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Old 06-29-07, 09:51 PM   #1
karmantra
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Miyata 618 GT--What year?

Dropped by a sports gear consignment store & spotted a blue Miyata 618 GT bicycle, 54cm frame, 700 wheels, 'radial' tires, Suntour handlebar end click shifters, looked like it was original equipment.
Curious to know what years the 618 GTs were available, ('87 on to?) & if they were considered a fine touring level bike in the same way as the Miyata 610 & 1000. Any info would be appreciated.
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Old 06-30-07, 05:55 AM   #2
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What you saw is a 1989 model. The 618GT was a mid-range, grand touring model. It does not have the stature of a model 1000 but is still a good bicycle and basically an evolved model 610. The frame uses Miyata's excellent Spline Triple Butted tubing but used a Mangalight fork to reduce costs over the 1000's splined CrMo fork.The frame also has lacks the 1000's bosses for low-rider racks and doesn't not have the boss for mounting compressed air bottles as on the 1000.

Components are SunTour's XCM3040 paired Dia-Compe 983 cantilevers and Sanshin hubs, versus the 1000's Shimano Deore II group. One could argue over the relative merits of the groups, but most people considered Deore to be the better group, and it was generally found on more expensive bicycles than was XCM. The one disandvantage with SunTour is that it can sometimes be difficult to find compatible replacements if one of your AccuShift components ( freewheel, rear derailleur, shift levers) has broken or worn out. The one component advantage of the 618GT over the 1000 are the bar end shifters, which allow you to keep your hands on the abrs while shifting. This can be a very desirable feature when your handling a fully loaded touring bicycle.
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Old 06-30-07, 09:33 AM   #3
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Thanks T-Mar for the detailed response on the 618GT--the shop wanted $125 for the bike and it is in fine original condition, but it did have some quirks in the drivetrain--sticky freewheel, notchy shifting--is that an indication that the Suntour Accushift system may need some work/replacing? Thanks again T-Mar!
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Old 06-30-07, 09:49 AM   #4
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Quote:
Originally Posted by karmantra
Thanks T-Mar for the detailed response on the 618GT--the shop wanted $125 for the bike and it is in fine original condition, but it did have some quirks in the drivetrain--sticky freewheel, notchy shifting--is that an indication that the Suntour Accushift system may need some work/replacing? Thanks again T-Mar!
The shifting is supposed to be notchy, at least for the rear derailleur. It's called indexed shifting. The lever should click into position, eliminating the need to fine tune lever position. Most AccuShift levers have a setting that can be switched between indexed and friction (traditional, infinitely variable) shifting modes, but I'm not sure about the bar end shifters. Anybody else know?

Sounds like the freewheel mechanism is gummed up. Usually this is easy to fix. Remove the freewheel, lay it down and drip some solvent into the gap between the inner and outer freewheel body. Spin the freeweel and repeat several times, until it spins freely. This should flush out the dirt. Repeat the process using oil to lubricate the freewheel.
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Old 07-01-07, 12:55 PM   #5
karmantra
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Quote:
Originally Posted by T-Mar
The shifting is supposed to be notchy, at least for the rear derailleur. It's called indexed shifting. The lever should click into position, eliminating the need to fine tune lever position. Most AccuShift levers have a setting that can be switched between indexed and friction (traditional, infinitely variable) shifting modes, but I'm not sure about the bar end shifters. Anybody else know?

Sounds like the freewheel mechanism is gummed up. Usually this is easy to fix. Remove the freewheel, lay it down and drip some solvent into the gap between the inner and outer freewheel body. Spin the freeweel and repeat several times, until it spins freely. This should flush out the dirt. Repeat the process using oil to lubricate the freewheel.
I should have said indexed shifting, not 'notchy'--apparently only needs some adjustment on the shifters, and the freewheel suggestion you made is probably all it needs--the bike otherwise is in excellent & original condition, only some scratches on the fork. It is a 54cm, rides a bit high on the top tube for short-legged me (usally a 50-52cm is best), but the top tube length is perfect, and it rides well--does $125 seem reasonable? Thanks!
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