Bike Forums - View Single Post - Compact Double versus Triple

01-25-10 | 01:46 PM

#46

HiYoSilver

Rides again

Joined: Oct 2004

Posts: 3,282

Likes: 1

From: SW. Sacramento Region, aka, down river

Bikes: Giant OCR T, Trek SC

Quote:

Originally Posted by BlazingPedals

Adding a SRAM DualDrive to your existing drive train will give you a 0.73 underdrive and a 1.36 overdrive, while preserving all your current gears. It triples the effective number of chainrings you have. You have to be willing to put a third shifter on your handlebars, though.
http://www.prowheelbuilder.com/product.php?prod_id=332
(That's not to endorse the dealer, only to show the product.)

Interesting. It is another 2.6lbs/42 oz. I don't quite understand what underdrive and overdrive would do. How does that change the gear ratio or GI? 3 lbs, quite a bit of extra weight.

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