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  1. #1
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    Stupid questions about gears/cassettes. Sorry!

    OK, on my S3, I got a Di2 53/39 172 crank and on my P4 I got a Zipp Vumachronos 170 53/39. WTF do these numbers mean? I have no idea....Just took the advice of some bike pro.

    I got 7 Dura Ace 7900 cassettes: 11-21, 11-23, 11-25. A buddy told me I need a 28 for a hilly road race so I'm gonna get one of those. Why? No idea.

    I see that there are also available cassettes numbered 12-21, 12-23, etc.....

    What's the diff between the "11s" and the "12s??"

    How's an average shmoe like me supposed to decifer all these numbers???

    (scratches head with total befuddlement)

    Thanks again for your patience and input.

  2. #2
    Senior Member ericm979's Avatar
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    A 28 will turn you into a girl. Use the 11-21.

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    Quote Originally Posted by cyclisteaux View Post
    WTF do these numbers mean? I have no idea....Just took the advice of some bike pro.
    Hire me as your consultant. For a mere $100/hr ($200 minimum) I will explain it all to you... and more. We can even get into what tires and tubes to use.

  4. #4
    You blink and it's gone. rbart4506's Avatar
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    You have an S3 and a P4 and have no clue....Wow...

    It's early and I need a few secs to blow so here goes...

    172, 170 are the crank length...Thingy that your pedal screws in that you turn to make your bike go...

    11s, 12s....Number of teeth on the rear cassette...28 gives you a higher gear that makes it easier to spin going up hill...11 will allow you to go faster on the flats, assuming you can push the gear...

    Ride, train and read...
    "On the other hand riding down a hill at 55 MPH wearing (essentially) women's underwear and a Styrofoam cup on your head is the epitome of rational life-extending decisions." - RacerEx

  5. #5
    coffee-stained punk hammy56's Avatar
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  6. #6
    Senior Member KD5NRH's Avatar
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    Quote Originally Posted by rruff View Post
    Hire me as your consultant. For a mere $100/hr ($200 minimum) I will explain it all to you... and more. We can even get into what tires and tubes to use.
    For $150/hr ($600 minimum) I will tell you to pedal the damn thing and figure it out that way.

  7. #7
    powered by Racer Ex gsteinb's Avatar
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    Quote Originally Posted by rbart4506 View Post
    You have an S3 and a P4 and have no clue....Wow...
    + everything and the house

  8. #8
    Travelling hopefully chasm54's Avatar
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    I'm finding the OP rather hard to believe. Those bikes, SEVEN dura-ace cassettes, and he doesn't know what gears are? Nah.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

  9. #9
    powered by Racer Ex gsteinb's Avatar
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    NJ is filled with dentists who buy bikes in July.

  10. #10
    Ho-Jahm Hocam's Avatar
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    Suuuuuuuuuure

    Race-o-meter:
    Broken until next season

  11. #11
    Senior Member kevrider's Avatar
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    so you just do what he tells you to do, no questions. shouldn't you ask these things *before* you buy something? you can go to mfg websites (or pricepoint) and read up on your parts. or, perhaps, look closely at the parts.
    In a world full of people, only some want to ride. Isn't that crazy?
    Seal/CRAZY/misquoted

  12. #12
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    Sorry, not a troll or DDS. I'm just not a technical guy and a little intimidated with anything mechanical so I pay a professional to work on my bike. Slowly trying to do things myself but unfortunately this sometimes backfires on me. For instance, I travelled with my bike and had to reassemble it. Tried making experimental adjustments to the rear derailleur (Those tiny screws). Day before a race, in a test run, the chain derails behind the cassette and gets jammed!

    Had to hitch-hike to a bikeshop and pay a mechanic to fix it.

    Makes sense to learn about all this stuff, hence, my stupid questions. Too embarrassed to ask my cycling buddies. ;-)

    How does a 12-23 compare with an 11-23? What does the 11/12 refer too?

  13. #13
    Travelling hopefully chasm54's Avatar
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    Quote Originally Posted by cyclisteaux View Post



    How does a 12-23 compare with an 11-23? What does the 11/12 refer too?
    See rbart4506 post above.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

  14. #14
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    Thx. I saw that, but when would one use a "12?"

    Quote Originally Posted by chasm54 View Post
    See rbart4506 post above.

  15. #15
    Senior Member ericm979's Avatar
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    Quote Originally Posted by rbart4506 View Post
    28 gives you a higher gear that makes it easier to spin going up hill.
    That's a lower gear, not higher. 39x25 is a 1.56:1 gear ratio (rear wheel turns 1.56 times for every crank revolution). 39x28 is 1.39:1. 1.39 is lower than 1.56, hence it is a lower gear ratio.

  16. #16
    Senior Member ericm979's Avatar
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    Quote Originally Posted by cyclisteaux View Post
    Thx. I saw that, but when would one use a "12?"
    when you don't need an 11.
    a 11-25 has 11,12,13,14,15,17,19,21,23,25
    a 12-25 has 12,13,14,15,16,17,19,21,23,25

    That 16t cog that's on the 12-25 is awfully handy. The 11-25 has a large gap from the 15 to the 17. So if you're riding at a speed where the 16t cog would be ideal, you have to either turn the pedals faster on the 17t, or slower on the 15t. If you don't use the 11t then using a 12-xx cassette would avoid this problem.

  17. #17
    Travelling hopefully chasm54's Avatar
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    Quote Originally Posted by cyclisteaux View Post
    Thx. I saw that, but when would one use a "12?"
    The more teeth on the rear sprocket the lower the gear, therefore the easier to push. So a 12 sprocket is almost 10% lower/easier than an 11, and so on. People use a cassette with a 12 as its lowest gear if they find they rarely go fast enough to need the 11, or want a bigger sprocket at the top end for climbing, without sacrificing the close ratios implied by moving up in small steps. Personally I can't be bothered swapping cassettes/ wheels all the time, and there's a lot of severe climbs round here, so I usually run a 12-27. I don't race, so don't really need the 11 for sprinting (I can barely sprint out of sight on a dark night anyway LOL) and having the 27 means I can climb virtually anything. The price I pay is a more substantial step up between gears - the cassette goes 12, 13, 14, 15, 17, 19, 21, 23, 25, 27.

    I'm giving you the benefit of the doubt here, but I still can't really believe that anyone who claims to race bikes doesn't know this stuff.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

  18. #18
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    OK, thx for the info, guys.

    And yes, I'm a troll that has nothing better to do than to make believe I'm a new bike racer asking detailed questions on gearing.

  19. #19
    Senior Member ericm979's Avatar
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    Quote Originally Posted by chasm54 View Post
    People use a cassette with a 12 as its lowest gear if they find they rarely go fast enough to need the 11,
    Highest.

  20. #20
    Senior Member KD5NRH's Avatar
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    Quote Originally Posted by ericm979 View Post
    when you don't need an 11.
    a 11-25 has 11,12,13,14,15,17,19,21,23,25
    a 12-25 has 12,13,14,15,16,17,19,21,23,25

    That 16t cog that's on the 12-25 is awfully handy. The 11-25 has a large gap from the 15 to the 17. So if you're riding at a speed where the 16t cog would be ideal, you have to either turn the pedals faster on the 17t, or slower on the 15t. If you don't use the 11t then using a 12-xx cassette would avoid this problem.
    But what if i'm riding at a speed where 18 would be ideal? Can't they wedge four more cogs in there so I never have to face that problem?

  21. #21
    fuggitivo solitario
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    Quote Originally Posted by hammy56 View Post
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    too many POS threads here

  22. #22
    Senior Member withsriracha's Avatar
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    I just can't get past the SEVEN cassettes....
    "So, is 'aero' cyclist-speak for 'good'?" -My (noncyclist) best friend

  23. #23
    going roundy round wanders's Avatar
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    Quote Originally Posted by ericm979 View Post
    A 28 will turn you into a girl. Use the 11-21.
    Jens Voigt's cassette goes 11-11-11-11-11-11-11-11-11-12 (for the hills).

    Jens Voigt's cranks have 2 chainrings, a 56 and a 56.
    Quote Originally Posted by CastIron View Post
    Damn.

  24. #24
    Senior Member Homebrew01's Avatar
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    Quote Originally Posted by cyclisteaux View Post
    And yes, I'm a troll that has nothing better to do than to make believe I'm a new bike racer asking detailed questions on gearing.
    Wouldn't be the first time.

    http://coachlevi.com/cycling/complet...ears-shifting/
    Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike

  25. #25
    ride lots be safe Creakyknees's Avatar
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    Quote Originally Posted by cyclisteaux View Post
    OK, on my S3, I got a Di2 53/39 172 crank and on my P4 I got a Zipp Vumachronos 170 53/39. WTF do these numbers mean? I have no idea....Just took the advice of some bike pro.

    I got 7 Dura Ace 7900 cassettes: 11-21, 11-23, 11-25. A buddy told me I need a 28 for a hilly road race so I'm gonna get one of those. Why? No idea.

    I see that there are also available cassettes numbered 12-21, 12-23, etc.....

    What's the diff between the "11s" and the "12s??"

    How's an average shmoe like me supposed to decifer all these numbers???

    (scratches head with total befuddlement)

    Thanks again for your patience and input.
    Allow me to introduce you to the late, great Sheldon Brown. Read and learn.

    http://www.sheldonbrown.com/gearing/index.html
    "have fun and be kind"
    - an internet post

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