Assembly instructions:
Step 4
Connect curved tube #7 and rear support tube #8 together. Attach the upper
end to the top bar #1 using bolt #13 and Allen wrench #18. Secure the lower
end to the right base tube #5 and use bolt #12, washer #16, nut #14, Allen
wrench #18, and wrench #17 as shown in the enlarged diagram. Repeat the
same process on the other side.