which appears on the left, so we can help find useful resources like bike co-ops.

Replacing the freewheel or cassette - they are not the same, not sure which this bike has - will have no effect on feel or looks. They are considered consumables. Being friction-shifted, the brand or even speed count won't matter, assuming it fits on the hub and between the dropouts.

Doubt that a derailleur that looks that fresh is worn out. Not even a scuff mark! The derailleur hanger looks pretty straight in your last photo. Check for free play in the pivots, and be sure the mounting bolt is tight.

Dayz23 07-13-20 02:22 PM

Hey, thanks for the warm welcome. Iím in Toronto Canada. Thanks for the correction on freewheel/ cassette distinction. I went and took a look at the derailleur seems like maybe the limiter is off as it doesnít take all the way to smallest cog.

The Golden Boy 07-13-20 03:37 PM

That looks strikingly similar to the 1990 Miyata 1000 LT.

https://live.staticflickr.com/65535/...3e7e10a6_o.jpgM1000LT Drivetrain by Dave The Golden Boy, on Flickr


Although the colors don't match- but this is (I think) the 1990 catalog specs:

https://live.staticflickr.com/4750/2...170b390e_o.jpgMiyata 1990 Specs by Dave The Golden Boy, on Flickr


You might have some issues with replacing the derailleur and freewheel. This system is Accushift- the other main indexing system of the 80s and early 90s. It's really only compatible within itself- or specific combinations of stuff. Accushift used different spacing than Shimano's SIS (in 7 and 8 speed); additionally, the derailleurs used a different pull ratio. To get best results with 7 speed Accushift- you should use an Accushift freewheel, derailleur and shifter. That XCE stuff is pretty styley- I'd see how the new chain does you. I'd also echo the advice of giving the bar end shifters a chance- there's millions of people who prefer bar end shifting.

You've got a beautiful bike! Congratulations!!!

Dayz23 07-13-20 08:43 PM

Hey thanks for the info, that 1000 looks beautiful.

So if I did want to replace components that are part of accushift what can I choose from ?

Piff 07-13-20 09:30 PM

7 speed Accushift is a bit of a dead end because it only sometimes seems to work with parts from other brands. 7 speed accushift also can be expensive to source. If you do start to replace components, ditch accushift wholesale. You already have a nice suntour indexed drivetrain, I see no reason to spend more money on suntour stuff. Go to shimano 9 or 10 speed for a new drivetrain if you want to upgrade your stuff.

For the moment I would focus on getting your shifting working. Depending on how the bike has been stored, that could mean replacing cables/housing because of rust. Personally, when I buy a decades old bike off craigslist and it seems to be all original, I always give it new cables/housing. If the shifting is still crappy, perhaps do some sleuthing to see if it's because of a single component. But your stuff looks pretty new. I bet it'll be fine given a full overhaul and tuneup. Oh yeah, and that new chain.

The Golden Boy 07-13-20 09:48 PM


Originally Posted by Dayz23 (Post 21586059)
Hey thanks for the info, that 1000 looks beautiful.

So if I did want to replace components that are part of accushift what can I choose from ?

Thank you!

Do you mean what specific components?

IMO/IME and all that... if you're not dorky into the whole Suntour component hierarchy- Stay with XCE- it's good stuff. The performance will not improve noticeably, the weight *may* come down a bit, and you might think the upper level parts are prettier.

I'm all dorky about old Suntour stuff- so to me, I kind of dig the prestige (if just for myself) of having the top of the line stuff- XC Pro was the flagship component group. XC Comp was under that.

My personal opinion- it's not worth it to go through the expense and effort of hunting down parts that would be clean enough for your bike for little to no improvement for something you don't particularly care about while you have a set of REALLY clean examples of a good group.

I would strongly suggest you ride it for a while- it's a cool group, in really nice shape, and IMO- Accushift works well when it's working as a unit without trying to fit SIS parts into it.

When I got my M1000LT- some of the parts were scuffed/missing so I was going to upgrade it to M735 XT, I accidentally found an XTR M900 FD... so I did the derailleurs and seat post in XTR, an XT crank and kept the Deore brakes and 600 bar end shifters.


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