23–24 January 2027 · Veliky Novgorod
ЗИМНИЕ ВЫХОДНЫЕ ВЕЛОКРОССА · 3ВВ
Два дня ТИПАЦИКЛОКРОССА: Cyclocross, Gravel, Fixed gear, МТБ и беговой кросс. Один день или оба.
CHAIN: LENGTH AND WEAR
To the calculatorsThe workshop is on one page: how many links should be in your chain and how many to remove from the new one, whether the chain is alive according to the ruler and at what figure in millimeters it is time to change it, how many more kilometers it will endure in your dirt.
How to measure wear and check chain length
What we count
Length in Links
How much to remove
Wear, %
Threshold in mm
Resource, km
When to measure
The recalculation goes by itself, there are no buttons. The link to the page saves your numbers — you can throw the mechanics into the chat instead of long explanations.
1. Chain length
Required chain length
114 links
The same length in millimeters
1448 mm
In centimetres
144.8 cm
Chain with 116 links
from 116: remove2link
Chain with 126 links
from 126: remove12links
The formula: 2 × (425 / 25.4) + (40 + 52) / 4 + 1 = 57.46", this is 114.93 links of 12.7 mm, rounded to an even number — 114.
Practical method: girth over the big star and the big star of the cassette past the switch — 1436mm, these are 113.1links; plus two links - 116. The difference with the formula +2link.
This is a starting point, not a verdict: the correct length is checked by the switch. Scroll the chain to the big, big one and make sure that the frame does not straighten into a line, then to the small, small one - the frame should not rest and the chain should not hang out. At 1x, checking for a small, small one is also mandatory: there the switch straightens up easily and tears up its frame. For switches with a long frame and for mullet assemblies, the formula often gives a couple of links less than you need - keep in mind the option on 116links.
2. Chain wear
Chain extension
0.49 %
Stretched to
+1.50 mm
Threshold by range
306.32 mm
Threshold left
0.02 mm
It's time to order. There is not much left before the threshold: order the chain in advance so as not to look for it in a panic before the race.
The nominal value of 12 links is 304.8 mm (measured from the center of the pin to the center of the pin). For 12sk, the threshold is 0.50%, that is, 306.32 mm: put a ruler and look at this figure. Above 1%, the cassette is almost certainly gone — then change the kit.
3. Resource and next check
Approximately left
1000 km
Resource depletion
60 %
Next measurement with a ruler
through500 km
Half of the resource is behind — it's time to start measuring regularly.
The conditions "Variable: dust and rain" give 2000-3000 km, the care "Sometimes I remember" moves the estimate to 0% — it turns out 2000-3000 km, in the calculation we take the middle: 2500 km. It makes sense to measure wear every 500 km. The figures are indicative: the ruler is more honest than any run, because the chain does not kill mileage, but sand and water.
How to use this
Chain length — the classic formula L = 2 × (chainstays in inches) + (teeth of the large chainring + teeth of the large cassette sprocket) / 4 + 1. The result in inches is converted to links: one inch of chain is two links of 12.7 mm. The chain can only be installed with an even number of links, so round up to an even number.
Practical method — put the chain on the largest chainring in front and the largest cassette sprocket, bypassing the rear derailleur, bring the ends together and add two links. For 1x — the same, but then be sure to check that the derailleur frame does not straighten into a line on the smallest cassette sprocket: this is a sure way to break the derailleur on the first bump.
Derailleur check — both the formula and the measurement give only a starting point. The correct length is confirmed by the derailleur: on the largest-largest the frame should not straighten, on the smallest-smallest the chain should not hang in a loop. Long frames and mullet builds regularly underestimate the length by a couple of links.
Wear — we consider the elongation as (measured − nominal value) / nominal value × 100. The nominal value of 12 links is 12 × 25.4 = 304.8 mm, 24 links are 609.6 mm; measured from the center of the pin to the center of the pin by pulling the chain. Threshold: 0.5% for 11 and 12 speeds, 0.75% for 9-10, 1.0% for 8 and less. Above 1% — the cassette is almost certainly gone, to change the kit.
Threshold in millimetres — reverse calculation: the same length at which it is time to change the chain. For 12 speeds on 12 links, this is 306.32 mm. Remember the figure, attach a ruler — and do not count the percentages in your mind on the sidelines.
Resource — reference point: 3000-5000 km in dry and clean, 2000-3000 in variable weather, 1000-1500 in mud and sand, 700-1200 in winter with reagents. Regular washing with grease adds up to 30%, complete indifference takes the same amount.
All figures on the resource are indicative: the ruler is more honest than any run. The chain does not kill mileage, but sand and water — one trip on wet gravel can eat more than a month of dry asphalt.
