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Welcome to In The Stand, a how-to series that forces you to sit through a history lesson before you learn anything important. In this installment, I pull a 2007 Yeti 575 off the hook for a derailleur adjustment. But what was the 2008 Yeti 575? The Colorado brand was still making aluminum bikes at the time, but carbon fiber was evolving. We knew it could be structured in a way that allowed it to flex. Cannondale proved it years earlier with the first Scalpel, a carbon/aluminum hybrid cross-country bike that used carbon chainstays to achieve the necessary flex to allow its linkage to move. But if you ever get your hands on one (which we may in a future episode), you’ll notice how much flex there were in those stays. The answer was to localize the flex, something that bikes like the Specialized Stumpjumper, Kona Hei Hei and current generation Cannondale Scalpel have achieved. Yeti took an interesting approach, with two solid forged carbon inserts bonded into the seatstays just above the dropouts on the 575, a pretty aggressive bike for such a system. But they had good reason. Weight at the dropout is unspring, meaning it’s taking ground impacts with no help from the suspension. Removing unsprung weight literally helps the suspension work better. Also, these pivots aren’t like the rest. They don’t move much, which is why many brands gave up on ball bearings altogether and use bushings instead.
Unfortunately, the flex inserts in the 575 would occasionally come unbonded from the aluminum frame, and the idea was eventually scrapped. But this frame survived long enough to come into the shop for a derailleur adjustment on its Shimano Xt derailleur, model M750. This was not just any XT derailleur. This generation marked the change from 8- to 9-speed, and it ruffled some feathers. When we went from 7 to 8 speeds, it was no small feat. Cassette hubs had just been introduced, and the freehub body had to be widened to fit the extra cog. There was plenty of room, but 9 speeds? That was too much. The answer was to make the chain narrower and do the same with the space between the cogs. The architecture of the derailleur itself didn’t change with regards to cable-pull, so it became more important that the cable and housing were kept in good shape. It’s one way that SRAM gained a small foothold at the time, because their shifters and derailleurs pulled more cable per shift, offering a wider margin of error. Since then, we’ve of course gone to 10, then 11 then 12 speeds, and the ability to adjust a derailleur is that much more important. So please, enjoy today’s installment of In The Stand.