Step 2:
16
16
8
17
16
8
17
16
8
17
#8 d8 8PCS
15
26
13
#65 S13-14-15 1PC
Take out the bolts(16), spring washers(8) and washers(17) by wrench(65), then
attach front bottom tube(15) and rear bottom tube(26) on the main frame(13) with
wrench(65), bolts(16), spring washers(8) and washers(17).