# chain ring sizes for a road tandem



## Wax (Nov 9, 2005)

yes I know it's MTBR, who cares, I'm a mountain biker who just got a tandem! 
Since that's out of the way on to my question.

my tandem is a Burely Duet and she's a beaut. the problem is myself and the stoker are both fairly strong riders and we are spinning out in the tallest gear we have! Currently the big chainring is a 52 tooth, I'm not sure the span of the cassette (7 speed) I think the smallest cog is 13 or something.

The question is, are we better off putting on a bigger chainring (54, 56, +), a smaller cassette (down to 11), or just pedaling like a bat out of hell since the bike is performing flawlessly at the moment and I'm scared to screw it up?

Thanks for anyone's help!


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## DaleTR (Apr 6, 2007)

*Both*

Years ago, my ex and I were road racing, and regularly borrowed a road tandem. It was REAL easy for 2 strong riders to spin out a 54x12 on the flats.....

I would get at least a 53x12 top gear. That would get you a 119.25 inch gear, compared to a 108 inch gear for the existing 52x13. Gives you almost 10% higher gear, with minimal gear changes. 12 tooth 7 speed cogsets are common, and should have NO effect on the rear shifting. The 1 tooth change in the front should also have miniimal impact on the shifting, and most deraillurs should have the capacity to deal with the change.

Good Luck & go fast. (Oh, and once you get bored with the road tandem, get an Ellsworth Witness...... More fun han should be legal  ).


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## Wax (Nov 9, 2005)

thanks DaleTR for the help!
turns out the tandem has a freewheel instead of a cassette, this means the smallest rear cog available is a 13 tooth model. I could update the rear hib to a freehub body, but that's a lot of work. the bike has a drum brake on it which would complicate an upgrade a little bit. 

so I guess I'm back to considering a new chainring.
what's the equation for calculating gear inches?
I want to figure out what a 54 or even a 56 tooth chaniring would do to the final drive.

about the mountain tandem.... I'm an east coaster, most of the trail out here is really tight and I'm not sure I could even push a tandem through the majority of it!


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## DaleTR (Apr 6, 2007)

*gear INches*

Front teeth / Rear teeth * 27 (Wheel circum) = gear inches

Or an online gear calculator (from Sheldon Brown...)
http://www.sheldonbrown.com/gears/

And it does seem hard to find a 7 speed, 12T FREEWHEEL.... makes it harder. With a 13 in the back, even a 57T chainring does not quite get up to the gear inches of a 53x12. Going that big will very likely give you fits on front shifting, and may exceed dérailleur capacity. Maybe pedaling faster IS the right answer


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## tductape (Mar 31, 2008)

Not familiar with the Duet (Wheelsize, crankarm size? ). Updated my old Rodriguez with 26" wheels to 9 speed cassette. We still run out of gears with at 52/11. Switching soon to a 54/11.


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## Wax (Nov 9, 2005)

thanks for everyones help.


in the event that I ever trash the rear wheel or hub I'll upgrade it to a freehub body and put on a cassette with an 11 tooth cog. I think for now we'll just pedal faster and coast more!


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