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  1. #1
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    Gearing question on my ss

    So yesterday I rode in my first ever mountain bike race. It was a 6 hour endurance race. I ride a 16 x 32 cog jamis exile 26er.

    It was great to see a larger population os fellow single speeders there, and I enjoyed talking to as many as I could. However when asked my ratio, to my surprise, they guys all said: "wow! On this course? That's crazy!"

    The course was very hilly, very roots with occasional rock gardens. I was the only 26er out there, but they all suggested going bigger, at least on the rear cog by 2 to 3 teeth

    Do why is having bigger cogs better to take on a very hilly course? I did think that 16 is smallest you can go so what do y'all think? Also a lot of the guys said that they have multiple cogs for different courses. Good idea?

    ETA: I do find I can fly on flatter flowing trails with my current set up, and really struggle on climbs. I thought it was tied to my endurance levels, there were other suggestions on other upgrades like wider handle bars with sweep and a shorter stem. Better tires and rims too.

    Might as well buy a new bike with all that I need to change. Not a bad idea. Hmmm
    Last edited by MadMacMan; 01-13-2013 at 02:06 PM.

  2. #2
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    Going bigger on the rear cog, gets you a lower gear. Going bigger on the chainring, gets you a higher gear. Gears are by the inch. You are in a 52inch gear. If you go to a 18t cog, it would change to a 46.2inch gear.

  3. #3
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    Ah. So I've really been over stressing myself by trying to clean hills. New cog next on buy list

  4. #4
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    1 tooth in the back is like 2 teeth up front in terms of gear ratios. I use a 34 up front and have a 18,19,20 for the rear. The 34-19 would be my optimal every day gear for the 29er. I'm fairly new to the single speed game but I now once you get to small on the rear cog it looses its efficieny.

  5. #5
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    Gear-inches are a great metric to compare the relative change of going from one gear ratio to another on the same bike. But if you want to see (in mathematical terms) the effect of changing wheel sizes or crank arm length, I really recommend Sheldon Browns Gain Ratio calculation:
    Gain Ratios--A New Way to Designate Bicycle Gears

    Online Calc:
    Sheldon Brown's Bicycle Gear Calculator

    For example, you can see that all else being equal, just going from 26er to 29er results in a bike thats ~10% harder to pedal. This really helps if you want to go from a 26er SS to a 29er SS and try to get the same feel for the gear ratios.
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  6. #6
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    Quote Originally Posted by PoisonDartFrog View Post
    Gear-inches are a great metric to compare the relative change of going from one gear ratio to another on the same bike. But if you want to see (in mathematical terms) the effect of changing wheel sizes or crank arm length, I really recommend Sheldon Browns Gain Ratio calculation:
    Gain Ratios--A New Way to Designate Bicycle Gears

    Online Calc:
    Sheldon Brown's Bicycle Gear Calculator

    For example, you can see that all else being equal, just going from 26er to 29er results in a bike thats ~10% harder to pedal. This really helps if you want to go from a 26er SS to a 29er SS and try to get the same feel for the gear ratios.

    I'll have to check out the gain ratios later but as far as I can see gear inches transcends wheel sizes, tire sizes, bicycle types, etc. and is pretty straightforward.

  7. #7
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    Quote Originally Posted by J.B. Weld View Post
    I'll have to check out the gain ratios later but as far as I can see gear inches transcends wheel sizes, tire sizes, bicycle types, etc. and is pretty straightforward.
    BINGO

  8. #8
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    Quote Originally Posted by MadMacMan View Post
    So yesterday I rode in my first ever mountain bike race. It was a 6 hour endurance race. I ride a 16 x 32 cog jamis exile 26er.

    It was great to see a larger population os fellow single speeders there, and I enjoyed talking to as many as I could. However when asked my ratio, to my surprise, they guys all said: "wow! On this course? That's crazy!"

    The course was very hilly, very roots with occasional rock gardens. I was the only 26er out there, but they all suggested going bigger, at least on the rear cog by 2 to 3 teeth

    Do why is having bigger cogs better to take on a very hilly course? I did think that 16 is smallest you can go so what do y'all think? Also a lot of the guys said that they have multiple cogs for different courses. Good idea?

    ETA: I do find I can fly on flatter flowing trails with my current set up, and really struggle on climbs. I thought it was tied to my endurance levels, there were other suggestions on other upgrades like wider handle bars with sweep and a shorter stem. Better tires and rims too.

    Might as well buy a new bike with all that I need to change. Not a bad idea. Hmmm
    By your thumbnail, I recognized that jersey. You're talking about the race at tyler. I used a 28:18 on a 29er which works out to roughly 32:19 on a 26er. So your gearing was a little steep.

    I (Grant, 3rd in the SS class) ran a 28:18 and Richard (1st in the SS class) ran a 32:18 and complained his gear was too big. We both ride 29ers, so there's some math to be done to convert that into 26er gears.

    Feel free to PM me on gear selection for the DFW trails, I don't have them all figured out, but I'm willing to help where I can.
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  9. #9
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    Big Pig Kick Cancers A$$. Tyler State Park is a great trail. Definitely invest in more cogs.
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  10. #10
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    Quote Originally Posted by J3SSEB View Post
    Big Pig Kick Cancers A$$. Tyler State Park is a great trail. Definitely invest in more cogs.
    If money is no object get the niner rdo cog

    if money is kind of an object get King cogs

    realistically buy surly cogs, Im pretty sure thats what +70% of SSers use.
    Something wrong with your bike? Blame it on super human strength and sleep well at night knowing you are more than a man.

  11. #11
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    Quote Originally Posted by ZXFT View Post
    By your thumbnail, I recognized that jersey. You're talking about the race at tyler. I used a 28:18 on a 29er which works out to roughly 32:19 on a 26er. So your gearing was a little steep.

    I (Grant, 3rd in the SS class) ran a 28:18 and Richard (1st in the SS class) ran a 32:18 and complained his gear was too big. We both ride 29ers, so there's some math to be done to convert that into 26er gears.

    Feel free to PM me on gear selection for the DFW trails, I don't have them all figured out, but I'm willing to help where I can.
    If tapatalk would let me give pos rep from my iPhone, I'd give it. I don't get to the DFW area as much as I would like, my parents and sister live there, so when I come, I'll be packing the bike.

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    Another DFW single speeder here. A lot of the SS guys on this forum ride some steep and long stuff, but around DFW, I find that the gear that gets me around the trail faster is just low enough for me to stay "on top of the gear". It's that moment as you come out of a corner and either grunt a little too hard, or just lay the power down and get back up to speed that makes a ton of difference. Gearing is definitely a personal choice. On a 26" bike, 32:16 is great for places like RCP for most people. Some of the hillier / twistier courses make a slightly lower gear a much more efficient choice.
    Last edited by OneBadWagon; 01-14-2013 at 12:32 AM.

  13. #13
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    Quote Originally Posted by J.B. Weld View Post
    I'll have to check out the gain ratios later but as far as I can see gear inches transcends wheel sizes, tire sizes, bicycle types, etc. and is pretty straightforward.
    Wrong! Wheel size obviously matters.
    My rides:
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  14. #14
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    Quote Originally Posted by ZXFT View Post
    If money is no object get the niner rdo cog

    if money is kind of an object get King cogs

    realistically buy surly cogs, Im pretty sure thats what +70% of SSers use.
    I've got some nice cogs, but either a Surly or On One cogs have worked just as well.

    I've been pretty impressed with On One Groove Armada cogs, especially for the price. Looks like they're out of the bigger sizes right now.

    On-One Groove Armada Single Speed Sprocket

  15. #15
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    Quote Originally Posted by serious View Post
    Wrong! Wheel size obviously matters.
    Not sure if sarcasm, but it does.

    We have heard it all before: 29er is ~11% bigger than 26er, so all else equal, they will require ~11% more torque to pedal than a comparably geared 26er. So, 32x16 on a 26er is about the same as 32x18 on a 29er. Similarly, 32x16 on a 29er will be a little harder to pedal than it is on a 26er... etc. etc.

    I know most people prefer Gear-Inches; certainly nothing wrong with that, and it's what I use to compare gearing on between bikes with the same wheel size. Gain Ratio is just another tool out there that lets you see the effect of not only different gear ratios, but different gear ratios along with different wheel sizes, and to a much smaller extent, crank arm length. It's always nice to have more tools...
    Mind your own religion.

  16. #16
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    Quote Originally Posted by PoisonDartFrog View Post
    N

    I know most people prefer Gear-Inches; certainly nothing wrong with that, and it's what I use to compare gearing on between bikes with the same wheel size.
    I'm pretty you can compare different wheel sizes with gear inches. Gain ratio just adds crank length to the mix.

  17. #17
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    Quote Originally Posted by TManiac View Post
    I'm pretty you can compare different wheel sizes with gear inches. Gain ratio just adds crank length to the mix.
    Correct, gear inches takes into account the wheel size as well as tire size.

  18. #18
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    Quote Originally Posted by stremf View Post
    Correct, gear inches takes into account the wheel size as well as tire size.
    Yes, Even if you run a 52 inch rim a gear inch chart will give you the correct #'s for the right chainring and rear sprocket combo. The 52 incher I used to have had no gears whatsoever and the calculation still works- 52 gear inches!

  19. #19
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    Quote Originally Posted by PoisonDartFrog View Post
    Not sure if sarcasm, but it does.
    Of course it does.

    But J.B.Weld said "I can see gear inches transcends wheel sizes" and the definition of transcend is "to exist above and independent of". But now I see he did not mean "independent of". Sorry about that.
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  20. #20
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    A 50 inch overall ratio is 50 gear inches regardless of wheel size. Different wheel sizes obviously require a different chainring/sprocket ratio to achieve the same gear inches, but 50 gear inches on a 26" is quite accurately as hard to pedal as 50 gear inches on a 29er.

    Except for one small thing: if a larger tire rolls over rough stuff easier, then the bicycle is a bit easier to pedal. But that's not a mathematical difference that could be compared as easily as leverage of the cranks and wheel size and gear ratios.
    Last edited by Saul Lumikko; 01-16-2013 at 07:31 AM.

  21. #21
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    Im not a gear guru, nor do I play one on tv.
    So if I go to a larger chain ring and rear cog on my 26er, I should move to a comparable set of rings when I upgrade to a 29er?

  22. #22
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    Quote Originally Posted by stremf View Post
    Correct, gear inches takes into account the wheel size as well as tire size.
    You're right - my recollection of the Gear-Inch equation was incorrect. Sorry about that.

    https://en.wikipedia.org/wiki/Gear_i...ng_gear_inches
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  23. #23
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    Quote Originally Posted by MadMacMan View Post
    Im not a gear guru, nor do I play one on tv.
    So if I go to a larger chain ring and rear cog on my 26er, I should move to a comparable set of rings when I upgrade to a 29er?
    32:16 on a 26er is about 32:18 on a 29er.

    The calculation is (front chainring/rear cog)*diameter of the wheel.

    For example: (32/16)*26=52" and (32/18)*29= 51.5"

    However, gear inches are not how far your bike travels in one revolution of the cranks. That number is equal to (gear inches)(π).

    Gear inches are an outdated, but widely used and helpful tool to determine equivalent difficulty of gears between different ratios and sizes of wheels.
    Something wrong with your bike? Blame it on super human strength and sleep well at night knowing you are more than a man.

  24. #24
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    I also remembered gear inches incorrectly. I deleted the mis-information from my previous post.

    Quote Originally Posted by MadMacMan View Post
    So if I go to a larger chain ring and rear cog on my 26er, I should move to a comparable set of rings when I upgrade to a 29er?
    If you switch to a larger chainring and sprocket, chances are your overall ratio remains the same.

    For example going from 30/15 to 40/20 retains the very same gear ratio and you won't feel a difference in the required effort to pedal the bike. (Larger rings do reduce stress on the chain, so they are better for drive train longevity.)

    When going from 26" to 29er, the rule of thumb is to add two teeth to the sprocket (rear).

  25. #25
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    Bigger cog in the rear = easier on hills, slower on flats.

    Think about it this way. With your 32 x 16, your rear wheel spins twice while your crank spins once. But if you have 32 x 32, your rear wheel spins once when your crank spins once. You are using the same amount of rotation to do half as much work. So it'll be easier to pedal on hills with bigger cog, but, since your rear wheel is spinning less per full crank rotation, you are slower on flats.
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