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  1. #1
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    fixed gear conversion from freewheel

    on sheldon brown's website it stated that it was possible to convert a freewheel to fixed gear for singlespeeding. i did not quite understand when he explained how to do it. i was wondering if someone could explain it to me in simpler terms or with pictures/diagrams or whatever? i hope to convert an old 7sp freewheel into a singlespeed fixed gear using a singlespeed freewheel and the conversion method. TIA.

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    You could weld it...........
    Je vais à vélo, donc je suis!

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    Let's clarify terms

    Single speed - can be fixed gear or single speed freewheel

    Fixed gear - the rear cog is "fixed" on the hub. There is no freewheel mechanism. No coasting, no backpedalling. If the wheel is turning the pedals are turning.

    If you want a single speed, just buy a single speed freewheel from Harris Cyclery or your LBS, remover your multi-speed freewheel, screw on the single speed freewheel, shorten the chain. As long as it is a freewheel you can still route the chain through the derailleur as long as you adjust the derailleur to stay in one place. Probably easier to take the der off and shorten the chain.

    If you want a minimalist conversion to fixed gear order a track cog and a bottom bracket lockring. Screw on the track cog good and tight then screw on the lockring and tighten the two against each other as you do with cup and cone bearing locknuts. Use blue Loctite on both the cog and the lockring and LOCK THEM UP TIGHT. The stress of stopping with a fixed gear can be more than pedalling, and you can easily unscrew everything. Not good while riding.

    Better is to get an inexpensive wheel with a flip flop hub, track cog, and track lockring (left-hand threads). One side is threaded normal for a track cog and left handed for the lockring. These will withstand the forces of stopping better. Quality Bicycle Products (QBP) sells a very nice one that you can get through your LBS for about $100.

    If you are actually talking about trying to fix the freewheel pawls to make a multi gear freewheel fixed I wouldn't recommend it. If you are a knowledgable bicyle mechanic and a knowledgable welder you could probably figure it out. A single speed freewheel only costs about $20. Track cog and bb lockring about $30. Add another $100 for a proper wheel for the best solution.
    If it ain't broke, mess with it anyway!

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    so take off the freewheel, replace with a singlespeed cog freewheel, then use a BB lockring to lock the cog down and then use locktight on the threads? i've worked with bb's before but which part is the lockring and how can it be used to lock down the freewheel? do you mean the lockring that is on my current freewheel right now? the one that comes off with a bb tool? and how does that make the setup a fixed gear? wont it still be able to backpedal? maybe i'll understand it better when i take everything apart in person.

    also sheldon brown's site mentioned re-dishing? is it necessary?

  5. #5
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    tFunk -

    Let's make sure you are on the right page as far as terminology goes:
    Freewheel - a gear or cluster of gears with the ratcheting mechanism built in. It is threaded to mate to a threaded hub.

    Freehub - a spline unit on a hub that contains the ratcheting mechanism. A cluster of gears, which is also splined, slides over this unit. The gears themselves do not have the ratcheting mechanism. Neither piece is threaded.

    If you do indeed have a freewheel hub, you can screw on a FIXED COG (not a freewheel). It has the same threads as a freewheel but does not have a ratcheting mechanism. this means that when the wheel moves the pedals also move - no coasting. An English threaded BB lockring can be used to secure. Most bikes these days don't use these. You can get one at your LBS or check www.thethirdhand.com Alternately, uou could also spin on a BMX freewheel and use it as a single speed. No lockring is necessary.

    If you have a cassette wheel, you can make it a single speed but not a fixed gear. Break apart the cassette, get some extra spacers, use one cog and the spacers to get things lined up properly. Step by step instructions here

    Redishing? stick the wheel in the frame and you will know right away, but 99% of the time you will have to.

    You need to verify that you have a freewheel hub and not a freehub and you also need to get a fixed cog instead of a singlspeed freewheel if you really want to build a fixed gear.
    Single Speed Outlaw
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  6. #6
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    If you do have a cassette style wheel, you can make it fixed by getting the freehub welded. I have one of these and would be willing to sell it(welded freehub body). Be forewarned that this will not work well with a standard quick release axle. Trust me I know, but it MAY work if you used a solid axle with bolts like a regular fixed gear bike. I had one welded up for testing and had some problems with it while using a quick release so I abandoned the fixed and bought a bmx freewheel for my old threaded wheel which used a 7 spd freewheel. Let me know if this is something you would be interested in. I can also take pictures if anyone wants to see how it looks or explain in more detail the problems I ran into.

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    i actually am already riding a freehub singlespeed. my questions are for a freewheel conversion.

    when i thread on a freewheel singlespeed cog it will just unscrew when i backpedal, correct?

    to stop this i must use a english thread bb lockring? is that english bb lockring the same lockring that is holding my current 7sp freewheel onto the hub?

    would a bmx freewheel thread onto a freewheel? do i need a lockring with a bmx freewheel?

    and when you said redishing, how is that done? is it something i can do at home or pretty easy to learn? tools? how much tools cost?

    how much will a bmx freewheel cost? i know singlespeed freewheels are ~<$20. well enough questions for now, thanks to those who've replied!

  8. #8
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    tFUnk,

    First I recommend you check out these two forums for some good S/S information.

    1. http://forums13.consumerreview.com/crforum?14@@.ee7b974

    2. http://forums.consumerreview.com/crf...82.3VKNagc9pYA^0@.efbc183

    From them you will find a lot of information to answer all of your questions. I think some things are still getting confused with regards to freewheel vs. freehub/cassette.

    Freewheels: They generally are a 6spd or 7spd cogset with its own built in ratcheting mechanism and is one complete assembly. It screws on to a hub clockwise with normal threads that are similar to what bmx bike freewheels use. Hubs that use freewheels that screw or thread on to the hub can also accept a bmx freewheel (not fixed). I did mine using a small spacer on the inside of the freewheel to help move it further out for a better chain line with out messing with axle spacing or wheel dishing.

    Freehubs: They typically accept 7spd, 8spd or 9spd cassettes. The freehub is attached to the hub and has its ratcheting mechanism inside the freehub. Upon the freehub is a cassette which is a group of cogs and spacers which may be attached together or may all be seperate. They will use a lock ring that torques down on the smallest cog of the cassette to keep it all together. Many people make S/S wheels by installing a whole bunch of spacers and only one cog properly aligned with the chain ring and lock it all down with the lock ring. In this configuration you have a freewheeling Single Speed.

    >when i thread on a freewheel singlespeed cog it will just >unscrew when i backpedal, correct?

    I haven't personally tried this but from what I have read people seem to get this method to work quite well.

    >is that english bb lockring the same lockring that is holding my >current 7sp freewheel onto the hub?

    This is confusing, this makes me think you are using a cassette with a lock ring but you stated freewheel. If your first statement is correct and you are using a freehub than no the lockring on a bottom bracket is not the same as what you are using.

    >would a bmx freewheel thread onto a freewheel? do i need a >lockring with a bmx freewheel?

    No, No. A bmx freewheel will thread on to a hub that uses a 7spd freewheel but not a hub that uses a freehub/cassette setup. If you use a bmx freewheel on the proper type hub you won't need a lock ring since there will be no need since the freewheel will not be fixed. Hence you could backpedal.

    >and when you said redishing, how is that done? is it something i >can do at home or pretty easy to learn? tools? how much tools >cost?

    Redishing would only be required if you change the spacers on the wheel to adjust the chain line. This would then cause the wheel to sit closer to one side of the frame. To redish the wheel you would have to loosen the spokes on the side that is closest to the frame and tighten them on the other side to make it correct. This would all be done methodically like 1/2 turn loose one one side and 1/2 turn tight on the other and recheck for proper alignment. Continue this till it is good but maybe drop to 1/4 turn each side.

    BMX freewheel should cost about $20 but I don't think that is what you need.

    Finally take a look at this page on Sheldon Brown's site. It has some good pictures which should clarify the freehub/freewheel debate and cassette confusion.

    http://www.sheldonbrown.com/k7.html

    Good luck

    John

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    Hi,

    i think the main misunderstanding is because i stated that there is a bb lockring on my 7sp freewheel. since i have never taken apart a freewheel before i do not know the assembly of it. i think the point all of you have been trying to make to me is that a freewheel does not use a lockring to keep it on the hub, correct? that a freewheel is simply a cluster that threads onto the hub and threads off by using a freewheel remover tool (in my case i will use a bb tool because the grooves and notches line up).

    if that's the case, then what i mean to say is that my bb tool fits into my freewheel and i can remove the freewheel by using the bb tool. sorry for the terminology mixup there.

    i actually just finished my freehub ss project a few days ago using a 7sp freehub, spacers, and an 18t cog, and everything is held by a lockring. so i am not confusing freehub and freewheel.

    so my goal now is to make a ss project out of a freewheel, so i will either use a bmx freewheel or a singlespeed freewheel (are they just different terms for the same thing???). and i take it that a freewheel cluster has the backpedaling mech, while a singlespeed freewheel or bmx freewheel does not allow for backpedaling? since this is the case, pedaling backwards will cause the freewheel to unthread correct? what are some methods preventing this from happening? also, is it possible to space the singlespeed freewheel towards the outside (like how i used spacers on the cassette body to space my cog to the outside)? is this done by dishing the wheel?

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    so i think what i need to convert freewheel type wheel to singlespeed is to just remove my 7sp cluster, install a 1sp freewheel, put on a left threaded bb lockring, then try and get a good straight chainline.

    if this sounds incorrect let me know. also anyone have a pic of a bb lockring i dont know what it looks like. i've installed bb's before but don't recognize which is lockring. thanks

  11. #11
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    Now we are getting somewhere....

    >so i will either use a bmx freewheel or a singlespeed freewheel >(are they just different terms for the same thing???).

    BMX freewheel is just that it is a single cog on a FREE wheeling mechanism. Meaning that it is not fixed so if you want to make your bike fixed you need to get a "track cog". A track cog is a single cog similar to the one you used on your freehub project except it has threads on it as apposed to the cut out secitons for the splines on a freehub body.

    You may be able to place a small spacer over some of the threads on the threaded hub before you screw your new "track cog" on the hub. Then you may want to try a bottom bracket lock ring which is the small ring on the (non drive) left hand side of the bottom bracket. It is what is used to lock the adjustable cup of your bottom bracket. Unless of course, you have a new fangled cartridge bottom bracket which doesn't use a lock ring, then you would be confused and not know what the heck we are talking about.

    Once you have managed all of this you will need to correct your chain line which would be the most difficult part. You will likely need to use your chainring on the inside vice the outside and may need to remove some of the spacers from the right side of the axle and move them over to the left side of the axle. This would then make the rear wheel closer to the right side of the frame which would require you to redish the wheel.

    >is it possible to space the singlespeed freewheel towards the >outside (like how i used spacers on the cassette body to space >my cog to the outside)?

    Possibly, but just a little, the threads are quite small in comparison to the freehub body size. You only have about 3/4" of threads to work with so your cog will be way to the inside of the wheel once you get a track cog threaded on there which is why you would need to redish the wheel. This is where it would maybe be better to get a hub which is designed for this application. They make flip flop hub which allow freewheel single speed on one side and fixed track cog on the other using a proper left hand threaded lock ring which will prevent the cog from unscrewing itself. However I am sure you want to give this some testing before you plunk down the money to make a fixed gear wheel that you can't stand. I know I would.


    John

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    Check out the Phil Wood hubs on this page and note the threads which is what you will see when you remove the freewheel from your wheel. Also note the lock ring a few photos down this is similar to what you would want.

    http://www.sheldonbrown.com/harris/fixed-hubs.html

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    ahh thanks.

    now i really should think about this project. forget the bmx freewheel i want fixed cog because i want to be able to brake by back-pedaling. yeah seeing how the threaded fixed cog will be too far in toward the hub the chainline must be really messed up. reason i was planning on doing this is to salvage my old parts, a hideous specialized m2 frame (some may recall the threads i posted earlier on this frame) that probably has a misaligned rear triangle, and a 7sp freewheel wheelset. i want to be able to brake by backpedaling just like the old days on my 20" wheeler and make skid marks . might be too much trouble than it's worth though, i just finished building my freehub SS and it's a lot of fun to ride!

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    If you do indeed have a freewheel hub, you can screw on a FIXED COG (not a freewheel). It has the same threads as a freewheel but does not have a ratcheting mechanism. this means that when the wheel moves the pedals also move - no coasting. An English threaded BB lockring can be used to secure.
    Warning-a same-direction lockring must be very, very tight. Even then, it may still release unexpectedly! A fixed-gear hub has opposing threads to pevent this from happening. Should you decide to try this english-lockring idea, I would advise you to use some form of Locktite on the threads, to keep it from releasing when backpedalling.
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  15. #15
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    tFunk:

    It sounds to me like you are looking for a coaster-break set up, not a fixed-gear.....

    i want to be able to brake by backpedaling just like the old days on my 20" wheeler and make skid marks!

    A fixed-gear drive train will not allow you to coast at all, and if you pedal backwards, the wheel turns backwards. There is no breaking mechanism -- your legs to the braking.

    A coaster brake system (like on my old 20" bike) will allow you to coast, and if you start to pedal backwards a brake in the hub engages, often locking the rear wheel for cool skids......

    If you are indeed looking for a coaster brake rig, you will need a new hub.

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    Originally posted by SpotmaticF
    tFunk:

    It sounds to me like you are looking for a coaster-break set up, not a fixed-gear.....




    A fixed-gear drive train will not allow you to coast at all, and if you pedal backwards, the wheel turns backwards. There is no breaking mechanism -- your legs to the braking.

    A coaster brake system (like on my old 20" bike) will allow you to coast, and if you start to pedal backwards a brake in the hub engages, often locking the rear wheel for cool skids......

    If you are indeed looking for a coaster brake rig, you will need a new hub.
    good point

  17. #17
    Mr. Cellophane RainmanP's Avatar
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    D*Alex is right. If you decide to screw a threaded cog onto a freewheel hub and use a bb lockring to secure it, the two MUST be locked up VERY tight. This cannot be over emphasized. The force of resisting the forward motion of fixed gear cranks is very great and will unscrew even an apparently securely locked cog in an instant. I have a fixed/free flip flop hub with the preferable thread setup, right hand normal freewheel thread for the cog, left hand thread for a track lockring on one side. The other side is normal freewheel threading all the way. When I got the shop to put the next smaller cog on the track side I had them put the old cog on the freewheel side with a bb lockring (their suggestion). I still haven't had the courage to even try it. A hub that will take a true track lockring is really the best way.

    In response to your earlier question, which may have been answered already. Freewheel threads happen to be the same as English bottom bracket so using lockring just happens to work. It is not the same as the freewheel lockring and has nothing to do with your existing bb.

    And you MUST use a nutted axle. You simply cannot get a quick release tight enough to resist those same forces. And the nuts must be tighter than you think they need to be. I thought mine were tight enough, but after a few miles the wheel had moved enough to throw the chain - not fun at all on a fixed gear.

    Sorry for recovering some old turf. Some of the concepts in bike mechanics are very simple - once you understand them. But initially it can be hard to get a handle on them. It probably took months before I finally understood the whole freewheel/freehub/cassette issue.
    If it ain't broke, mess with it anyway!

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    i think instead of running fixed gear i will just put a bmx freewheel on it instead. guess i can't brake by pedaling backwards . thanks for the responses and sticking with me through all my confusion/assumptions .

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