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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 06-03-11, 11:23 PM   #1
Ritterview
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Gear-Calculator.com

I've been exploring gearing options, and came across this nifty gear selection tool, at Gear-Calculator.com.

Here I compare the 53-39 double with SRAM 11-36 10-speed cassette, as seen and discussed on this Paketa, with my setup, which is a 53-42-30 triple with Campy 12-29 11-speed.





This nicely visualizes and quantifies what you get with each setup. The 2X 11-36 has quite similar range, but not nearly the close spacing of the 3X 12-29.

I really appreciate this close spacing on the riding we do, for example, keeping up with fast single riders on rolling terrain on our club training ride. Making many small shifts while keeping optimum cadence allows us to mix in with the half-bikes, which in comparison to tandems have more variation in speed and rapid accelerations.

[The graphic was posted by doing a screen shot by pressing CTRL-PRINT SCREEN while on the site, and then PASTE in MS Paint, a Windows accessory program. The image is saved, and then uploaded to Flickr, or easier yet, Tiny Pic, which will provide the IMG code to past right into the post.]
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Old 06-04-11, 08:46 AM   #2
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It's not a bad graphic, but doesn't seem to support arbitrary gearing. Most important - doesn't support the most important feature, a quad chainring
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Old 06-04-11, 12:20 PM   #3
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I always used the Sheldon Brown calculator, but I like the graphical display this one has. Good find.

Here's mine: 56/42/30 with Sram XX 10s 11-32



30x32 is nice (I will most likely even switch back to the 28t chainring after RAAM). I am trying to get away from this habit of mashing I have gotten into the last year or so, and get back to higher cadence. Climbing at 90 rpm is 6.6 mph with the 30x32 or 6.2 mph with the 28x32.

Since I have been getting back to higher RPM climbing, my power is going up on longer efforts (10+ min).
http://app.strava.com/rides/666673#9929937 (my cadence here is mostly around 90 rpm, lower when standing)
*of course this example is my solo bike, and there are differences in preferable cadence between solo and tandem.

Last edited by uspspro; 06-04-11 at 12:31 PM.
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Old 06-04-11, 02:42 PM   #4
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I just use a spreadsheet with formulas that calculate the gear-inches. Easy to do, and easy to show several different gearing scenarios one above the other. Also easy to add formulas calculating speed at various cadences in the various gear combinations.
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Old 06-05-11, 12:07 AM   #5
Ritterview
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Quote:
Originally Posted by uspspro View Post
Here's mine: 56/42/30 with Sram XX 10s 11-32

...30x32 is nice I am trying to... get back to higher cadence. Climbing at 90 rpm is 6.6 mph with the 30x32
Here is a comparison then, at a leg-sparing 90 rpm cadence, between your Team JDRF-IGA and my clubride setups.

56/42/30 10s 11-32
52/42/30 11s 12-29



I hadn't seen that custom ring sizes were available, simply by moving the chainring/sprockets symbols. Neat.

It shows that we would need much lower gears to maintain a higher cadence. On 7.2% Tollhouse, our cadence was more in the 50-70 range, with a speed of only 3.6 mph.

As for the top end, if we get any over 30 mph my stoker wigs out, so no point in anything taller.

To get something like your RAAM setup, I would need to switch to a 28 tooth inner chainring, a 53 tooth outer chainring, and an 11-30 cassette. And then I'd have to make sure that the one-size RD cage could handle the additional chain wrap. That provided, they look similar now, though the 11th cog shows up three times to make the spacing tighter.

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Old 06-05-11, 11:48 PM   #6
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Quote:
Originally Posted by Ritterview View Post
It shows that we would need much lower gears to maintain a higher cadence. On 7.2% Tollhouse, our cadence was more in the 50-70 range, with a speed of only 3.6 mph.
I find climbing at 80-100 rpm makes more power (while seated), I like around 70's for standing. There are so many really steep hills around here that put us into that 50's rpm range, even with your typical tandem gearing, and it's just not efficient.

So I have no issues with running a 30x32 or 28x32.

My 32t cog is skipping on my XX cassette (I think it's the inbound limit screw or the aluminum big cog is just worn out), so I have been forced to use the 28t cog as my lowest gear (with 30t chainring, at the moment).. would have helped to have something lower on something like Metcalf (http://app.strava.com/rides/651634#9703410) after climbing Henry Coe at a solid pace earlier that day (http://app.strava.com/rides/651634#9703424).
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Old 06-07-11, 02:13 AM   #7
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Originally Posted by uspspro View Post
My 32t cog is skipping on my XX cassette (I think it's the inbound limit screw
Easy way to find out.
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