que ▁so ▁that ▁they ▁can ▁quickly ▁achieve ▁the ▁speed ▁required ▁to ▁complete ▁loops ▁within ▁the ▁sphere . ▁Many ▁rid ers ▁may ▁also ▁have ▁to ▁go ▁from ▁high ▁spe eds ▁to ▁a ▁dead ▁stop ▁very ▁quickly . ▁While ▁mass ▁market ▁b ikes ▁are ▁che aper ▁to ▁use ▁in ▁the ▁glo be ▁many ▁rid ers ▁custom ize ▁their ▁b ikes ▁to ▁their ▁lik ing ; ▁this ▁is ▁because ▁the ▁glo be ▁of ▁death ▁st unt ▁does ▁not ▁require ▁a ▁bi ke ▁with ▁a ▁powerful ▁engine , ▁susp ension , ▁and ▁drive ▁train ▁as ▁they ▁require ▁a ▁top ▁speed ▁of ▁only ▁ 4 0 ▁to ▁ 6 5 ▁miles ▁per ▁hour ▁or ▁ 6 5 ▁to ▁ 1 0 5 ▁kilometres ▁per ▁hour . ▁ ▁Stock ▁d irt ▁b ikes ▁are ▁limited ▁and ▁so ▁perform ers ▁modify ▁the ▁b ikes ▁in ▁order ▁to ▁make ▁the ▁st unt ▁sa fer ▁and ▁easier . ▁ ▁Physics ▁ ▁The ▁physics ▁of ▁the ▁trick ▁are ▁centered ▁around ▁the ▁manip ulation ▁of ▁cent rip etal ▁force . ▁This ▁is ▁the ▁force ▁that ▁acts ▁on ▁an ▁object ▁as ▁it ▁moves ▁around ▁in ▁a ▁circular ▁path . ▁All ▁forces ▁have ▁a ▁direction ▁in ▁which ▁they ▁push , ▁and ▁cent rip etal ▁force ▁is ▁directed ▁towards ▁the ▁center ▁of ▁the ▁circular ▁path . ▁It ▁can ▁be ▁calculated ▁using ▁the ▁following ▁formula : ▁ ▁Where : ▁▁ ▁is ▁the ▁cent rip etal ▁force ▁▁ ▁is ▁the ▁mass ▁of ▁the ▁object ▁▁ ▁is ▁the ▁speed ▁at ▁which ▁the ▁object ▁is ▁moving ▁▁ ▁is ▁the ▁radius ▁of