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  1. #1
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    Help Understanding Cog & Lock Ring

    I'm a bicycle newbie in the truest sense and attempting to convert an old 10 speed to fixed (needless to say, this is a scary and often pathetic situation). I've spent some serious time reading through Sheldon Brown's articles and glossary and other informative sites, but I still can't seem to understand everything involving the cog/lock ring/sprocket. I'm getting a fixed wheel (from IRO) and don't understand how the cog and lock ring work and what the difference is between those and the sprocket and gears and hub?

    Anyone willing to explain?

  2. #2
    Retrogrouch in Training bostontrevor's Avatar
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    "Gear" is a generic term for a) any combination of chainring (big ring up front) and sprocket (ring out back)--thus 10-speeds have 10 "gears" like a car might have 3, 4, or 5 gears or b) it refers specifically to a sprocket or chainring. It's an umbrella term for those round things that have teeth for chains.

    Unlike most wheels today, a fixed gear wheel doesn't freewheel. There's no ratcheting mechanism that lets the gear spin. You probably knew this.

    A fixed gear hub differs from an ordinary freewheel hub in that it features two sets of threads. The first is nearest the hub body and is conventional right-hand threaded. You spin the cog on, righty tighty lefty loosey. However since the cog doesn't freewheel in reverse, it would just lefty loosey itself right back off without the lockring. There are a second set of threads that lie outboard the first set of threads. They are wound around a smaller diameter cylinder so that the cog can be passed over them without interference.

    The lockring threads are reverse threaded. The lockring threads on "backwards" and overlaps the cog so that under backpressure the cog will try to unthread and find itself pressing against the lockring which will, under the same forces, simply thread itself tighter.

  3. #3
    Iguana Subsystem dolface's Avatar
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    nice bt!
    someone put that in a sticky or faq or something.

  4. #4
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    Thank you for your swift and great reply! So, cog & lock ring = fixed gear hub? What's a decent price to pay for a fixed hub? What's the cheapest way to go about getting/making it?

  5. #5
    Iguana Subsystem dolface's Avatar
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    nashbar has fixed hub on sale for $30, which is an excellent price, but that's just a hub.
    if you want a wheel i think lots of folks here have been real happy with an iro wheel.

    http://www.irocycle.com/fixedgearand...einc/id67.html

  6. #6
    Retrogrouch in Training bostontrevor's Avatar
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    IRO's $100 rear wheel is hard to beat. It's a quality hub and quality rim for a price that's usually reserved for a level just above trash.

    Likewise, if you're just buying a hub it's hard to beat $40 for the IRO. It's solid and has cartridge bearings. I've never heard anything bad about its threads stripping. So basically it's a fine hub, especially for the price.

    edit: ok, at $30, the Nashbar hub's pretty harder to beat.
    Last edited by bostontrevor; 02-13-05 at 02:53 PM.

  7. #7
    troglodyte ryan_c's Avatar
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    cheapest != best.
    skimp on things like handlebar wrap or ride on patched tubes, but everyone here is going to tell you not to get the cheapest hub. do a search on "suicide hub" don't skimp where it counts.
    of course, i suppose if you have to skimp you have to skimp, and those methods can be reviewed with the above search.

  8. #8
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    Didn't you say that you've ordered the rear wheel from IRO? The iro rear wheel is a great deal for $100. You can't really make a fixed rear wheel unless you use the suicide method, aka the bumbike loctite method.

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    Even if I'm getting the fixed real wheel from IRO, I still need to get a cog and lockring, don't I?

  10. #10
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    Quote Originally Posted by sofikl
    Even if I'm getting the fixed real wheel from IRO, I still need to get a cog and lockring, don't I?
    Yep, but If you haven't ordered the wheel yet, ask tony at iro to include a cog and lockring, and he will for a few extra $$. I think it is $140 total shipped. (wheel, cog, lockring, shipping) You can ask him to mount the cog and lockring, saving you to have to do that.

  11. #11
    cyclist/gearhead/cycli... moxfyre's Avatar
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    If you are a complete newbie at bike mechanics, you may have difficulties even with a pre-built rear wheel. The main problem is that your chainline won't be straight. This means that the chain won't go straight from your chainring to your cog. This is DANGEROUS if it is too far off. There are a variety of ways to get your chainline right, but none are trivial.

    Maybe you have found this page already, but if not it's a very good step by step guide to building a fixed gear (also from Sheldon Brown's site): http://www.sheldonbrown.com/deakins/...onversion.html. I just built mine using this guide, and it was great.

    That page talks about chainline and some of the things you can do to get it right! Also, you'll want to think about the gear ratio you want before ordering your cog, otherwise you'll not like the gear you get and have to order a new $25 cog.
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  12. #12
    Member ImMilesDavis's Avatar
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    Tony is the man too! When I was putting together first fixed gear bike, he helped me out tons. He's super quick with the replies aswell. Any questions you have don't be affraid to ask him, he'll help you out, and he'll be honest with you.
    in the dust of the last design... I will take to the sky. FRODUS

  13. #13
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by ImMilesDavis
    Tony is the man too! When I was putting together first fixed gear bike, he helped me out tons. He's super quick with the replies aswell. Any questions you have don't be affraid to ask him, he'll help you out, and he'll be honest with you.
    Ya, I asked him for the hub dimensions at like 11 pm on a Sunday, not really expecting a reply for a day or two. Within half an hour, he'd not only gotten back to me, but made a web page with information on the hub dimensions. Now that's service.
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  14. #14
    pluralis majestatis redfooj's Avatar
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    yeah, when i made my fixed wheel purchase i started emailing him late night (CST! and hes in new york)... carried a few emails through the night and i ended up ordering a wheel, cross levers, and lockring

    i asked him whether a 17 or 18 cog would get my fit my chain & dropouts ... he threw both in for free so i could test them! (albeit they were basic junk)

    100$ for an IRO hub laced to Velocity rim is wayyyyyyyyyy better than the 90$ + 20$ shipping Sun/NoName & Suzue JR crap found on ebay

  15. #15
    Better than you since 83! junioroverlord's Avatar
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    Quote Originally Posted by ryan_c
    cheapest != best.
    skimp on things like handlebar wrap or ride on patched tubes, but everyone here is going to tell you not to get the cheapest hub. do a search on "suicide hub" don't skimp where it counts.
    of course, i suppose if you have to skimp you have to skimp, and those methods can be reviewed with the above search.
    Quiet you! I love my suicide hub though its days are numbered. Soon I will be a safe fixer with some nifty miche primato track hubs. Lockrings are for sissies!
    "Riding bikes on the street is the fuggin jam!" Juvi-Kyle

  16. #16
    Member Sweetwater's Avatar
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    Wow ... nice write-up, bostontrevor! That was educational (in a good way).

    Speaking of lock rings ... my lbs built my fixie from an old road bike and they told me that I'll need to come back to have the lock ring tightened every so often. Does this sound right? Can I do it myself? Does it matter that they built it with a Suzue SIL-SP hub (yeah, yeah)?

    Thanks!

  17. #17
    Cornucopia of Awesomeness baxtefer's Avatar
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    you'll probably want to tighten the lockring after you ride around for the first time.
    You can apply much more torque with your legs than you can with a chainwhip. so after your first ride your cog will probably be a bit tighter, and your lockring won't be completely snug up against it. thus the need to re-tighten the lockring.
    you can do it yourself, you just need the right tool. a BB lockring tool should work. just don't get the park one. it sucks.

  18. #18
    Member Sweetwater's Avatar
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    Thanks! It's been making a slight rattling sound from the drive train every so often ... I wonder if the ring is loose?

  19. #19
    Crapzeit! mcatano's Avatar
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    Quote Originally Posted by bostontrevor
    edit: ok, at $30, the Nashbar hub's pretty harder to beat.
    So hard to beat, in fact, that I think they sold out. I think the price is back up to $50 or $60 for the rear only.

    m.

  20. #20
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by mcatano
    So hard to beat, in fact, that I think they sold out. I think the price is back up to $50 or $60 for the rear only.

    m.
    Yep, I woulda bought one of them when it was at $30, but they only make a 32 hole version, and I'd like a 36. I even bugged there technical support dept to see if they would order some in 36H, but no response.
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