Not 45 days, not a year: lock new XBT for 100 days

The fight over XBT's coinbase lock has split into two camps. One wants to jump straight to a year. The other wants to keep 45 days and see what happens. We think both are wrong. Lock new block rewards for 100 days, as a temporary soft fork that expires on its own after one year.

Where the fight stands

A poll in the Bitcoin Knots Discord asks whether to extend the 45-day lock on newly mined XBT until the RDTS soft fork expires, which community members put around September 2027. Our news story covers the details.

• Go long now. Dave (@davelund_): "We're going for 1 year. Nodes run Bitcoin."
• Stay at 45 and wait. PepeLapiu (@LapiuPepe): "Let's start at 45 days rolling CBM. If that doesn't work we can increase it."
• Vote no. Greater Good Mining (@Gr8erGoodMining) is urging miners and hash renters to vote NO on the poll.

One correction to the alarm going around: a longer lock doesn't stop miners from getting the blocks they find. Every reward is still theirs. It just can't be spent or sold until the lock runs out.

45 days isn't doing the job

The lock exists to slow down hash rate that shows up only to mine and dump. The 45-day lock has been in force since block 973,440, and the hash rate kept pouring in anyway. Difficulty rose 9.98% at the last retarget and is on track for about another 17% around Oct 17. Blocks are coming every 8 and a half minutes. That's not a network where short-term hash is staying away.

Waiting to see if 45 days works has a cost, too. About 20,250 XBT locked under the current window starts unlocking around the end of October, at roughly 450 XBT a day. Whatever the community decides needs to be in place before the next wave, not after it.

A year breaks the wrong people

A lock hurts renters far more than owners, at any length. Someone renting hash pays roughly what that hash earns, up front. Someone running their own machine only pays for power. Here's what each one has to front before they can sell a single coin, using one 19 TH/s BLAKE2b miner at today's difficulty and price, with power at $0.13/kWh:

At 100 days, renting hash means tying up about three months of rent with price risk the whole time. That's where short-term hash stops making sense. A home miner can carry three months of power bills.

At 365 days, the home miner is out a year of power before the first sale, and most small miners can't float that. Pools pay their miners out of block rewards, so a year-long lock means a year of float, and only the biggest, best-funded pools can do that. Hash would pile into fewer pools, the exact problem we wrote about in They can't just switch pools. Lots of hash rate would leave at once, and the chain would be cheaper to attack while difficulty catches up.

Dave is right that nodes run Bitcoin. Nodes set the rules. But a rule that drives off the small miners who keep XBT decentralized is a bad rule, even if the nodes can enforce it.

Our pick: 100 days, ending in one year

• Every new block reward locks for about 14,400 blocks, which is 100 days at the 10-minute target. Each reward unlocks 100 days after it's mined, block by block, so there's no single unlock cliff.
• It's temporary. It applies to blocks mined over the next year, then maturity drops back to the normal 100 blocks. Nobody has to win a second fight to remove it.
• It can be revisited. If rental hash keeps flooding in at 100 days, the community has real data to argue for longer. That's PepeLapiu's step-up idea, starting from a number that bites.

Unlock countdownThe vote, explained

Opinion. Not financial advice. Cost figures use the xbt.live mining calculator (iBeLink BM-S3, 19 TH/s, 3,100 W, $0.13/kWh) at Oct 10 difficulty and price, and assume hash rental costs about what the hash earns. Real numbers will move with price and difficulty. Quotes are from public posts on X.