我覺得應該是stood up, 或 be standing up都可以為何是用過去式,按文法應該是剛才有站起來,現在沒有如果要表達---使勁加速,並保持站立的姿勢我可能會寫 He stood and rode at full speed.
這個網頁有提到一些公路車的騎乘姿勢http://www.smartcycles.com/fitting_explained.htm 可參考一下其中有 Seated Ride, Out of Saddle Sprint, Seated Climb, Out of Saddle Climb,Seated Descent 等的 姿勢介紹