What an Actual Bitcoin Hard Fork Looks Like: The BLAKE2b Fork Swapped the Mining Algorithm, and 97% of Hashrate Chose Not to Follow

If existing mining machines couldn't mine on the new chain at all, where did the new chain's initial hashrate actually come from? With no hashrate, how could the chain function normally?

What made this new chain actually able to launch comes down to BLAKE2b not being a brand-new invented algorithm — it's a hashing algorithm Siacoin has already run on for years. That meant there was already a pool of ASIC miners purpose-built for mining Sia sitting in the market, some of it idle due to Siacoin's own market conditions (a lower coin price, mining that no longer paid off). The BLAKE2b fork team essentially inherited this already-existing but underutilized hardware hashrate directly, without needing to convince anyone to buy entirely new equipment from scratch.

That's also why the fork team specifically noted their algorithm was "selected by deterministic draw from a shortlist" — choosing an algorithm that already had a ready-made hardware base, rather than designing a brand-new algorithm with no corresponding hardware on the market at all, was a key strategic consideration that let this new chain avoid the more fundamental problem of "zero hashrate, chain halts immediately." That said, even after borrowing Sia's hardware base, the actual hashrate flowing to this new chain remains vastly smaller than the original Bitcoin mainchain's hashrate.

An earlier article on this site discussed how Solana's Alpenglow doesn't count as a hard fork — this BLAKE2b fork is being called an "actual hard fork." What's the key difference in classification criteria?

The criteria are exactly the same — this event just sits at the opposite end of the spectrum. Fork classification was never about how big the rule change is; it's about whether there's a mechanism deliberately preventing a split from happening between old and new rules. Alpenglow's new and old consensus rules genuinely are incompatible, but through its feature-gate mechanism — requiring an overwhelming majority of staked weight to upgrade before triggering the switch — it directly forecloses the possibility of an old-rules chain surviving by design. The BLAKE2b fork is the exact opposite: incompatibility between old and new mining algorithms is a given fact, and the fork team never intended to wait for majority hashrate agreement before switching in the first place — they actively chose to shake off existing miners, letting old and new chains exist independently at the same time. That's precisely the defining trait of a hard fork: the split itself is a designed-in, even deliberately pursued, outcome.

What makes this event especially useful as a comparison point is that it demonstrates the most extreme form on the hard-fork spectrum — not just incompatible rules, but a replacement of the underlying proof-of-work algorithm itself, meaning the old and new chains no longer share even hardware-level compatibility. That's a more thorough split than classic hard-fork examples like Ethereum/Ethereum Classic.

With only roughly 2% to 3% of hashrate supporting this fork, does that low level of support mean the entire fork effort can be considered a failure?

Judged by the standard of "could it replace Bitcoin's mainchain," this fork genuinely fell far short of that goal — market consensus remains heavily concentrated on maintaining the existing SHA-256d mainchain, and the new chain has almost no exchange, wallet, or Lightning Network support, all objective facts pointing to the market simply not endorsing this new chain's value proposition. But from a different angle — judged by whether the new chain technically launched successfully and actually produced blocks — the fork team genuinely did achieve the specific technical goal they set out to accomplish: the algorithm genuinely was swapped, the new chain genuinely is producing blocks, and the first BLAKE2b Block genuinely was mined at 961,640.

These two evaluation standards get conflated often, but they're actually completely different tiers of question — "can it technically run" is an engineering question, while "is the market willing to assign this chain real value" is a social-consensus question, and the answers to the two don't necessarily line up. Historically, most minority forks end up in exactly this state — technically real, but with market value trending toward zero — because a chain's long-term value ultimately depends on whether enough people are willing to keep using, trading, and maintaining it, not on how radical its technical changes were.

If I hold Bitcoin and see news about this kind of hard fork, how do I actually judge whether it affects me and whether I need to take any action?

The first step is always checking whether official documentation and mainstream coverage explicitly use the term "hard fork," and confirming the new chain's actual market support — if, as in this case, the overwhelming majority of hashrate, exchanges, and wallet providers all chose not to follow, that indicates the market has strongly settled on maintaining the original mainchain, and the Bitcoin you hold isn't materially affected by this minority new chain's emergence at all — no action is needed.

Second, if you see any message urging you to "transfer assets," "swap for a new Token," or "register to claim an Airdrop" during the fork window, that request itself is a signal worth being wary of — a genuine Bitcoin holder doesn't need to take any action for this kind of fork, and any message urging you to actively do something is usually an early warning sign of fraud. Third, if you're personally interested in this new chain itself — say, wanting to try mining with idle Sia hardware you already own — understand that this is a completely independent asset with extremely low market recognition, severely limited exchange support and liquidity, and a completely different tier of risk consideration than holding or trading Bitcoin itself.