What it does

Chain length tells you how many links you need for a new sprocket pair. It backs out the sprocket center distance from your stock chain and stock sprockets, then reapplies it to the new pair.

1. Check the inputs

1. Open Chain length from the hub. It uses the active bike.
2. Stock chain links: filled in for bikes from the database. For hand-entered bikes, count the links or take them from the manual.
3. Front now and Rear now: the sprockets you want. They start at the bike’s current sprockets.

2. Read the result

• The big number is the links you need, rounded up to an even count.
• Change vs stock, the exact calculated length, the chain pitch (1/2 in for 4xx, 5/8 in for 5xx, 3/4 in for 6xx chains) and the sprocket centers distance.
• How far the rear axle sits from where it does on the stock chain and sprockets. Check that it stays inside your adjuster range.

Example

A 2015 Yamaha YZF-R1 is listed with 16/41 sprockets and a 525 chain × 120 links. Going to 16/43 needs 122 links (+2); 16/47 needs 124.

Tips

Order the even count so the chain isn’t short, and measure slack before you cut or rivet. Belt-drive bikes have no chain to size, and the tool says so.

Where the numbers live

Everything here is saved in this browser on this device (the garage list, active bike, pulls and dyno entries). It doesn’t sync to other phones or browsers, and clearing the site’s data deletes it.