>>1374297Product Details
Shimano Altus Rear Derailleur
> The best-designed cheap rear derailer in existence. Most derailers have 11t pulleys, and that works well. The ALTUS has a 13t top pulley and a 15t bottom one, and what's the big deal there.> The bigger pulleys "use up" more chain, so the derailer cage that houses them don't need to be as long and low-hangy. Plus, the bigger pulleys turn more freely. There is no reason on godsgoodearth that all derailers shouldn't have big pulleys, and maybe someday they will. But for now it's the ALTUS, a super-shifting Shimano.> This is my/Grant's personal favorite rear derailer, but that doesn't mean it should be yours. I like it because the pulleys are huge (13t for the top one, 15t for the bottom one, compared to 11/11 on a normal rear derailer). This means they take up more chainslack and don't need as long a cage. The bigger pulleys turn easier, too. I don't care about that, but I find it interesting that Campagnolo retrofits giant pulleys on its derailers for pro riders sometimes, to reduce turning friction.> The thing I really like is that Shimano introduced this big-pulley design near the low-end of its range, probably because they felt it was too risky to introduce on their elite models, figuring the low-brows wouldn't be as tradition-bound. So there it is: Shimano's best design in a cheap derailer. There are now becoming some other Altus variants. The groovy one is the M310.Indexes 7 or 8 speed, frictions up to 9.
Wraps 43 teeth*.
Max rear cog, 34t
Wt: 318g
https://www.rivbike.com/products/shimano-altus-rear-derailer-rd-m310-17167 