"We go to the park for a picnic by biking" 可以用 "We bike to the park for a picnic"来表达。
"Bike" 是英语中 "骑自行车" 的意思，来源于英语单词 "bicycle" 的缩写。
例句1:
"We're going to bike to the park for a picnic this afternoon."
(我们下午要骑自行车去公园野餐)
例句2:
"Do you want to join us for a picnic in the park? We're biking there."
(你想不想和我们一起去公园野餐？我们会骑自行车去的)