Help with gearing...- Mtbr.com
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  1. #1
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    Help with gearing...

    Hi Gents,

    I'm hoping for some advice on gearing. I'm a clyde who was geared pretty low for riding in the Utah moutains. 32 up front 22 in back. I just moved to Illinois and need a new gear ratio that will be better on the flat. I'm looking to change out my rear cog as I'd like to keep the 32 up front for no other reason that I bought a nice one and don't want to have to change it.

    I was hoping for recommendations on what to put on back for riding in Illinois with a 32 front. I'm frankly not that experienced a single speeder. 16? lower? any ideas? I want something that will be fairly fast on gravel trails, and sometimes pavement, but hopefully still low enough to enjoy riding occasional single track in Wisconsin. Thanks for any help!

  2. #2
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    couple of questions. are you on a 26er, or 29er? what's your rear hub? are you using cogs on a freehub or a freewheel on the rear hub? EBB, sliders, or a tensioner?

    i'm not real familiar with that terrain but it sounds like you need two gear ratio's. one for singletrack and one for gravel/road.

    I'm 210 lbs and ride pretty technical, rocky, rooty terrain, with typical hills. i ride 32:18 on my rigid 29er. it's great on single track, but useless when commuting anywhere on pavement or anything flat.

    it's tough to say if you could find a gear that could do both. it really depends on the hills near you. 32:16 could be a good gear. it's probably not enough on flat ground or gravel roads though.

    for reference, i can tell you that most SS cyclocross bikes (like gravel bikes) use a 39-42:16-19 gear ratio. it works pretty well for commuting too.

    if you use single cogs you could buy a couple cheap ones to try a few different gear ratio's before you commit to a nice one. (if you do, purchase an extra quick link or two so you don't have to keep splicing pieces of chain together.)

    you could also try a "Dingle speed". google it. may work depending on your setup.

    as always you can check out Sheldon Brown's gear calculator for comparing gear ratio's.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

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

  3. #3
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    Thanks for your response. I'm on a 29er. Not totally sure about the rear hub but I think it's a freewheel. I believe its a tensioner, as I use screws that push the wheel back to add tension? This is a cheap Motobecane single speed.

    My guess is I'll want to lean toward a higher gearing, as I don't think there are many hills around. If I want to get close to a commuting gear it seems Like I'd want to do something lower than a 16 on back. Right now I'm thinking to try this in 14t:

    ACS Crossfire Freewheel > Components > Drivetrain, Brakes and Pedals > Singlespeed Cogs and Freewheels | Jenson USA

    But maybe a lower? Not sure...

  4. #4
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    Before you buy anything, show us a picture of your rear cog/hub. We can help make sure you buy the correct parts.


    32:18 is a pretty good gear and isn't too bad for tooling around town if you're not in a hurry. You've gotta be pretty damned fast to trail ride 32:16 in most places.

    Quote Originally Posted by monstertuba View Post
    Thanks for your response. I'm on a 29er. Not totally sure about the rear hub but I think it's a freewheel. I believe its a tensioner, as I use screws that push the wheel back to add tension? This is a cheap Motobecane single speed.

    My guess is I'll want to lean toward a higher gearing, as I don't think there are many hills around. If I want to get close to a commuting gear it seems Like I'd want to do something lower than a 16 on back. Right now I'm thinking to try this in 14t:

    ACS Crossfire Freewheel > Components > Drivetrain, Brakes and Pedals > Singlespeed Cogs and Freewheels | Jenson USA

    But maybe a lower? Not sure...

  5. #5
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    I think maybe you both are right about 32:18. I actually have an 18 that was originally on the bike with a 42 up front. I may as well try that since I have it but it is my understanding that I'll have to bring it in to a bike shop to have it pressed on. So I was hoping to get it right the first time. I'll just need to do some trial and error figure out what I'm actually going to be riding, but may as well start with what I have. Thanks for your responses. I'll post a pic just so y'all can educate me on the terminology for what I have.

  6. #6
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    I agree 32/18 can go well around town. I ride with an average of 20-21-ish km/h on my Unit with that gearing on tarmac. I thought it would be too low, but being a mountainbike with fattish tires, it's not that bad. I had 36/16 on a commuter, also MTB, but it was too high for me.

  7. #7
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    Quote Originally Posted by BENKD29 View Post
    as always you can check out Sheldon Brown's gear calculator for comparing gear ratio's.
    Stop it! Sheldon Brown was an awesome dude with amazing bike knowledge, but all you need to do is divide the chainring by the cog and compare the two ratios. Wheel size and crank length are totally irrelevant when changing gear ratios on the same bike since those stay the same.

    Here, I'll do it for you:
    32/22 = 1.45
    32/18= 1.78

    Swapping the 22 for an 18 will spin the rear wheel 23% further per each revolution at the crank.

  8. #8
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    yup, more than one way to skin a cat.

    i like directing people to Sheldon Browns page because it's a great resource for new people looking to learn. it has a lot more to offer than just gear ratio's.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

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

  9. #9
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    My advice is to get 18,19, and/or 20 tooth cogs. Using sizes smaller then 18 off road is a bad idea because the chain does not have as many teeth to engage. On road you can go down to around 14 tooth because there is less bounce but even so the larger cogs tend to do better. I have a lot of cogs in my collection but rarely use anything smaller then 17 tooth or larger then 20 tooth.

    On the front I really like having a 104 BCD spider because it is easy to swap the chainring. In addition since you are not removing and reinstalling the cranks you don't wear the threads on the expensive items. Overtime you can collect various chainrings until you have all the sizes from 32 to 36 tooth in your collection. If you have a single speed CX, gravel, road, or track bike you need more chain rings up to 54 tooth or even larger. Traditional style cranks that use standard bolt circles may be slightly heavier then spiderless options but it's much easier to setup the perfect combo.

    Once you have everything, you decision for the "ideal" gearing comes down to picking a combo that fits for your fitness level, goals, and terrain.

    For my 29er, I run 34/18 or 19 most of the time. For races in mountains I run 32/20. Flat races may see me on 36/18 or if it is mostly fire road I might go 36/17. On the road bike I run 54/18 for fast group rides. My cyclocross bike is on 44/20 right now.

    My wife's bike is running 30/19 right now because she needs a lower range and as such the smaller chainring is helpful (we are using Race Face spiderless cranks on her bike). If she were on cranks with 104 BCD, I would simply use 32/21 but, 21 is one of the few cog size that I don't currently own.

    It's nice to have a lot of options.

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