Rear cog on 2015 Kona Unit- Mtbr.com
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  1. #1
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    Bonking ... not feelin' well Rear cog on 2015 Kona Unit

    Decided to replace the 18t cog with a Surly 20t cog. So had an oversight on my part. When I took the cog off and replaced it with the surly 20t it seems that the spacers on the Kona are not large enough and it causes the cog to move around a few mm or so.

    Also, I didn't consider needing a new chain for this, will I?

    So, how do I tackle this?

    Thanks!

  2. #2
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    I know some brands of cogs are thicker metal. You might check out a niner cog. Otherwise you need to get your spacers to take up the slack so it doesn't mess up your hub. You can buy spacers inexpensively at most shops. Shoot they might just give you a hand full.

    I think generally the cheap cogs are thin and the more expensive cogs are thick.

  3. #3
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    You might want to consider a new chain if you can't move the sliders far enough forward, I wouldn't recommend adding links. Pick up a sram 8-speed chain or similar ~$15, keep the old chain around if you decide to go back to the 18t cog.

    You will need to re-adjust the rear brake caliper after the install

  4. #4
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    Yeah, some SS cogs are different. The Kick Ass cogs (are they still around?) wouldn't even fit on my hub in the first place (cog diameter was too small). Like TG-CO said, your shop should have some spacers for you for free/cheap.

    FYI - going from 32X18 to 32X19 should fit with the sliders slammed forward and same chain length, but only if the chain has been "stretched" by a few rides. If you're like me and a lot of riders, you'll want to minimize your chainstay length on a 29er single speed. Unless you use a half-link, 32/20 on a Unit puts the stays at 17.5" - not ideal IMO, but that's somewhat personal. I love my Unit at 32/19 with sliders slammed forward: great gear for lots of rides, minimized chainstay length at 17.1", and no fussing with a half link. But again, when chain is new, it'll probably be a hair too short for 32/19, so it needs a few rides at 32/18 before it fits without being too tight. If your adamant on running 32/20, you'll either need some kind of half link to make it fit (rendering a stay length of ~17.25"), or get use a longer chain and run 17.5" stay length (with one additional chain link than currently).

    I don't think you'll need to readjust the rear brake calipers on a Unit. I never do on my 2011. SSs require little maintenance, but you do need to eventually become intimately familiar with your dropouts, chain, and cogs.

  5. #5
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    The way the shop set it up was with the sliders as far back as possible, when I do the 20t with the new chain should I bring it as forward as possible?

    I feel like I'm not in shape enough to handle 19t (YET), so I'm gonna tackle the 20t. You gave me alot of unknown info that I certainly needed.

    I need to do more research on chain-stay length and effect.

  6. #6
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    Quote Originally Posted by Stopbreakindown View Post
    You will need to re-adjust the rear brake caliper after the install
    Not on a Unit.

  7. #7
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    Quote Originally Posted by Giorgioc722 View Post
    The way the shop set it up was with the sliders as far back as possible, when I do the 20t with the new chain should I bring it as forward as possible?
    OK, they could have put the sliders at either about 17.2" or 17.7". It sounds like they did the latter. Which is perfect for you, because if you go to 32/20, then you'll keep the chain length exactly as it is. Simply install the new cog, reinstall wheel, then readjust your dropout position. Because the 20t cog is slightly bigger than a 18t, the dropouts simply need to be set about .2" further forward (at around 17.5") in order to achieve proper chain tension. Let proper chain tension be your guide as to where to clamp down your dropouts. Be patient - getting everything lined up and tightened just right takes some practice if you've never done it.

    Quote Originally Posted by Giorgioc722 View Post
    I feel like I'm not in shape enough to handle 19t (YET), so I'm gonna tackle the 20t.
    Everybody finds their own way to make it up hills. For me, the critical thing is getting the h-bars up high, and not too far away, so I can nearly stand while climbing out of the saddle. This allows me to bounce/dance on the pedals, which I find very efficient. If my bars are lower than my saddle, I can't climb for crap.

    Quote Originally Posted by Giorgioc722 View Post
    I need to do more research on chain-stay length and effect.
    Unless you're very tall, or riding very fast, shorter is usually better. The Unit's 17.1-17.7 window isn't bad, but I definitely prefer trying to keep it in the shorter half of that range.

    You might find this link helpful:
    http://eehouse.org/fixin/formfmu.php
    It's a bit clumsy to learn, but helps predict your chainstay length.

  8. #8
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    Thanks man, this info is super valuable.

    An update, needed to get a new chain cause I was wrong about how the chainstay legenth was set.

    Cut the chain too short, part of the learning process? Haha.

    I got an sram 8 speed chain, noticed a single speed chain at the shop. I'm gonna pick up a new chain tomorrow.

    Would I be making a mistake by getting the single speed chain?

  9. #9
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    Quote Originally Posted by Giorgioc722 View Post
    Would I be making a mistake by getting the single speed chain?
    depends on what chain, depends on your setup, depends on personal preference.

    i bought a SS KMC chain and thought i was doing myself a favor. turns out it didn't play well with my NW chainring. it went in the trash and now all i use are 8 spd chains. simple, cheap, durable, and is compatible with most SS specific drivetrain stuff.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  10. #10
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    RE: Chains. 8 speed chains are cheap, work with everything. It's kind of the default answer but I think the consensus is that 10spd chains are lighter, stronger. That's probably your optimal choice. Depends on your cr, I think Surly requires 8spd or ss. I wonder if alloy cr's might like the tighter fit of the smaller chain a little better. But, I mess around with my gearing so much I just haven't been able to get away from the el cheapo chains just yet.

    RE: Spacers. BB spacers work fine as does 1 1/4 pvc pipe. And if you're all like ew that's too ghetto then get yourself over to Endless Bike (still around, still run by a dynamite single-speeding chick) and get your set of fibonacci sequence spacers, which is the most dork-tastic bicycle accessory pretty much ever. Still trying to figure that out but I think the thing is, you can adjust in 1mm increments using the fewest number of pieces possible. Instead of you know having a baggie full of greasy spacers of various origins like most of us probably have, you'll have these blingy precision bits in a velvet lined hardwood box. I guess.

    Thing is, women love single speeders, they'll gather around your bike and ask ya questions and stuff; tell you how pretty your bike is. When you pull out that fibonacci thing, it'll just blow their minds. You gotta consider these things. A certain amount of awesomeness will be expected of you. So yeah, forget the PVC pipe. My bad.

  11. #11
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    Quote Originally Posted by TampaDave View Post
    Thing is, women love single speeders, they'll gather around your bike and ask ya questions and stuff; tell you how pretty your bike is. When you pull out that fibonacci thing, it'll just blow their minds. You gotta consider these things. A certain amount of awesomeness will be expected of you. So yeah, forget the PVC pipe. My bad.
    wtf? are you still drunk from last night?
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  12. #12
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    Quote Originally Posted by TampaDave View Post
    women love single speeders, they'll gather around your bike and ask ya questions and stuff; tell you how pretty your bike is.
    I once met a beautiful girl while out riding on my snazzy SS (King hubs, Erikson post, Niner fork, etc.). When she saw I had 1 gear and no suspension, she pitied me, and told me about how I could get a geared full-suspension bike on Craigslist for about $60. I just nodded my head. She was a hiker, not a biker...

  13. #13
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    Be aware that a lot of ss chains are 1/8" width, mainly for BMX use. You want your chain to match your chain ring and cog, which I'm assuming are 3/32".

    I've always used a SS-specific chain (KMC Z610HX) on my bike. I thought non-SS chains were designed to provide more lateral play, in order to facilitate running high or low gears on a rear cassette. In contrast, SS chains maintain their integrity more, and so are less likely to fall off. I'm not sure if this makes an actual difference while riding, but I'd had great luck with the Z610HX, so I never considered using anything else.

  14. #14
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    if you just need a little extra spacer on the hub, see if the shop has a worn-out cassette that can be pulled apart- you can use the spacers that go between the cogs.

    8 speed chains should be fine. I have never found that a SS-specific chain is much better and 1/8" chains (made for bmx bikes and beach cruisers) slide around on the teeth.

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