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CHAIN: LENGTH AND WEAR

To calculators

The 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 consider
Length in links How much to withdraw Wear and tear, % 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
The desired chain length
114 звеньев
The same length in millimeters
1448 mm
In centimeters
144.8 cm
A chain of 116 links
from 116: remove2link
A chain of 126 links
from 126: remove12links

The formula: 2 × (425 / 25.4) + (40 + 52) / 4 + 1 = 57.46″, это 114.93 звеньев по 12.7 mm, округляем до чётного — 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 out on
+1.50 mm
Threshold by ruler
306.32 mm
It's left to the threshold
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.

Denomination 12 звеньев — 304.8 mm (мерят от центра пина до центра пина). Для 12ск порог 0.50 %, то есть 306.32 mm: прикладывай линейку и смотри на эту цифру. Above 1%, the cassette is almost certainly gone — then change the kit.

3. Resource and next check
It remains approximately
1000 km
Resource developed
60 %
The next measurement with a ruler
through500 km
Half of the resource is behind — it's time to start measuring regularly.

Conditions "Переменно: пыль и дождь» дают 2000–3000 km, уход «Иногда вспоминаю» двигает оценку в 0 % — получается 2000–3000 km, в расчёте берём середину: 2500 km. Мерить износ имеет смысл каждые 500 km. Цифры ориентировочные: линейка честнее любого пробега, потому что цепь убивает не километраж, а песок с водой.

How to use it

Chain length — the classic formula is L = 2 × (feathers in inches) + (teeth of the big star + teeth of the big star cassette) / 4 + 1. We turn the result in inches into links: one inch of chain is two links of 12.7 mm each. You can only put a chain with an even number of links, so we round it up to an even number.

The practical method — put the chain on the big star in front and on the big star of the cassette, bypassing the rear derailleur, bring the ends together and add two links. For 1x — the same, but then be sure to check that the switch frame does not straighten into a line on the small star of the cassette: this is a sure way to break the switch on the first bump.

Checking the switch — both the formula and the girth give only a starting point. The correct length is confirmed by the switch: on a large, large frame should not straighten, on a small, small chain should not hang in a loop. For long frames and mullet assemblies, the formula regularly underestimates the length by a couple of links.

Wear and tear — 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 millimeters — 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.