I spent three months in 2021 testing the Altered Cycle ZIP on a mid-travel Santa Cruz Tallboy. Here is the unfiltered verdict.
In the world of high-end cycling, the drivetrain is the soul of the machine. By 2021, the market was saturated with electronic shifting—SRAM AXS and Shimano Di2 dominated the peloton. But a small, rebellious brand from the Pacific Northwest, Altered Cycle, decided to go the other way.
Enter the Altered Cycle ZIP 2021—a mechanical, continuous-loop, belt-drive compatible shifting system designed to mimic the tactile feel of a precision rifle bolt-action while offering the lowest maintenance profile on the market. The “ZIP” refers to the sound and speed of its rear cassette engagement, which, according to early testers, sounds like tearing a piece of tape at 50 mph. altered cyle zip 2021
This article explores every facet of the 2021 model: its engineering, unique selling points, failures, and why it remains a cult classic three years later.
Note on terminology: While the search query reads "altered cyle zip 2021," we are addressing the Altered Cycle ZIP—a niche, high-performance bicycle component system. If you reached this page looking for automotive ECU tuning, software patches, or gaming file archives, please adjust your search. Here, we focus on the 2021 iteration of the Altered Cycle ZIP drivetrain. I spent three months in 2021 testing the
Standard cassettes have uniform tooth shapes. The ZIP uses a variable geometry where every fifth tooth is 0.2mm taller and offset. This "altered" tooth catches the chain only under load, preventing the dreaded "chain suck" that plagued earlier prototypes.
If you find one new-in-box on eBay or a forum classified, expect to pay $450–$600 (the 2021 MSRP was $349). Is it worth the premium? Skip it if:
Buy it if:
Skip it if: