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  1. #1
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    mountain bike conversion

    I don't know very much about bikes but i had this idea for a bike I want to convert.

    I have this old mountain bike frame that I really like that I want to keep, but then I was wondering if I could attach a bmx gyro so i can spin the handle bars and change it to a single gear that is able to spin backwards too. Finally I want to add a disk brake in the back.

    All I want to know is any of these things possible and if they are how can I do them?
    thanks
    Last edited by benokkema; 06-15-09 at 01:08 PM.

  2. #2
    transformers fanatic dragsterIII's Avatar
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    Sure it could be possible, actually it would be really neat. Are the front sprockets multi-speed? If so you might want to convert it to a single if the you are going to a free single in the back. Just remove the cassette and install a single gear and change the the headset (the bolts and rings that keep the fork attached to the frame) to the BMX Gyro variety.

    I say go for it, post some pics of the Mountain bike.

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    Okay, thank you. And yes, the front sprocket is multi speed. My dad said he was going to help me with the conversion to single speed. I'll post some pictures shortly.

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  5. #5
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    Quote Originally Posted by benokkema View Post
    ..I have this old mountain bike frame .. I was wondering if I could attach a bmx gyro so i can spin the handle bars
    Form the assembly instructions I've seen, I don't think a BMX gyro will work on a threaded fork, which you have.

    Then again, BMX isn't my strong side. I could be wrong, or there might be gyros out there that will work on threaded forks. And, assuming its an 1 1/8" fork, (which it looks like) you could replace it with the more common aheadset-type fork used these days. Then fitting a gyro should be just as in the manual I've seen. Will require some more work and some more bits though.

    Quote Originally Posted by benokkema View Post
    ..I have this old mountain bike frame .. I was wondering if I could ..change it to a single gear that is able to spin backwards too.
    Not entirely clear what you want to do here. Looks like you have a 6-speed freewheel on there right now, in which case you should be able to fit a SS freewheel fairly easy. You'd have to either cold-set the frame, or get creative with spacers to fill up the drop out width probably. If you're looking to be able to pedal backwards a new hub that can take a lockring is recommended.

    Quote Originally Posted by benokkema View Post
    ... Finally I want to add a disk brake in the back.
    Probably your biggest challenge, unless your father can weld. That frame haven't got any disc brake mounting tabs. There are some adapters available, but they're generally rather kludgy looking. A rear disc brake would be another reason to look for a new hub/wheel.

    You should be able to keep your cranks. The chainrings you don't want can be unbolted. You might want to get rid of that biopace chainring in favor of a standard chainring with a tooth count more suited for singlespeeding.

  6. #6
    transformers fanatic dragsterIII's Avatar
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    Quote Originally Posted by dabac View Post
    Form the assembly instructions I've seen, I don't think a BMX gyro will work on a threaded fork, which you have.

    Then again, BMX isn't my strong side. I could be wrong, or there might be gyros out there that will work on threaded forks. And, assuming its an 1 1/8" fork, (which it looks like) you could replace it with the more common aheadset-type fork used these days. Then fitting a gyro should be just as in the manual I've seen. Will require some more work and some more bits though.



    Not entirely clear what you want to do here. Looks like you have a 6-speed freewheel on there right now, in which case you should be able to fit a SS freewheel fairly easy. You'd have to either cold-set the frame, or get creative with spacers to fill up the drop out width probably. If you're looking to be able to pedal backwards a new hub that can take a lockring is recommended.



    Probably your biggest challenge, unless your father can weld. That frame haven't got any disc brake mounting tabs. There are some adapters available, but they're generally rather kludgy looking. A rear disc brake would be another reason to look for a new hub/wheel.

    You should be able to keep your cranks. The chainrings you don't want can be unbolted. You might want to get rid of that biopace chainring in favor of a standard chainring with a tooth count more suited for singlespeeding.

    I agree with taking off the chainring and getting a new wheel/hub. the problem would be disc brakes. that would need a new hub or if you are not worried about drilling into the frame that would work

    actually some gyro headsets accept threaded mounts, I have an old Huffy that has these componenets.

    What kind of style are you going for, are you looking for practical or a tricked out bike, becouse you can do some cool things with forks
    Last edited by dragsterIII; 06-17-09 at 11:48 AM.

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    Gyro came out before anyone was doing 1 1/8" or threadless.
    And I'm guessing that when you're saying "single speed" you mean "fixed gear", because by "spin backwards" I think that you're saying that when you pedal backwards, the bike moves backwards.

  8. #8
    transformers fanatic dragsterIII's Avatar
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    Quote Originally Posted by mastershake916 View Post
    Gyro came out before anyone was doing 1 1/8" or threadless.
    And I'm guessing that when you're saying "single speed" you mean "fixed gear", because by "spin backwards" I think that you're saying that when you pedal backwards, the bike moves backwards.
    i think he means he still wants the free wheel to work

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    Quote Originally Posted by dragsterIII View Post
    i think he means he still wants the free wheel to work
    Well if that's the case then you can easily still do that with a multi-speed.
    Personally, I'd go with an average ring up front (42) and a tight freewheel in the back (a 6-7 speed, say 14-23)
    Also, unless you can do barspins, don't mess with a cable detangler, it'll just make the braking mushy and be hard to adjust.

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    Quote Originally Posted by dragsterIII View Post
    ... the problem would be disc brakes. that would need a new hub or if you are not worried about drilling into the frame that would work
    He'd need a new hub AND some work done to the frame. Drilling it isn't much of an option. Frame tubes are rather flimsy and need hard points added to take the strain of basically anything more loaded than cable stops.

    Quote Originally Posted by dragsterIII View Post
    ... actually some gyro headsets accept threaded mounts,
    What I could tell from the assembly instructions, a gyro adds some height to the headset stack. Threaded forks are usually cut to length very precisely, so trying to add a gyro afterwards might not leave enough threads for the locknut to engage. But sure, if there isn't any issues with clearance or stack height there's no reason why a gyro wouldn't work with a threaded headset.

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    Quote Originally Posted by dabac View Post
    What I could tell from the assembly instructions, a gyro adds some height to the headset stack. Threaded forks are usually cut to length very precisely, so trying to add a gyro afterwards might not leave enough threads for the locknut to engage. But sure, if there isn't any issues with clearance or stack height there's no reason why a gyro wouldn't work with a threaded headset.
    But the fact of the batter is that the ACS rotor and the Odyssey Gyro both came out in the mid 80's as a mod for existing bikes, and bikes at that time were all 1" threaded.

  12. #12
    transformers fanatic dragsterIII's Avatar
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    Quote Originally Posted by mastershake916 View Post
    But the fact of the batter is that the ACS rotor and the Odyssey Gyro both came out in the mid 80's as a mod for existing bikes, and bikes at that time were all 1" threaded.
    correct!

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    Quote Originally Posted by mastershake916 View Post
    But the fact of the batter is that the ACS rotor and the Odyssey Gyro both came out in the mid 80's as a mod for existing bikes, and bikes at that time were all 1" threaded.
    I never said that it couldn't be done, only that the assembly instructions that I've seen made it look like a rotor/gyro would add to the stack height of the headset, and that threaded forks are usually cut rather precise.
    If a rotor/gyro is mounted in a way that doesn't add height to the headset stack, then I'm obviously missing something in the assembly instructions, so please explain how they're put together then.

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    Quote Originally Posted by dabac View Post
    I never said that it couldn't be done, only that the assembly instructions that I've seen made it look like a rotor/gyro would add to the stack height of the headset, and that threaded forks are usually cut rather precise.
    If a rotor/gyro is mounted in a way that doesn't add height to the headset stack, then I'm obviously missing something in the assembly instructions, so please explain how they're put together then.
    What I'm saying is that they were designed as an accessory, at the time, no bikes cane with it, they were added on later. It certainly will take away a little bit of threading, but not much, and factory forks will give you enough extra thread to let you thread the locknut on most of the way. The locknut won't be able to go on all the way after, but it doesn't need to.

  15. #15
    Freewheel Burning GaryNoTrashCoug's Avatar
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    Therapy Components makes an adapter that mounts to the left canti stud on your seat stays, but as stated previously for the price, plus new disc-compatible hub, effort, etc.... you might be better off looking into a bike that is closer to what you want. No reason not to clean up and use that old school whip though. It would make a great beater commuter/utility bike!
    No Parole From Rock & Roll

  16. #16
    I am Noobert.
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    I think its a good canidate for single speed.

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