Chain Rotation Part 2 交替使用鏈條 (2)

Chain Rotation Part 2 交替使用鏈條 (2)

小藍Finest RC mileages: 2026 km in record. 嗯,該來換鏈條吧。

舊鏈條又是花了我一些時間清理才收起來。新鏈條我是用KMC”平價”的十速鏈條 。在裁鏈條之前,我先大對大比了一下。現在沒有舊鏈條擋路,發現其實所需的實際長度是只比52 links多了一點,約52.3吧。這跟先前用嚴謹公式估算的結果有點出入。我量了兩次都是一樣的結果 (我這是在做普物第一個實驗基本量測嗎?)。

為了謹慎,我先裁成53 links (含快扣),然後放入小對小查看是否過鬆。

Check also that the lower section of chain does not rub chain at upper pulley. (Park Tool Repair Help)

答案是會的,因為下方的鏈條會碰到上面的。然而這樣的長度在大對大時是會比較安心的。依據Park Tool Repair Help:

If the derailleur capacity does not match the gear sizes on the bike, the chain may appear to fail either the “too long” test or the “too short” test. A chain length cannot be found that will pass both tests. In this case it is better to size a chain for too long rather than too short. Both the EXISTING CHAIN and EQUATION methods below will safely size a chain when a bike is violating the derailleur capacity. It may be necessary to avoid gear combinations that cause problems in pedaling or shifting on these bikes.

Shimano 官方對Ultegra後變的total capacity是29T,然而我的情形是(50-34) + (28-11) = 33,是超過許多。Park Tool 的建議是以大對大的量測方法為準,車主應該避免用上小對小。可是我比較會不小心用上小對小;比起來,大對大的機會反而小很多。結論是,我還是用跟原來的長度一樣,52 links。

後話:看來我的前盤不夠大到可以利用上rigorous equation。Simple的已經夠用了。

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