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  1. #1
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    How do you change a 21-speed into a 10-speed?

    Hello,
    I have a Trek 7500 that I want to change from a 21-speed to a 10-speed.
    Do I just have to take off the gears and buy new ones, or is it just an ajustment that I have to make?
    Help!
    Thanks,
    Leah

  2. #2
    Prefers Aluminum Sprocket Man's Avatar
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    Why would you want to make your bike even less versatile than it already is?

  3. #3
    AEO
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    Senior Member AEO's Avatar
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    oh, boy, where to begin...

    new wheel, new cassette, new shifters, new chain
    Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
    http://sanfrancisco.ibtimes.com/arti...ger-photos.htm

  4. #4
    ..... Jynx's Avatar
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    do you mean you currently have a triple in the front and seven speeds in the back meaning 21 speeds?

    When people here refer to a 10 speed they mean 10 in the back and either 2 or three in the front (20 or 30 speeds)

  5. #5
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    I dunno... Let me know, because I was thinking of switching out the 6 speed in my BMW M3 over to a nice 3 speed.

  6. #6
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    Well Leah your going to get lots of good advice but my thought is have you really thought this through//when you have read and studied the various options you may have a different idea /Ithink I might do 3 on the front derailier and 3 on the rear so I had a 9 speed/Kenneth

  7. #7
    Senior Member
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    This is a hybrid, no? I'd just leave it be. 7 speed parts are fairly cheap, so if you need to buy spares, it will be more economical to replace the 7 speed parts when they wear out.

  8. #8
    Infamous Member chipcom's Avatar
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    Moved this to Bicycle Mechanics - but my advice: leave it alone.
    "Let us hope our weapons are never needed --but do not forget what the common people knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny. If guns are outlawed, only the government will have guns. Only the police, the secret police, the military, the hired servants of our rulers. Only the government -- and a few outlaws. I intend to be among the outlaws" - Edward Abbey

  9. #9
    Senior Member Fissile's Avatar
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    I guess Leah wants that "10 speed" to go along with her disco ball, lava lamp and bell bottoms.

    Leah, back in the day, bikes were called "10 speeds" because they had five gears in the back and a double chain ring up from, 2X5 hence "10 speed". Today a bike's speeds are a reference to a how many gears are in the back. 7 cogs(gears) = 7 speed, 8 cogs = 8 speed, etc. The crank gears are called "chain rings". If you have 2 chain rings, you have a "double", 3 chain rings and you have a triple. So, if you have 7 gears in the back, and 3 chain rings up front, you've got a 7 speed triple, not a "21 speed". Why you would want to change this back to a 1975 configuration, I haven't a clue. If you really insist, I'd think you'd be better off trading your current ride instead of ripping out gears. Tell you what, give me your 7500 and $100 cash, and I'll give you a spiffy lime green Schwinn Continental "10 speed". I'll even throw in a shiny chrome spoke protector. What a deal!
    Critical Mass

  10. #10
    Senior Member oldbobcat's Avatar
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    I think Leah gave up on us and took her 21-speed home.

  11. #11
    Pwnerer Wordbiker's Avatar
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    Quote Originally Posted by Leah View Post
    Hello,
    I have a Trek 7500 that I want to change from a 21-speed to a 10-speed.
    Do I just have to take off the gears and buy new ones, or is it just an ajustment that I have to make?
    Help!
    Thanks,
    Leah
    Remove 11 gears.
    Quote Originally Posted by ahsposo View Post
    Ski, bike and wish I was gay.

  12. #12
    aka Tom Reingold noglider's Avatar
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    I want to be kind to newcomers, but sometimes the questions are so strange that it crosses my mind that some are trolls. I'm not saying Leah is. She might be misguided by her local experts. And she may not be a regular, which would explain the apparent hit-and-run posting. But who can say?

    Leah, if you're out there, please explain further. We'd like to help!
    You don't read my signature anyway, do you?

    Tom Reingold, noglider@pobox.com
    Residences: West Village, New York City and High Falls, NY
    Blogs: The Experienced Cyclist; noglider's ride blog

  13. #13
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    Quote Originally Posted by noglider View Post
    I want to be kind to newcomers, but sometimes the questions are so strange that it crosses my mind that some are trolls. I'm not saying Leah is. She might be misguided by her local experts. And she may not be a regular, which would explain the apparent hit-and-run posting. But who can say?

    Leah, if you're out there, please explain further. We'd like to help!
    What's the point of a troll, anyway? I thought they just exist to pi$$ people off of competing things... Chevy guys posting of all the crap that Dodge has on a Dodge forum, for example... They can also just post absurdly stupid questions?
    Wow... I wonder if I've been called a troll...

  14. #14
    aka Tom Reingold noglider's Avatar
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    If you have to ask, you'll never understand the appeal of trolling.
    You don't read my signature anyway, do you?

    Tom Reingold, noglider@pobox.com
    Residences: West Village, New York City and High Falls, NY
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  15. #15
    Upstanding member. Mike T.'s Avatar
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    Y'all missed the easy answer to the possible troll - two minutes work twiddling derailer limit screws will create a "10 speed" at zero cost. Job done.

  16. #16
    aka Tom Reingold noglider's Avatar
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    No, we saw that, but sometimes, understanding the question and what's behind it is more useful than answering the question.
    You don't read my signature anyway, do you?

    Tom Reingold, noglider@pobox.com
    Residences: West Village, New York City and High Falls, NY
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  17. #17
    Great State of Varmint Panthers007's Avatar
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    Probably hanged herself from a rafter in the garage. Good job. You've killed.
    How do you keep an idiot in suspense?

  18. #18
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    Okay, I obviously don't know that much about bike mechanics. Many of you have pointed that out. The only reason that I am even asking is that my bike seems to have many repeats of the same gear (like 1/7 feels the exact same as 2/4 and 3/1, etc.). I probably have less than five different feeling gear settings anyway. I don't want to change my bike to make it less versatile. I want to actually have a good amount of differentiating gear settings. I have done the basics with the gears like greasing them and such, but I don't really know how to do much else. I volunteer fixing up kids bikes, so I really have no experience fixing anything more complicated than a coaster brake. Sorry -- I realize I was really unclear before.

    Leah

  19. #19
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    watch this video and it will solve your problems and tell you why your bike is like this http://bicycletutor.com/gear-shifting/

  20. #20
    You gonna eat that? Doohickie's Avatar
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    Just... don't move your shifter so far.
    I stop for people / whose right of way I honor / but not for no one.



    Originally Posted by bragi "However, it's never a good idea to overgeneralize."

  21. #21
    Great State of Varmint Panthers007's Avatar
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    Don't mind these YeeHaws (myself included). Every newcomer gets razzed. The duplication of gears is a well-known and common phenomena. You can measure the gears on an inch-scale with a formula I can't currently remember. This helps to prevent this if you are re-building your drivetrain or just swapping out a cassette. Someone should come along with the formula.

    Here are a couple of resources to get you familiar with the basics of bike-mechanics. The first one is a series of short videos giving demonstrations of many situations:

    http://bicycletutor.com/

    And this is the venerable Park Tool repair site. Just point to a part/area on the bike, and you'll get instructions:

    http://www.parktool.com/repair/

    And finally we have the personal site of Sheldon "Our Lord" Brown. Until recently, the greatest living resource on all-things bicycle:

    http://sheldonbrown.com/harris/#articles

    This should give you a good background.

    Happy Trails!
    How do you keep an idiot in suspense?

  22. #22
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    Thanks
    I'm completely wiped today, but I'll definately get to work on fixing up my bike soon.
    Those sites look like they will be a lot of help.

    On a different note:
    Do you think a hybrid or a road bike would be better for someone who commutes 50+ miles per week in the city?
    I'm pretty uncertain about the future of my bike; I think it might be about time to trade up.

    Thanks again,
    Leah

  23. #23
    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by Leah View Post
    Thanks
    I'm completely wiped today, but I'll definately get to work on fixing up my bike soon.
    Those sites look like they will be a lot of help.

    On a different note:
    Do you think a hybrid or a road bike would be better for someone who commutes 50+ miles per week in the city?
    I'm pretty uncertain about the future of my bike; I think it might be about time to trade up.

    Thanks again,
    Leah
    50 miles a week is 10-ish miles a day... if you're riding every day. I cover 50 miles a week if I ride to work twice a week. (I heard of one lady who rides a 60+ mile round trip every day, then goes for training rides afterwards. Sheesh.)

    Ummm... are you unhappy with the way your current bike rides? Do you want to go faster? Are you bothered by other bike commuters beating you to the next stop light in the Red Light Grand Prix (a real issue here in Portland- some of the bike routes are getting jammed).

    IMO, if you're happy with your position on the bike, perhaps a swap for narrower, higher pressure tires would help. Your hybrid probably has 700 x 35C tires, so you could probably put 700 x 28C tires without a problem. Narrower tires could run into pinch-flat issues.
    Jeff Wills

    All my bikes.

  24. #24
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    Yeah, I'm car-free, so if I want to get somewhere, it is almost always on my bike. Add that to a 6-mile-per-weekday commute, and it definately begins to adds up.My main problem (other than the gear thing, of course) is that my bike is fairly heavy. I live on top of a gigantic hill, so anywhere I go involves getting back up it.My bike is definately worth the $250 I paid for it a few years ago, but that doesn't really mean much with a bike. I've been looking for a replacement on craigslist because I really don't have the money for a new bike, but not a ton has come up in my size. I've been weighing whether its cheaper to just fix up my bike or get a new one, and whether fixing it up would be worth the time and money anyway. So far, its been pretty inconclusive.

  25. #25
    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by Leah View Post
    Yeah, I'm car-free, so if I want to get somewhere, it is almost always on my bike. Add that to a 6-mile-per-weekday commute, and it definately begins to adds up.My main problem (other than the gear thing, of course) is that my bike is fairly heavy. I live on top of a gigantic hill, so anywhere I go involves getting back up it.My bike is definately worth the $250 I paid for it a few years ago, but that doesn't really mean much with a bike. I've been looking for a replacement on craigslist because I really don't have the money for a new bike, but not a ton has come up in my size. I've been weighing whether its cheaper to just fix up my bike or get a new one, and whether fixing it up would be worth the time and money anyway. So far, its been pretty inconclusive.
    Ah, I see...

    IMO, a conventional road bike would probably be a better hill climber than fixing up a hybrid. On the other hand, putting a lower stem and straight handlebars might be enough of a change to satisfy your hunger for hills. How well either bike fits you will be a key element.

    I know- pretty wishy-washy. "Inconclusive" is my middle name! (I think.)

    Talk to the local racing club- many times someone is trading up, down, or sideways for the latest "big thing". A "racing" bike might not be a good commuter, but you might luck out. An older road bike that fits you and accepts slightly fatter tires (as above- 700 x 28C) sounds like it would fit the bill.
    Jeff Wills

    All my bikes.

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