7-speed downtube to 7-speed STI

Discussion in 'Cycling Equipment' started by cyclist_nc, Jan 26, 2004.

  1. cyclist_nc

    cyclist_nc New Member

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    I have an older 80's road bike with 7-speed suntour GPX components. I would like to change the down tube shifters to 7-speed STI. It is my bad weather bike and I don't want to spend much money upgrading. What are my options?
     
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  2. Kaboom

    Kaboom New Member

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    there is a very meagre chance of it working if u are able to grab a pair of 7-speed stx shifters...
    in those older systems i dont think that the spacing would be much trouble. And if it is and if u are willing to spend a LONG time with this you can make ur own custom spacers to make it work. Theoretically with the correct spacing any 7-speed shifter should work.
     
  3. cyclist_nc

    cyclist_nc New Member

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    I have been able to interchange the suntour cassette with a shimano cassette without any problems so I wouldn't think the spacing is an issue. I guess the question is whether shimano 7 speed STI will work with GPX deraillers.
     
  4. froque

    froque New Member

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    You can get shimano Sora 7 STI, and to fix the shifting problems you will have with you current freewheel, you could find a shimano SIS 7 speeds freewheel and of course a new chain, if you search hard you can get all that for not much money.

    Make sure the freewheel is similar (in tooth count) or almost similar to that one you have (To avoid problems, because the capacity of your derraileur is not known to me) .

    For example if yours is 14-23 do not buy 14-29 or something like that.

    Other option to consider is to go all the way to 9 speeds, but that is more expensive and your frame will need to be re-spaced to hold 130 mm hubs.

    br

    froque
     
  5. daveornee

    daveornee New Member

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    I agree with the above.
    Other options are Campy 8 shifters and Campy 8 Cassettes as well as Sachs 7-speed & 1997 8-speed are all 5 mm spacing.
     
  6. boudreaux

    boudreaux New Member

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    Pretty sure the GPX is an index system. Start with 7 speed sora shifters or RSX 7 speed if you can find them.The deralier may not be Shimano compatible, so that would need changed if no workee.The cassete or freewheel may or may not be compatible. Suntour barend shifters are alot cheaper and almost effective if you can find them: try ebay. Shimano 7 speed barends might also work.
     
  7. Gonzo Bob

    Gonzo Bob New Member

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    The cable travel requirements are different between Shimano and Suntour derailers so mixing won't work. I have GPX stuff on one of my bikes and bunged up the rear derailer a while back. I tried a spare Shimano 600 I had laying around but could not get it to index well with the GPX levers. So I picked up a used Suntour Edge on eBay which works great. I would expect that Suntour derailers with Shimano levers will also not index well.
     
  8. boudreaux

    boudreaux New Member

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    I've had mixed results with suntour/shimano 7 speed index stuff. Suntour index barends would not work with a shimano index mtb RD,but Suntour thumbshifters work fine with an otherwise shimano 7 speed drivetrain. Go figure...
     
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