▁ ▁There ▁are ▁many ▁ways ▁to ▁build ▁a ▁vel om obile . ▁ ▁One ▁modern ▁design ▁is ▁" body - on - frame ", ▁in ▁which ▁a ▁vel om obile ▁is ▁made ▁from ▁a ▁not - fa ired ▁cycle ▁plus ▁a ▁body . ▁ ▁A ▁standard ▁cycle ▁may ▁be ▁used , ▁but ▁often ▁a ▁custom ▁cycle ▁is ▁used ▁with ▁special ▁f itt ings ▁to ▁mount ▁the ▁body ; ▁the ▁use ▁of ▁special ▁f itt ings ▁tends ▁to ▁improve ▁fit ▁and ▁dur ability , ▁and ▁can ▁also ▁reduce ▁weight . ▁ ▁Body - on - frame ▁construction ▁allows ▁flexible ▁configuration : ▁the ▁body ▁may ▁be ▁of ▁any ▁construction , ▁as ▁it ▁does ▁not ▁need ▁to ▁be ▁self - support ing , ▁and ▁various ▁bodies ▁can ▁be ▁used ▁with ▁various ▁frames . ▁ ▁Also , ▁the ▁body ▁may ▁be ▁removed ▁so ▁the ▁cycle ▁alone ▁can ▁be ▁used . ▁ ▁However , ▁the ▁overall ▁weight ▁of ▁body - on - frame ▁is ▁often ▁higher ▁than ▁alternatives , ▁as ▁the ▁body ▁does ▁have ▁some ▁intr insic ▁strength , ▁yet ▁this ▁is ▁not ▁used ▁to ▁reduce ▁the ▁weight ▁of ▁the ▁frame . ▁ ▁Another ▁modern ▁design ▁is ▁the ▁Alle w eder , ▁using ▁al umin um ▁sheet ▁formed ▁and ▁riv et ed ▁to ▁make ▁the ▁fair ing ▁and ▁the ▁structure ▁in ▁one ▁piece . ▁ ▁This ▁approach ▁is ▁sometimes ▁called ▁mon oco que ▁or ▁" unit " ▁construction ; ▁it ▁was ▁used ▁in ▁air plan es ▁before ▁ 1 9 2 0 ▁and ▁has ▁been ▁used ▁commonly ▁in