7 to 9 speed?
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Thread: 7 to 9 speed?

  1. #1
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    7 to 9 speed?

    if i recall... it is possible to use a 9 speed cassete... minus one of the cogs and put this on a 7 speed hub??essentially ending up with 8 rear gears (that have the spacing of 9speed).. im asking because it just isnt worth it to upgrade the whole wheel and drivetrain on my bike.. but can get a great deal on a set of 9speed shifter/brake levers so i can shift without taking my hands of teh bar... which is kinda risky around here the way some people drive their cars
    Ash to ash, dust to dust
    Another bike bites the dust

  2. #2
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    The shifters are really the biggest expense in upgrading from 7 to 9. In addition to the shifters all you need is a new hub or hub shell, 9-speed cassette and chain. This will all depend on the rear dropout spacing. Some 7-speeds are 126mm, some are 130mm. If yours is 126mm the frame could be spread, but only if steel. If you have 126mm spacing on an aluminum rear triangle then you are probably right in saying that it isn't worth it.

    ~Al

  3. #3
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    Quote Originally Posted by Al1943
    The shifters are really the biggest expense in upgrading from 7 to 9. In addition to the shifters all you need is a new hub or hub shell, 9-speed cassette and chain. This will all depend on the rear dropout spacing. Some 7-speeds are 126mm, some are 130mm. If yours is 126mm the frame could be spread, but only if steel. If you have 126mm spacing on an aluminum rear triangle then you are probably right in saying that it isn't worth it.

    ~Al
    i know the most expensive part is the shifters thats why im intereste since i can get such a reat eal on one that the shop has laying around... my frame is steel and it does have 126mm spacing.. but i just CAN'T justify the expense of a new hub and haveing a wheel laced.. the bike just isnt worth that much attention.. if i can get away with using a 9speed cogset but omit say the 12 tooth sprocket.. or the 13 whichever i can.. ill be in business!
    Ash to ash, dust to dust
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  4. #4
    LC
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    Quote Originally Posted by _Marty_
    i know the most expensive part is the shifters thats why im intereste since i can get such a reat eal on one that the shop has laying around... my frame is steel and it does have 126mm spacing.. but i just CAN'T justify the expense of a new hub and haveing a wheel laced.. the bike just isnt worth that much attention.. if i can get away with using a 9speed cogset but omit say the 12 tooth sprocket.. or the 13 whichever i can.. ill be in business!
    Yes 8 of the 9 speed cogs fit quite nicely on a 7 speed cassette hub.

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    Safety?

    If you feel that taking your hands off the bars to shift is risky, then maybe you should be focusing on bike handling skills rather than component upgrades. This is not meant to be a dig, but shifting should not be either distracting or destabilizing for a rider, any more than taking a drink from a water bottle. What you propose will likely involve a LOT of tinkering on your part to try to get things to work right, which they may never do. If you think that a balky shifting system will somehow be "safer" than downtube shifters, you will not likely be satisfied. If your rationale for doing this is actually something other than safety, and you like to tinker with the stuff, then go ahead and have fun.

  6. #6
    century rider
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    You need a 9spd rear derailleur..

    I've done this on a mtb 7spd hub. Got nine speed cassette, took out one cog and it fits the 7spd hub, making it 8spd. But if you are using 8spd shifters, there will be a skip on one of the cogs coz an 8spd shifter will still need to move thru an 8spd hub though there's 8 cogs on your 7spd hub. Using the 9spd RD, on an 8spd shifter would solve this as the RD would move 8cogs within 9spd spacing on an 7spd hub. This is because the throw of the 9RD is shorter than an 8RD, meaning it can cover 8cogs on a space allotted for 7spds.

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    If you can't afford to make a true 9-speed out of it then I suggest that you wait until you can or just save your money for a new bike. I don't see how cobbling something together just to make it STI makes any sense.

    ~Al

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    Quote Originally Posted by battaglin
    I've done this on a mtb 7spd hub. Got nine speed cassette, took out one cog and it fits the 7spd hub, making it 8spd. But if you are using 8spd shifters, there will be a skip on one of the cogs coz an 8spd shifter will still need to move thru an 8spd hub though there's 8 cogs on your 7spd hub. Using the 9spd RD, on an 8spd shifter would solve this as the RD would move 8cogs within 9spd spacing on an 7spd hub. This is because the throw of the 9RD is shorter than an 8RD, meaning it can cover 8cogs on a space allotted for 7spds.
    Not quite right. All index-compatible Shimano rear derailleurs, road and mountain, 6 through 10 speed, with the exception of 6 through 8 speed D/A, use the same actuation ratio. First generation (6 speed) D/A used a different ratio, the levers pulled less cable per click. Shimano stuck with that through 8 speed, but when D/A 9 was introduced, they changed the derailluer to be the same as the rest of the line.

    I've never seen any rear derailleur without sufficient travel to swing over an 8 speed cassette, and if they'll do 8, they'll do 10.

    As long as the cassette matches the shifter, it'll index. The newer derailleurs may shift better than the older ones, but that's true regardless of the number of speeds. A 1986 600EX derailleur will index a 10 speed Shimano cassette, using 10 speed levers. It won't shift as quickly and quietly as the new D/A, but then, the new D/A will shift 6 speeds better than the old 600, too.

    "Speededness" doesn't exist in Shimano derailleurs, except for the folks in the marketing departments.

    And "8 of 9 on 7" works great, as long as you have a Hyperglide freehub body. It won't work on Uniglides.

    --Shannon

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