Gearing issue question.......

Discussion in 'Road Bikes' started by Frankie, Feb 19, 2011.

  1. Frankie

    Frankie New Member

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    I ride a TREK 2.3 bike right now. I am looking to buy another bike soon and this is my question. I have been rolling along rather well with my triple crankset. My TREK has a 50/39/30 on her now with a 11-28 10 speed rear cassette. The bikes I am looking at now....TREK and GIANT in an up-graded model offer a 50/34 crank and a 11-28 cassette on the ( TREK) and 39/53 crank and a 12x25 10 speed on the (GIANT). I find this very complicated as I can't say I really understand the whole crank/cassette ratio thing. Any help would be greatly appreciated. From my reading up on this subjet, looks like the compact is the way to go, I think. :confused:
     
  2. Industry_Hack

    Industry_Hack Total noob (& forum admin) Admin Staff Tavern Member

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    Frankie, I'll make this really simple for you. If you use Sheldon Brown's Gear Calculator for your current ride and then plug in the numbers for your prospective purchase, you'll be able to compare gear inches quite easily. What you're looking for is the same figures from both sets of gears. As long as you still have roughly the same gear inches for your climbing, sprinting, and cruising, you should be fine.
     

  3. Frankie

    Frankie New Member

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    Awesome, that is what I was looking for! I will add the numbers and see what happens. Thanks
     
  4. Industry_Hack

    Industry_Hack Total noob (& forum admin) Admin Staff Tavern Member

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    You're not likely to run out of top end, so you just need to make sure you still have a good climbing gear if you ride in hilly areas.
     
  5. Frankie

    Frankie New Member

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    Well, I live and ride in East Tennessee so that means lots, lots, lots of climbing. I am really not a speedy rider so running out of gear would be hard to do, but I do enjoy climbing and low gears when I need them. This TREK is my first road bike and I must admit, the triple comes in handy sometimes.
     
  6. jeepster93

    jeepster93 New Member

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    50/34 and 12/25 is fairly standard for road gearing.

    I think this is another spot where the bike makers drop the ball. There is no way I am going to spin a 53/10 gear. This would be 40-45 mph. I don't see myself doing that on a 17 pound bike, even down hill.

    The 10 speed rear cluster will help a lot with the hills, a couple of those rear gears are fairly large, I call the last 2 my granny gears.

    I got a road bike equipped with a smaller front crank. I got a 43/30. This is a cyclocross crank. I need to climb hills(I live in Colorado) and the smaller crank is a major upgrade for this.
     
    Last edited: Feb 20, 2011
  7. flanderscycling

    flanderscycling New Member

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    So, stay with the triple!
     
  8. rola643

    rola643 Two skinny Js Staff Member Admin Staff Mod Team Tavern Member

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    I'm going out to Asheville,NC this summer to see my son and hoping that a compact will be ok. If I use my compact in this area it's almost always on the big chain ring. A double works better for me being a flatlander.

    I think I would have to consider staying with a tripple out there. They seem very finicky on the front derailleur adjustments tho.
     
  9. Frankie

    Frankie New Member

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    Thanks for the advise guys. Only problem with sticking with a triple is this: In the model I want from TREK or GIANT, neither offers a triple on the crankset. Like I have said, I don't have a problem with my triple, even if I have taken a little ribbing over it from some better riders ( who of course are strong enough for a compact ) I could purchase the bike and then add a different cassette or even maybe a crankset ( triple ), but that would to be adding to the cost of the bike. I hate to be a whinner, but without asking I will never know. Most people on this forum have already forgot more about biking than I will ever know. I would like to have something worked out before the May 7th. 3 mountain, 3 state ride down in Chattanooga Tennessee.
     
  10. jad3

    jad3 Helmet up, wheels down.

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    Like Hack said it comes down to the ratios -

    Here is the 53/39 -11/28 I ride
    Front Rear Wheel Gear Inch Ratio
    39 28 700 37.61 1.39
    39 25 700 42.12 1.56
    39 23 700 45.78 1.70
    39 21 700 50.14 1.86
    39 19 700 55.42 2.05
    53 25 700 57.24 2.12
    39 17 700 61.94 2.29
    53 23 700 62.22 2.30
    53 21 700 68.14 2.52
    39 15 700 70.20 2.60
    39 14 700 75.21 2.79
    53 19 700 75.32 2.79
    39 13 700 81.00 3.00
    53 17 700 84.18 3.12
    39 12 700 87.75 3.25
    53 15 700 95.40 3.53
    53 14 700 102.21 3.79
    53 13 700 110.08 4.08
    53 12 700 119.25 4.42
    53 11 700 130.09 4.82


    It takes me to a "Tall End" ratio of 4.82 which is more than I need unless I am going down a pretty steep hill and a Short of 1.39 which I can take up to 18-20% climbs pretty well (though not forever sadly and my HR spikes seriously:))

    Comparing your compact scenario - 50/34 - 11/28
    Tall: 4.55
    Short: 1.21

    And the triple - 50/39/30 - 11/28
    Tall: 4.55
    Short: 1.07

    Not sure if all this helps but it can give you an idea of the relative ratios...and you can compare your current gearset to understand what it would feel like to lose some of your climbing gears. Basically the compact would take away 1 gear off your climbing so try your ride on your triple without the super granny (granny chain ring with biggest sprocket). Instead stay one down on your cassette (the one in the back).

    If you want to see what you could do on a 53/39 - you can just stay out of your granny (smallest front chainring) :)

    I put the calculated ratios below - Anyone everyone please correct my logic/math - thanks

    Triple:
    Front Rear Wheel Gear Inch Ratio
    30 28 700 28.93 1.07
    30 25 700 32.40 1.20
    30 23 700 35.22 1.30
    39 28 700 37.61 1.39
    30 21 700 38.57 1.43
    39 25 700 42.12 1.56
    30 19 700 42.63 1.58
    39 23 700 45.78 1.70
    30 17 700 47.65 1.76
    39 21 700 50.14 1.86
    30 15 700 54.00 2.00
    50 25 700 54.00 2.00
    39 19 700 55.42 2.05
    30 14 700 57.86 2.14
    50 23 700 58.70 2.17
    39 17 700 61.94 2.29
    30 13 700 2.31
    50 21 700 64.29 2.38
    30 12 700 67.50 2.50
    39 15 700 70.20 2.60
    50 19 700 71.05 2.63
    39 14 700 75.21 2.79
    50 17 700 79.41 2.94
    39 13 700 81.00 3.00
    39 12 700 87.75 3.25
    50 15 700 90.00 3.33
    39 11 700 95.73 3.55
    50 14 700 96.43 3.57
    50 13 700 103.85 3.85
    50 12 700 112.50 4.17
    50 11 700 122.73 4.55


    Compact:
    Front Rear Wheel Gear Inch Ratio
    34 28 700 32.79 1.21
    34 25 700 36.72 1.36
    34 23 700 39.91 1.48
    34 21 700 43.71 1.62
    34 19 700 48.32 1.79
    34 17 700 54.00 2.00
    50 25 700 54.00 2.00
    50 23 700 58.70 2.17
    34 15 700 61.20 2.27
    50 21 700 64.29 2.38
    34 14 700 65.57 2.43
    34 13 700 70.62 2.62
    50 19 700 71.05 2.63
    34 12 700 76.50 2.83
    50 17 700 79.41 2.94
    50 15 700 90.00 3.33
    50 14 700 96.43 3.57
    50 13 700 103.85 3.85
    50 12 700 112.50 4.17
    50 11 700 122.73 4.55
     
  11. Frankie

    Frankie New Member

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    Thanks for the help! Heck, if I am only going to give up my lowest gear, I can handle that for sure. Getting a compact don't sound to bad.
     
  12. jad3

    jad3 Helmet up, wheels down.

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    Yeah - you lose some granularity in there too...

    Maybe try renting a compact double and see what you think on one of your favorites rides?
     
  13. Frankie

    Frankie New Member

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    Very good idea, I have never tried a compact yet. That is something I will do and most LBS will work with you if they feel it will get them a sale. Awesome suggestion!!
     
  14. chibibike

    chibibike Banned

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    so i can put in different gears so i can go faster? something better for speed? I wanna do that. My gears are whatever came stock with the trek utopia. what would i need if i wanna go 25-40 MPH on the road? I'm all for it if it'll make it faster or at least easier to petal.
     
  15. Xela

    Xela New Member Tavern Member

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    Chibibike, what gears do you have on there now? Your top speed will be determined by the number of teeth on your big chainring in the front and the number of teeth on the smallest gear on the back. For a bike such as yours, getting a little more speed might be easier obtained by swapping your cassette on the rear. Depending on the cassette (cluster of gears in the back), you can sometimes sway individual gears instead of changing the whole cassette.

    If you're bike's still fairly new, the shop you bought it from might be willing to work with you on this at little or no charge. When I bought my first roadbike, they told me to try out the stock gears, but they anticipated I might want something easier for the hills around here. After a few rides, I realized they were right and they swapped my cassette free of charge.
     
  16. chibibike

    chibibike Banned

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    I just found the specs for it online.

    Crank Shimano M431, 48/36/26
    Cassette SRAM PG-950 11-32, 9 speed

    so is there a better one I can get?
     
  17. Weav

    Weav GiddyUp

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    Frankie, have you looked into SRAM Apex groupset. This is dubbed the tripple killer. It is a double chainring with an 11-28 rear or an 11-32 for the mountains. The idea is that it is lighter than a triple by eliminating one chainring from the triple. It is the least expensive offering in the SRAM lineup and I'd wager any decent shop would be willing to swap it out for you at no or minimal cost.
     
  18. chibibike

    chibibike Banned

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    can i put a 10 speed cassette on if the one that came with it is a 9 speed? what's the difference?
     
  19. chibibike

    chibibike Banned

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    Weav, that's a nice looking bike.
     
  20. Xela

    Xela New Member Tavern Member

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    A 48/11 is pretty big for a MTB. I wouldn't change that if you are generally happy with it. That ratio should theoretically allow you to go 30 mph with a pedal cadence of 90 rpm. 10 and 9 speed are usually not compatible.