12-30 cassette fitment

Discuss light weight issues concerning road bikes & parts.
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plpete
Posts: 520
Joined: Thu Dec 22, 2011 12:39 pm
Location: DC

by plpete

I'm slowly gearing up to ride my first Granfondo (Jeremiah Bishop's Alpine Loop) and I'd like to make any changes to my bike early on to avoid any issues during the ride. The ride will be about 100 miles and have about 11,000 feel of climbing, some of which will take place on compacted dirt roads and etc. Since I'm not a pure climber at 167lbs I'd like to adjust my gearing in order to handle the long and sometimes steep climbs for the ride. FYI I am running a Sram Force drivetrain with the new YAW Red front derailleur. The shifting is perfect. In the front I am running the Rotor Q Rings which I really like for climbing and will be sticking with those. They also help my knee pain. In the back I am running a Shimano 12-27 cassette. Although its fine for local hills, the long and steep at times climbs would be a bit easier with some taller gears on the top range. I know that officially the sram force RD will support up to a 28t sprocket. I have been eyeing the new Ultegra 12-30 cassette which seems like an ideal choice for the ride. The Apex 32t cassette will be a stretch but has anyone run the 12-30t cassette or the Tiagra equivalent on a Sram RD without going to a long cage Apex RD? Technically, the B screw on the RD could be adjusted to clear the RD pulley with the large cog. I've read of guys running the cassette with Ultegra RD which officially support up to a 27t cassettes. Any thoughts are appreciated :thumbup:

Valbrona
Posts: 1482
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

Don't worry, on the day you won't be the only one that didn't fit a triple.

by Weenie


HillRPete
Posts: 2292
Joined: Tue Apr 12, 2011 8:08 am
Location: Pedal Square

by HillRPete

I'm about to try a Tiagra 12-30 cassette on my training wheels (DA 7900 drivetrain). If you're hard pressed for clearance on the bottom gear seems to be to swap in a 10 tooth upper pulley.

eric
Posts: 2196
Joined: Tue Nov 11, 2003 9:47 pm
Location: Santa Cruz, California, USA
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by eric

A 7900 RD ought to clear a 30t cog. But in the end it depends on your frame's derailleur hanger.

I can get a 2012 Red RD to shift on to a 30t cog without even touching the B screw. But you have to try it on your bike to see if it works. If it doesn't and screwing the B screw in doesn't help, then you'll need a different derailleur.

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