Can I use a 9 speed chain on a 7 speed 1991 Suntour "trekking" crankset?
09-13-11, 08:02 AM
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Can I use a 9 speed chain on a 7 speed 1991 Suntour "trekking" crankset?
I may want to upgrade to a 3x9 drivetrain but would like to avoid buying a new crank.
09-13-11, 08:06 AM
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The size of the cranks is not the determining factor for a chain. The size of the cassette is. 6,7,8 speed cassette will work with an 8 speed chain due to the spacing of the gears. For a 9 or 10 speed you need to match the chain to the cassette. 9 speed chain with a 9 speed cassette, etc.
09-13-11, 08:06 AM
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Yes, There shouldn't be a problem running a 9s chain on a 7s crankset.
I can't give you an absolute all clear, because some cranksets may have enough chainring separation for the chain to hang on the tips of the inner ring teeth while leaning on the face of their larger neighbors. In extreme cases the gap is wide enough for the chain to wedge into the gap.
You can test for this without installing the chain simply by gauging your 9s chain against the gaps between the chainrings. If you can push it behind the teeth it's definitely a no go. If it doesn't fit behind but seems like it'll ride the tops, you can use it, but will have to keep the tension off during down shifts.
I can't give you an absolute all clear, because some cranksets may have enough chainring separation for the chain to hang on the tips of the inner ring teeth while leaning on the face of their larger neighbors. In extreme cases the gap is wide enough for the chain to wedge into the gap.
You can test for this without installing the chain simply by gauging your 9s chain against the gaps between the chainrings. If you can push it behind the teeth it's definitely a no go. If it doesn't fit behind but seems like it'll ride the tops, you can use it, but will have to keep the tension off during down shifts.
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Last edited by FBinNY; 09-13-11 at 08:28 AM.
09-13-11, 08:07 AM
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According to Sheldon Brown, you can. But he also says it's not ideal.
https://sheldonbrown.com/speeds.html
https://sheldonbrown.com/speeds.html
09-13-11, 12:50 PM
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09-13-11, 03:48 PM
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How about the reverse? I've got a 10 speed Ultegra crankset laying around and a high schooler at our church needs a new crankset. Current set up is 5 speed freewheel. Will this work with 5 speed chain? Other thought was to swap out the freewheel for a 6 speed (the freewheel is getting near needing replacement anyway) and go with a 6/7/8 speed chain (chain, also, could use replacement). What has worked/not worked for others?
09-13-11, 03:52 PM
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I did a 9-speed upgrade on a friends 7-speed, used the old 7-speed RSX triple crank and derailleurs, new 9-speed hub, shifters, cassette, and chain. It worked perfectly, better than expected.
09-14-11, 08:20 AM
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I had problems with the 9 sp chain getting stuck in the gap between the rings on front downshifts after I upgraded my 3x7 MTB to a 3x9. Sheldon Brown points out that this can happen. It only happened when shifting from larger to smaller front rings when the chain was on the right side of the cassette. I got frustrated having to think too much about chain position so I just changed to 1x9. Your results may vary.
09-14-11, 08:48 AM
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If you have been using the crank for 20 years, you might need new chainrings,
the replacements can be purchased with a thinner tooth profile , still 1/2 pitch.
that is the significant difference for 9 speed chains.
8 speed stuff is still plentiful , the chains are a bit internally wider,
do the math and see what that extra ratio gets you , might not be meaningful.
I put in Thousands of loaded touring miles on 6 by 3 drivetrains ,
across Europe and Eire/scot-land..
It's the Ratios , and the range spread, not the number of gears, IMHO.
the replacements can be purchased with a thinner tooth profile , still 1/2 pitch.
that is the significant difference for 9 speed chains.
8 speed stuff is still plentiful , the chains are a bit internally wider,
do the math and see what that extra ratio gets you , might not be meaningful.
I put in Thousands of loaded touring miles on 6 by 3 drivetrains ,
across Europe and Eire/scot-land..
It's the Ratios , and the range spread, not the number of gears, IMHO.
Last edited by fietsbob; 09-14-11 at 08:52 AM.
