- Shimano Saint rear derailleur
The key word with Shimano's Saint rear derailleur is "survivability". Derailleurs work amazingly well, and actual performance-enhancing developments tend to be, to put it diplomatically, incremental. But Saint is a ground-up heavy-duty component group, and dangly derailleurs are a notorious weak spot. They have a nasty habit of taking bits of the frame with them, too.
The Saint mech's most obvious defence is that it doesn't rely on a derailleur hanger on the frame. Instead it attaches directly the the end of the rear axle. This means that you have to use the Saint rear hub too, but before the conspiracy theorists start foaming at the mouth it's a perfectly reasonable requirement. For a start, the hub's pretty decent, but the new design has clear benefits.
The axle mounting and the design of the upper knuckle of the derailleur means that in a typical bike-falls-over-sideways crash the first thing to hit the ground is the big lump of metal right at the end of the axle. So that big rock you just dropped your bike on ends up thwacking the end of the axle rather than a sticky-out bit of derailleur that'll lever the gear hanger off the frame.
The cable anchor point has been moved from underneath the parallelogram to on top so it shouldn't attract the attention of any passing rocks and the cable end is tucked neatly away and won't catch on anything. As well as the traditional B-tension adjuster screw, there's an adjustable bump-stop to prevent the mech clouting your chainstays over rough ground.
The variety of front ring setups available with Saint has led Shimano to offer the rear derailleur in three lengths, so you can run a shorter one if you don't have a load of chainrings to deal with.
And now the bit you've been waiting for. Yes, Saint is Low Normal only - click an RF+ pod with your thumb and you'll get a smaller sprocket. Our initial scepticism of this concept has gradually diminished as we've got used to it, and while we still occasionally miss being able to grab a thumbful of low gears there's no denying that the spring-driven downshifts are super-smooth. Indeed, shifting performance generally is well up to the standard that we expect.
The only real downsides to the Saint mech are the fairly hefty price, the requirement to run a Saint hub too and, for some riders, Low Normal. You can, after all, buy a few replacement conventional mechs for the price of a Saint mech, rear hub and wheel rebuild.
Positives: As bombproof as rear mechs get, smooth performance, Low Normal
Negatives: Component dependencies likely to prove offputting, Low Normal
Verdict: This is probably the most controversial bit of the Saint group. We'd have to say that it's probably not worth ditching your existing rear hub (and possibly brake) just to run one of these, but if you're building from scratch then it's great as long as you can get your head around Low Normal...