[文章分享]登山車改48齒的錯誤迷思

*****************此圖示是簡單講述登山車的最基本:齒盤下陷高低和水平線的距離圖.


*****************此圖示是講述跑車最基本:齒盤下陷高低和水平線的距離.


********* 登山車鎖後變速器和後車輪軸心的距離尺寸.

*** 因登山車這段距離為2.7cm~3.0cm.是為了配合登山車後飛輪齒數(11~32齒或11-34齒)用及前大齒盤3盤使用.這樣才能使後變速器在做平行四連桿動作時的鏈條切線更順暢及有更多的鏈條包容量目數在後變速器內.以承受後飛輪作大齒數切換用.以供使用者做大扭力踩踏和前大齒盤3速切換用的.


********* 跑車鎖後變速器後後車輪軸心距離尺寸.



*** 因 跑車這段距離為2.4cm~2.7cm.是為了配合 跑車後飛輪齒數(11~21齒或12-23齒或12-25齒)用及前大齒盤2盤使用.這樣才能使後變速器在做平行四連桿動作時的鏈條切線更順暢及有快速得移動.以供使用者做大力踩踏時有更強的後變速器牽引張力和前大齒盤2速快速切換時不易於掉鏈用的.(所以此段溝爪距離不能太長2.4cm~2.7cm 即可)


＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊　此圖示是說明登山車後三角型和大齒盤下陷值／後飛輪和水平線夾角為３０度時的登山車簡單定義。


＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊　此圖示是說明跑車後三角型和大齒盤下陷值對應水平線夾角為６０度時和後飛輪時得跑車定義。



＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊　此圖示是說明大部分２７速登山車為何都搭配４４齒ｘ３２齒ｘ２２齒的齒盤組。並說明４４齒數的優點。


＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊　－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－此圖示是說明一般盲目車友一時衝動將原先４４齒盤組更改成４８齒盤組。因而有車友自認為４８齒比較重踩／跑比較快。。。。等等的錯誤迷失。




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*** 補述百分百確定要改48齒大盤的勇者/我所提共的拙見:***



若車友確定要改成48t大盤.也是可以的/但若單獨只改大盤是沒很大助益的.***要改48t大盤有2點要注意的地方:



1.就是先量測原車架齒盤中心和2輪水平線距離是多少尺寸.若是大於5.0公分則你可以更改它.



2.若沒有達到問題1的5.0公分數.則還有這個方法.就是先量測你原先前叉的總高度(從地面順著前叉量起--到--前叉碗下碗位置處)尺寸是多少:

**假設原前叉避震行程是100mm的.從地面順著前叉量總高度是85公分.***那你只需更換1支行程80mm的前叉(比原車前叉行程低或總高度低的前叉)/或換成硬叉(就是沒避震的前叉).那總高度下會下降~接連著車架的齒盤中心也會跟著下降.那後三角的虛擬幾何夾角就會變大.在這種狀況下你更換48齒大盤就是最佳的搭配了.



*** 以上拙見供車友參考.若有不對和不足的地方/還望前輩多多指導和指正.謝謝.


出自千里達單車