ZTTO Ultimate 11/12 Speed Road Bike Cassette Ultralight 11s 12s 11-28/30/32/34/36T Gravel Cassette 11V 12V Black Freewheel HG K7

The reviewer analyzes the ZTTO SLR Gen 3 ultralight cassette, focusing on a specific failure case where the top two sprockets sheared off. They describe the cassette's construction: the top three sprockets are milled from a single aluminum block, with the rest being monolock steel, resulting in significant weight savings (117g vs. 260g for Shimano 105). The reviewer has personally used smaller versions (11-28T) for thousands of miles without issue but identifies a critical design flaw in larger sizes (11-30T and above). In these larger cassettes, the top two sprockets are connected to the third by a thin ring of supports, creating a potential cantilever beam effect and stress risers at sharp internal corners. This design, combined with spiky power delivery (e.g., in cyclocross) and the increased flexibility of larger sprockets, increases the risk of failure. The reviewer concludes that these cassettes prioritize minimal weight and low cost over structural safety margin and long-term durability. They advise caution, particularly for the 11-36T and 11-34T versions, and suggest stronger alternatives like ZTTO's all-steel or Gen 2 cassettes. They also note the shifting performance is decent but not as good as OEM, the cassettes are noisier, and aluminum teeth can snap if shifting under load.

The reviewer discusses their experience with a ZTTO monoblock cassette, which appears to be the ZTTO Ultimate 11/12 Speed Road Bike Cassette, though the exact model name isn't explicitly stated. They mention purchasing it for £66 and highlight its lightweight design at 200g, comparable to Shimano Dura-Ace. The cassette initially shifted well but wore out after approximately 2,500 miles, with the eighth gear becoming completely unusable. The reviewer conducted a hardness test comparing it to Shimano cassettes, finding the ZTTO's steel hardness relatively good but less uniform in hardening. They note the cassette has a basic black oxide coating rather than the more durable nickel plating found on Shimano products. The reviewer replaced it with a newer ZTTO SLR Gen 3 model but expects even lower durability due to aluminum teeth on the smaller cogs.

The reviewer discusses the ZTTO Ultimate 11/12 Speed Road Bike Cassette, highlighting its performance and value for money. They mention using it on multiple group sets and finding the shifting to be consistently good.