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  1. #1
    Tandem Vincitur Ritterview's Avatar
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    Gear ratios, obtaining range from chainrings vs. cassette.

    I had been running 52-39-28 on our Campy Athena 11-speed triple (Lightning crank) with the largest Campy cassette, 12-29.

    But with the advent 11-speed Shimano and SRAM, Campy and Shimano cassettes are interchangeable. So, we changed the freewheel on our DT Swiss hubs from Campy to Shimano, and put on a Shimano Ultegra 11-32 cassette.

    With the range coming from the cassette, this allowed reverting to Athena spec 52-39-30 chainrings (Ultegra triple). Now the Athena FD shifts fine (since we added the FSA tandem FD clamp).

    We've done some of the steep climbs with which our terrain abounds, and both us agree that the 30t granny 32t cassette seems soooo much easier than the 28t granny 29t cassette.

    But when I made the graphic in Gear-Calculator, they hardly vary in ratio. For 11-32 (top) and 12-29 (bottom), the ratio is 0.94 and 0.97 respectively.




    Can we really notice a ratio improvement of 0.03? Or are we just fooling ourselves?

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    Quote Originally Posted by Ritterview View Post
    I had been running 52-39-28 on our Campy Athena 11-speed triple (Lightning crank) with the largest Campy cassette, 12-29.

    But with the advent 11-speed Shimano and SRAM, Campy and Shimano cassettes are interchangeable. So, we changed the freewheel on our DT Swiss hubs from Campy to Shimano, and put on a Shimano Ultegra 11-32 cassette.

    With the range coming from the cassette, this allowed reverting to Athena spec 52-39-30 chainrings (Ultegra triple). Now the Athena FD shifts fine (since we added the FSA tandem FD clamp).

    We've done some of the steep climbs with which our terrain abounds, and both us agree that the 30t granny 32t cassette seems soooo much easier than the 28t granny 29t cassette.

    But when I made the graphic in Gear-Calculator, they hardly vary in ratio. For 11-32 (top) and 12-29 (bottom), the ratio is 0.94 and 0.97 respectively.




    Can we really notice a ratio improvement of 0.03? Or are we just fooling ourselves?
    What's the difference in chain inches?

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    You're fooling yourselves.

  4. #4
    Tandem Vincitur Ritterview's Avatar
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    Quote Originally Posted by Bad1 View Post
    What's the difference in chain inches?
    You mean, how many links in the chain? I don't know, we got a new chain but I wasn't sure how many links were in the old and new.

    At the link, there is a dropdown at which the units can be changed from among ratio, development, speed and teeth.

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    Quote Originally Posted by Ritterview View Post
    You mean, how many links in the chain? I don't know, we got a new chain but I wasn't sure how many links were in the old and new.

    At the link, there is a dropdown at which the units can be changed from among ratio, development, speed and teeth.
    I need to rephrase gear inches

  6. #6
    Senior Member waynesulak's Avatar
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    Quote Originally Posted by Ritterview View Post
    I had been running 52-39-28 on our Campy Athena 11-speed triple (Lightning crank) with the largest Campy cassette, 12-29.

    But with the advent 11-speed Shimano and SRAM, Campy and Shimano cassettes are interchangeable. So, we changed the freewheel on our DT Swiss hubs from Campy to Shimano, and put on a Shimano Ultegra 11-32 cassette.

    With the range coming from the cassette, this allowed reverting to Athena spec 52-39-30 chainrings (Ultegra triple). Now the Athena FD shifts fine (since we added the FSA tandem FD clamp).

    We've done some of the steep climbs with which our terrain abounds, and both us agree that the 30t granny 32t cassette seems soooo much easier than the 28t granny 29t cassette.

    But when I made the graphic in Gear-Calculator, they hardly vary in ratio. For 11-32 (top) and 12-29 (bottom), the ratio is 0.94 and 0.97 respectively.




    Can we really notice a ratio improvement of 0.03? Or are we just fooling ourselves?
    I think that is big enough to feel. Some of the gear changes on a 12-25 cassette are about 6%. You probably do have a placebo effect working too but if you were having to struggle to stay on top of the higher gear and keep your cadence in your comfort range, then that little difference would be a bigger deal.

  7. #7
    Rod & Judy gracehowler's Avatar
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    I agree, think you need more like 3% to tell a big difference.
    R&J

  8. #8
    Tandem Vincitur Ritterview's Avatar
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    Quote Originally Posted by Bad1 View Post
    I need to rephrase gear inches
    As you can see, Gear Inches is indicated on the top line. On the dropdown it is I think called Development. The 32t is 25 and the 29t is 25.8

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    At your set cadence, your table shows a difference of about 0.25 mph (6.25mph @ 32T vs. 6.5mph @ 29T). On a long steep climb, you may sense that difference in speed.
    This answer brought to you by an old steel old single speed rider without a computer on the bike. FWIW
    Oh yeah. And a tandem (not SS though).
    LouM...

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    So if you were climbing at 80rpm now at the same speed you will be at around 82rpm. It certainly wouldn't make any difference to me but maybe some others are more finely tuned to such small changes.
    When I ride my fixie cadence often ranges from 30-200rpm. Definitely lose power at the extremes but from 60-120rpm I don't think I am giving up much to the geared bikes at all.

  11. #11
    just another gosling Carbonfiberboy's Avatar
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    All other things being equal, you get less chain tension from a larger ring and thus longer drivetrain life. So it's all good.

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    riding the 30/32 arrangement would be similar to riding a 28/30 (something closer to 28/29.87) or conversely the 28/29 would be similar to a 30/31. Don't know about it being "sooooo" much easier, but very possibly noticeable. My guess is you climbed your hills about 3% slower with the new set up??? Or, at the same speed your cadence increased by 3%.

    Plus, and this is only speculation, but it seems that, on timing rings anyway, larger rings seem to produce less "drag" (lack of a better term) than smaller rings. Please correct if this idea is somewhere between crazy and dillusional.

    Edit: 2.9%

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    I see three possible factors:
    1. 3% should be noticeable.
    2. Larger ring/cog on the new set-up should lead to a small reduction in chain friction that might not be noticeable but for the 3%.
    3. It should be both cleaner shifting and a smaller jump to drop from your middle ring to your new small chain ring. This may allow you to keep more momentum as the hill picks up, which shortens the hill.

  14. #14
    Tandem Vincitur Ritterview's Avatar
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    Thanks for the comments.

    I think that our impression is 20% gear improvement and 80% hopeful expectation.

    Here's a few pics of the new setup.






    The Shimano Ultegra chainrings are great, and look right. An old 30t TA inner chainring is retained.



    The FSA tandem FD clamp puts the FD outward an extra 5 mm, which brings the Athena FD out from the 43.7 mm chainline it is expecting to work the 48 mm Lightning chainline. The Athena now works and looks better than the Shimano DA FD we heretofore had to use.

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    I have recently heard that "any day one wakes up on the green side of the grass is a good day". Me worry about 0.03? No, not gonna do that.

    /k

  16. #16
    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by gracehowler View Post
    I agree, think you need more like 3% to tell a big difference.
    R&J
    Am I missing something here?

    However you slice it, the difference between the 2 gears, is a bit over 3%. In gear inches, the difference between 25 and 25.8 is 3.1%

    In development factor, the difference between .94 and .97 is 3.1%

    And in speed the difference the difference between 6.25mph and 6.5mph is 4%. Given that these should all be 3.1%, my bet is the speed difference is actually slightly less than .25 mph

    And if you're climbing at 6.25 mph, you can definitely feel the extra effort it takes to go to 6.5mph
    You could fall off a cliff and die.
    You could get lost and die.
    You could hit a tree and die.
    OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.

  17. #17
    Senior Member waynesulak's Avatar
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    Quote Originally Posted by merlinextraligh View Post
    Am I missing something here?

    However you slice it, the difference between the 2 gears, is a bit over 3%. In gear inches, the difference between 25 and 25.8 is 3.1%

    In development factor, the difference between .94 and .97 is 3.1%

    And in speed the difference the difference between 6.25mph and 6.5mph is 4%. Given that these should all be 3.1%, my bet is the speed difference is actually slightly less than .25 mph

    And if you're climbing at 6.25 mph, you can definitely feel the extra effort it takes to go to 6.5mph
    Well said

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    I am always intimidated to respond on this forum because there is so much knowledge here. However could the difference in step % make the shift from the 28t to the 32t feel more significant than the 26t to the 29t. Along with the other factors mentioned, I think that could be a factor.

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    30x32 is the magic ratio for my stoker and I to climb up 16-19% grades. While I like closer spacing of the Sram 11-28 10 speed cassette, 30x28 just isn't low enough for us going up the steeper hills in Silicon Valley compared to the XTR 10 speed 11-32.

  20. #20
    pan y agua merlinextraligh's Avatar
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    ^ We prefer a tighter spaced cassette, and a smaller inner chainring. Our setup for the mountains is 53/39/26, with an 11-28 cassette.

    The 26/28 is the slightest bit lower than 30/32, and you have closer ratios for most of the range with the 11-28.

    The shift between the 26/39 may not be as good as between 30/39, but we're not goining in and out of the 26 often, so we'll take that tradeoff for a more tightly spaced cassette.
    You could fall off a cliff and die.
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    You could hit a tree and die.
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  21. #21
    Tandem Vincitur Ritterview's Avatar
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    Quote Originally Posted by merlinextraligh View Post
    The shift between the 26/39 may not be as good as between 30/39, but we're not goining in and out of the 26 often, so we'll take that tradeoff for a more tightly spaced cassette.
    Yeah, the thing for us is just a casual Sunday ride around town is mountainous, with nearly 1000 ft of climbing for each 10 miles. We visit ol' granny a lot. Can't go searching for it, we need it bad and often.



  22. #22
    just another gosling Carbonfiberboy's Avatar
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    Our chainrings are similar to Merlin's. We also have a lot of hills we have to granny. The drop to 26 is no problem as long as our 39 is not burred. Getting it back to 39, we wind it up, ease off and shift. It won't go either way under full power, but I doubt the 30 is any different. I was lucky enough to secure what are probably the last NOS SS 26T rings. We burr the heck out of aluminum grannies in no time. Chainsuck.

    I've gone to the same rings on my aluminum climbing bike with a 12-25 cassette, and for the same reason.

  23. #23
    Senior Member Team Fab's Avatar
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    Quote Originally Posted by ambient View Post
    I am always intimidated to respond on this forum because there is so much knowledge here. However could the difference in step % make the shift from the 28t to the 32t feel more significant than the 26t to the 29t. Along with the other factors mentioned, I think that could be a factor.
    Don't worry people like me post stupid stuff all the time.

    But I do think you are on to something. If the step to the gear is larger it may alter how you feel it.

    Definitely a factor to how it feels.

  24. #24
    Senior Member waynesulak's Avatar
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    Quote Originally Posted by Ritterview View Post
    Yeah, the thing for us is just a casual Sunday ride around town is mountainous, with nearly 1000 ft of climbing for each 10 miles. We visit ol' granny a lot. Can't go searching for it, we need it bad and often.


    The solution to the granny problem may be to use a 110 crank rather than the 130. This allows for a middle ring that better centered between the middle between the big and small rings. For me something like the following shifts fine with a 10 Speed Ultegra FD and Campy Shifters.

    Big ring 52 up 16 teeth but 140% of middle ring.
    middle ring 36 up 10 teeth from granny but 140% of smaller ring
    Little ring 26

    The above evens out the amount you have to move the chain with the FD between rings.

    Highest gear 52/11 or 4.72
    Lowest gear 26/28 or 0.929

    Also gives a good middle ring low gear 36/28 or 1.285 to help minimize the granny ring usage on moderate grades.

    The rear has reasonable steps on the rear cassette. We run a 12-28 cassette to make it a little closer and 24/36/50 rings make it a little lower. Not having a lot of power does focus the mind on gearing options.
    Last edited by waynesulak; 03-31-14 at 02:51 PM.

  25. #25
    Senior Member joe@vwvortex's Avatar
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    Quote Originally Posted by merlinextraligh View Post
    ^ We prefer a tighter spaced cassette, and a smaller inner chainring. Our setup for the mountains is 53/39/26, with an 11-28 cassette.
    Same here. I run the same in the front 53/39/26 but since I'm Campy 10spd with a Veloce 12-30 cassette. It's near perfect for us. Nice tight spacing in the cassette and the granny can get us up anything we dare ride. I even don't really miss the 11 that we used to have when I made a custom 11-29 cassette previously.
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