The past couple years have presented plenty of reasons to love the Alternator dropout, the versatile dropout system we started developing back in 2008 and first introduced at Sea Otter in 2010:
1. Versatility - The Alternator's adjustable swing plates allow the use of geared or singlespeed drivetrains on the same frame without chain tensioners or adaptors. It also means that when a hanger bends beyond repair, or a derailleur explodes, you can quickly and easily convert to a singlespeed drivetrain, and get yourself rolling back towards civilization (or home).
2. Easy - The bane of singlespeeds with track-end style dropouts is tedious wheel changes. With the Alternator's vertical-style dropout, it's a snap. There is no brake adaptor to loosen and no chain to re-tension. Just pop the wheel out, then back in, and go.
3. Slip Free - The swinging design and fixing bolts create a slip-free system using just one fixing bolt, compared to other systems which typically use two fixing bolts per side. The Alternator's lower fixing bolts are sized to do their job, and do it well. They do it so well that the set screws are not needed to prevent slipping. In fact, all the prototypes we tested did not even feature a set screw. We decided to add them to the final design to make chain tension adjustment super precise for the tweakers out there. Once adjusted and torqued, the set screws can be removed and the dropout will not slip under drivetrain or brake forces. Try it! It's another 5g lighter!
4. Variable Chainstay Length - Besides chain tensioning, the Alternator's swing plates also double as a geometry adjust. The 17mm of throw allow a direct variation in chainstay length and overall wheelbase. It doesn't sound like much, but just 5mm of chainstay length adjustment can make a huge difference in how a bike handles. This allows riders to fine tune the handling of the bike to their liking, or for the application at hand. Salsa's own Sean Mailen ran his Alternators in the rear-most position for the entire length of the Tour Divide route to maximize mud clearance and stability. On bikes like our Mukluk Ti, this adjustability also serves as a tire clearance adjustment, when every millimeter counts.
5. Minimal Maintainence - The Alternator holds fast and steady, and there are no surfaces that ever need to be cleaned or regreased. This means no creaking and no slipping.
6. Replaceable - All easily bendable or stripable features (like hangers and threads) are contained in the swing plates and hardware. Nothing crucial to function is part of the welded frame assembly. This means that if anything every does get tweaked of stripped, it's easily and readily replaced, and your frame is not rendered scrap metal.
Salsa design engineer Sean Mailen putting the Alternator dropouts to the test on the Great Divide Route...
7. Reliable - The Alternator has now completed several trips up and down the Tour Divide Route, a 2752-mile, off-pavement journey with nearly 200,000 feet of climbing that is notorious for exposing any and all weaknesses in bike frames and components. The Alternator has successfully completed this real-world torture test...and did it in both geared and singlespeed configurations.
For 2012, I'm happy to announce that we are also adding two very cool new reasons to be excited about the Alternator dropout:
8. 12 x 142 - Were adding a pair of plates compatible with a 12 x 142mm SRAM Maxle (which will be included). This will offer improved lateral stiffness, and open up the option to use the latest and greatest mountain bike hub and wheel offerings.
9. IGH - We're adding a left-side swing plate that uses the Rohloff OEM1 standard. Couple it with our singlespeed drive-side plate and let the IGH-enthusiasts rejoice!
Both of these new offerings have already been put through the paces and are currently in production. We expect to have them available July 1st, 2012.