First-time Hub Overhauling (+ Remove Cassette) 初次花轂檢修 (+ 拆飛輪)

First-time Hub Overhauling (+ Remove Cassette) 初次花轂檢修 (+ 拆飛輪)

嘗試了好幾次自己拆飛輪,但就是不成功。只好去找機械工廠的田先生幫忙,終於卸下了飛輪(10/14)。田先生擺置chain whip (飛輪固定鍊) 及 adjustable wrench (活動扳手)的方式與其他的不同。

Method 1:左手拿wrench,右手拿chain whip (如Bike Tutor的示範),向內施力。
Method 2:左手拿chain whip,右手拿wrench (如Bikeradar的示範),向外施力。

Method 1 好施力但主要施力在左手(右手是固定用),所以對右撇子又是女生來說不易施與大力。Method 2 不好施力,因為用不上身體的重量。此外還要有東西頂住輪子。

田先生用的方式是Method 2的拿法,但是將兩者擺在同一側(面對輪的右邊);有點像是這個符號”<“。我覺得這個方法不錯。Anyway,拆下飛輪後,又裝回去,我練習一下怎麼拆。提起我覺得輪子轉得不順時,田先生說那要不要拆花轂來看看。Well, why not?

結果拆這種標準花轂 (cup-and-cone hub) 比我想像中要容易。我沒有上去把cone wrench (花轂扳手)拿下來,田先生直接就用兩個活動扳手就行了。

(圖源)

花轂裡面當然是髒兮兮的,而且非傳動側那邊是最髒的,看來還有鐵屑的樣子 (田先生說)。拆下的零件及滾珠都用溶劑 (當下只有拿WD-40狂噴) 清洗。要裝回去時,才發現非傳動側(左側)的cone損害滿嚴重的。兩邊的cone比較:

田先生建議,這樣不要裝回去了,因為只會使磨損更嚴重,甚至會損害滾珠。我還傻傻的問這外面買不買的到,田先生說恐怕得向車店問才能找到零件來更換。

我就帶著拆下的軸承 (就是上上圖的東西) 去車店問。車店說先前也有人有反應過這個問題 (我不知道是不是同款車),說要把整個後輪送回原廠去修,還說我不應該自行拆。我又不知道可不可以當場修好,如果不自己拆下來,我怎麼騎我的通勤車把後輪帶過來? 很不方便耶!店家說剛好她們可以借給我一個後輪。唉,就怪我太過自動自發了。

後來請小夢幫忙隔天載我去換後輪 (沒有將軸承組回去)。借給我的是Alex R-390,好像是Roubaix的輪組。不知道是不是因為用的是Novatec “培林”花轂的原因,用手拿著轉起來很滑順,完全沒有Alx-200的顆粒感。

拆下T3的輪組 (聽說也是很爛) 拿來轉一轉。前輪略有顆粒感,後輪比前輪好一點點 (但都比Alx-200要好)。是不是Cup-and-cone hub的輪組都會有這種顆粒感嗎?

Bicycle wheel bearings, as most, require a slight preload so that more than one ball under the cone (inner race) will support its load. With proper preload, slight drag should be perceptible. Preload drag is small compared to drag caused by wheel loads, neither of which are significant regardless of adjustment. In contrast bearing life is affected by proper adjustment. Adjusting ball bearings to spin freely unloaded does not reduce operating friction because a bearing with proper preload has lower drag when loaded than one with clearance. For high quality bearings, preload should be just enough to cause light drag when rotating the axle between thumb and forefinger. Low grade bearings will feel slightly lumpy with proper preload. (Jobst Brandt)

還有這裡

You want to result with an adjustment that is not loose – no side-to-side play in the bearing with the wheel on the bike. This is crucial. The rear hub adjustment can be checked with the wheel off the bike. Axle should rotate as smoothly as possible but with NO PLAY. Cup and cone bearings require there be no play, even if the bearing feels a bit “grainy” when adjusted to the point where the play disappears. (From here)

我正試著搞懂這兩段話。 所以,手持著旋轉會有點的顆粒感是正常的?但不可以左右移動?

Further readings:

1. 很多中文自行車維修書都沒有對cup-and-cone hub的拆解最解說,大多是針對cartridge-bearing hub (卡式軸承花轂)。有需要,請參考Sheldon BrownBikeradar或是Bicycle Tutor等網站。

注意,cone adjustment是很重要的,會影響花轂的壽命。除了Sheldon Brown文章外,另見Jobst Brandt’s Wheel Bearing adjustment及這位網友的說明 (比較易懂)。

一般人以為cartdridge bearing是培林花轂,cup-and-cone hub是滾珠花轂。其實用詞又是錯誤 (總是別人用了就跟著亂用)。cartdridge or cup-and-cone都是bearing (軸承),只是形式不同。

2. 輪組快拆 (quick release skewers)的正確使用對cone adjustment (or wheel bearing adjustment)是很重要 (詳見1.列的網站)。

Richard Ballantine on “City Cycling

The amount of force necessary to close should be neither minuscule nor titanic. There should be enough resistance to leave a momentary dent in the palm of your hand.

力量不能太小也不能過大。大到足以在你手掌下暫時留下印痕。我也在摸索這個。當我第一次要拆快拆時,店家鎖得好緊,我要扳下來非常地困難,幾乎是用盡力氣才扳開。這樣不會鎖太緊了嗎?

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