SHIMANO DERAILLEURS - FRONT
Shimano Dura-Ace FD-7900 Front Derailleur
- Item: SHI0149 Actual Weight:"Actual Weight" means we weighed this item ourselves. 66 g
LOL. There, we said it -- the first time ever on the Competitive Cyclist website. LOL. Why are we LOL-ing? Because we know that's exactly what the mad engineers at Shimano are doing about the Dura-Ace FD-7900 front derailleur.
It's just a front derailleur -- what can be so amusing? It's this: When Shimano's arch-nemesis SRAM unveiled their much-ballyhooed Red component group in fall 2007, one of its most-hyped attributes was the fact that the left Red Doubletap lever (in contrast to SRAM Force and Rival) allows for front derailleur trimming. It has a micro-shift to it, which allows you to cross chain in gears like a 53x21 and eliminate noisy front derailleur/chain rub. And this was a fine enhancement, so long as you didn't dig too deep into the details (e.g. Red doesn't allow for trimming when you're in the small chainring -- so you're SOL if you're in a 39x13. Cross-chaining in the small ring is noisy as hell. Another fact, of course, is that Shimano has offered front derailleur trim in the STI lever since, like, forever).
What's funny (or at least interesting) is this: The great innovation with the Dura-Ace FD-7900 is that Shimano has eliminated the need for front derailleur trimming. SRAM hasn't yet figured out how to provide it, and suddenly Shimano has made the need (in a Dura-Ace drivetrain, anyway) obsolete. Thanks to the fresh design of both its cage profile and the linkage, you can cross-chain to your heart's content. You won't get chain rub, so you won't need to micro-shift the noise away. Sure, 53x25 and 39x11, etc. are usually unwise gears to be in -- they put excessive wear on your drivetrain, and they have loads of mechanical drag. But, then again, at crunch time on race day, your pain-addled, oxygen-starved brain isn't optimally situated for thoughtful shifting decisions.
The redesigned and widened linkage combined with the optimized spring tension reduces the shifting force required to move between chainrings. These shifts typically happen under a decent bit of load -- exactly the situation Shimano had in mind with the Dura-Ace FD-7900. Many folks say the most dramatic shifting improvements between 7800 and 7900 are with the front derailleur, not the rear.
The Shimano Dura-Ace FD-7900 front derailleur is available in braze-on, 28.6mm clamp, 31.8mm clamp, and 34.9mm clamp. It is compatible with the Shimano Dura-Ace FC-7900 and FC-7950 cranksets and Shimano Dura-Ace CN-7900 chain. According to Shimano it is not compatible with the Dura-Ace 7800 series crankset and chain.