Nice pictures

A Closer Look at String Tension

Most tennis players choose a tennis racquet with great care, but many don't realize that their racquet's stringing may have a more profound effect on their game than their carefully chosen frame.

At a minimum, every tennis player should understand the basic trade-offs between power and control in relation to string tension. Any decent tennis racquet will have a recommended range of string tensions, for example 58 to 68 pounds. When we talk about low or high tension, it makes sense to confine ourselves within this range, because at extremes below this range, some of the normal correlations break down.

Within the recommended tension range, lower tensions offer slightly more power and significantly less stress on the arm, and higher tensions offer significantly more control and slightly better spin.

Looser strings hit farther in part because the ball stays on the strings longer, and because on most swings the racquet tilts upward and rises as it moves forward, a ball that stays on the strings longer leaves the racquet on a higher trajectory. The key to understanding the other reason that lower string tensions yield more power is to compare the energy return offered by the strings to that offered by the ball.

If you read the official rules of tennis, you'll find a section that specifies that the ball, when dropped on concrete from 100 inches, shall rebound to between 53 and 58 inches. In any collision, some energy is lost to vibration and friction, and in the case of a tennis ball, a huge amount is lost in deforming the ball's materials. As the ball hits the concrete, part of it compresses, and the rubber stores some of that energy, which is then released as the ball uncompresses. If all of that energy were stored with perfect efficiency, the ball would bounce right back to 100 inches, but as a tennis ball is designed, it dissipates around 45% of that energy. A "Superball" is better at storing its compression energy, and it will bounce back much higher when dropped from the same height, but a ball that could bounce back to 100% of its original height is still a physical impossibility, even in a vacuum. If such a ball were possible, it would bounce forever.

1/16/2013 被66機車行框了

今天去新店寶橋路的66機車行換輪胎，本來是想去公館的大佳機車行換，結果突然下雨，只好就近換。一條瑪吉斯的M-6029報NT$1600，另一條說是正新的(型號不知，應該是光陽原廠胎)報價NT$1400，雖然知道有被貴到，但是想說給老闆賺一點，很久沒來交關了。沒想到上露天一查，M-6029裝到好1300，正新的好像1000左右，摃盤子啊！

2012 香港行

My favorite picture of this Hong Kong tour!

Mio market

Tennis Club Account Book

String Tension

String Tension(上線高低峰值): 53-63 pounds (磅)
非力士浪硬線，本著先上拍子推薦的中值，再根據手感調整。相加力量的，減少磅數，想加控制的，加磅數，每次調整2-3磅。
力 士浪硬線主打線(非zolo和Poly)要比推薦的中值減少10%左右。尤其是Timo和Alu power這兩款，加了鋁纖維，有很大的震動，手臂力量不足或動作不夠規範的人容易打出網球肘。美國的羅迪克fans用PD+這種硬拍子上硬線加到60磅 以上，打傷者慎多。
再次提醒職業選手的上線不可取!!!阿加西用OS拍為了加強控制，alu power上了67磅。問題是我們沒有他們那樣好的身體素質。用PD/PD+的人若非有勝於羅迪克的身體素質，千萬不要上線超過60磅。
切記：打 出網球肘的人都是被自己的力量打傷的!力量小或不喜歡自己的發力的人一般傷不了。只有硬拍加硬線加不協調地發力(手臂用力過多)才是致傷的主要因素。
球 線問題：
拍子裡是不加線的，但買拍子的人都要上線的，所以就大概說明一下球線的情況。
現在主要是尼龍線/合成線等、聚脂線、天然腸線這三 類。
合成線、尼龍線或是說仿腸線，都是為了節省成本，在一定程度上追求腸線的效果，所以都有一個通病，不禁打。大力選手用這類線最易斷。
聚 脂線也就是大家通稱的硬線，以力士浪的為典型代表，非有一定水平的選手，是不會把這種線打走的。好處不用說了，不用理線，不愛斷，力量足，壞處也眾人皆 知，水平不濟者，用它會反而傷手。
天然腸線，用這線能打出網球肘的人目前沒聽說過。三頭牛的腸衣才能做出一條天然腸線，貴就一個字，爽也就一個 字。有錢人追求手感舒適者必選。專業選手的不二選擇。如果說硬線讓大家第一個反應到的就是力士浪系列線的話，天然腸線則是Babolat最大的王牌。
最 後說明，新手/女士建議使用仿腸線，手感舒適，也經濟。不用擔心會把線打斷，對新手來說，半年之內是不會斷線的。那些說這線不結實那線愛斷的，一般都是打 球有一定水平，發力充分的大力選手，以休閒為目的打球的人，是不用擔心球線經常斷的。
對於掌握基本正反手技術後，需要增加球感或尋找上旋感覺的朋 友，建議用一用細線，17(1.21mm-1.30mm)或18(1.20mm-1.10mm)線徑，吃球的感覺會很爽的。
有些有不規則紋路的表 面粗糙型球線如alu power rought或5 star，產品說明都說有利於增加擊球的上旋效果。對此我的建議是：如果技術不在3.0之上，不要幻想用它來增加自己的上旋了。想增加上旋，效果依次是: 技術>>>線床密度>>線的粗細>線的表面是否粗糙。