Jump to content

Featured Replies

  • Author

Stock is 11, so +2 is 13, i may aswell go to probike and get their front sprocket for a fiver

nope, its either a 14 or staying where it is,

  • Moderator

Right you recon your mech theory is pretty good try this.....

Assume engine at max permitted rpm say 7500

Primary ratio (crank to clutch on my 175) 3.227-1 so 7500/3.227 =2324rpm

Now assume top gear 0.8-1 so 2324/.8=2905rpm

Final drive 3.267 so 2905/3.267=889rpm

So the rear wheel at 7500 rpm is doing 889 rpm

Rear wheel at roughly 18inch dia (45cm) circ =PiD 3.14*45=141cm

/100 to 1.41m per rpm so multiply by 889, therefore 889*1.41=1253m per min

so multiply by 60 hence 1253*60 =75209m

so theoretically when my dt is at 7500 rpm it is doing roughly (due to the estimate on the rear wheel)75kph (ironically)

you can use that lot with your own manual to calculate the exact speeds of your bike, and the maximun theoretical speed. Should save any guesswork with the sprockets.

(back when jesus was a boy), but when top gear selected it would die a death,

Now then everthn said so far is spot on about higher gearing. we used to up the front spocket 2 teeth on husky for the Weston Beach Race. [flat oot straights] ,But W,foamy the husky 440 was puttin out 50b.h.p[ still pulled like a train].

Now little storey about gearing :offtopic: while in Weston 1982. WE HIRED A BI-BYCYCLE. [Twin-seater canopy thingy]

Any way" thot we wud tackle a multi-story carpark. ..Let race at the big ramp got half way up [ the fkr was too high grd]

so rolling back the bstd had a fixed wheel-..[ peddals were gona break our legs] so we yanked on the brake[ on the back wheel] :blink: Summersault in reverse*** wrecked the canopy . so we squared it up-- tied the torn material on it , left it at the hire shop door. AND RAN LIKE FUCK. :lol: Willie simpson went on to win the first Weston Beach Race

the next day ... bruises an all . B)

  • Moderator

Right you recon your mech theory is pretty good try this.....

Assume engine at max permitted rpm say 7500

Primary ratio (crank to clutch on my 175) 3.227-1 so 7500/3.227 =2324rpm

Now assume top gear 0.8-1 so 2324/.8=2905rpm

Final drive 3.267 so 2905/3.267=889rpm

So the rear wheel at 7500 rpm is doing 889 rpm

Rear wheel at roughly 18inch dia (45cm) circ =PiD 3.14*45=141cm

/100 to 1.41m per rpm so multiply by 889, therefore 889*1.41=1253m per min

so multiply by 60 hence 1253*60 =75209m

so theoretically when my dt is at 7500 rpm it is doing roughly (due to the estimate on the rear wheel)75kph (ironically)

you can use that lot with your own manual to calculate the exact speeds of your bike, and the maximun theoretical speed. Should save any guesswork with the sprockets.

Damn....I was just gonna say that :lol:

(back when jesus was a boy), but when top gear selected it would die a death,

Now then everthn said so far is spot on about higher gearing. we used to up the front spocket 2 teeth on husky for the Weston Beach Race. [flat oot straights] ,But W,foamy the husky 440 was puttin out 50b.h.p[ still pulled like a train].

Now little storey about gearing :offtopic: while in Weston 1982. WE HIRED A BI-BYCYCLE. [Twin-seater canopy thingy]

Any way" thot we wud tackle a multi-story carpark. ..Let race at the big ramp got half way up [ the fkr was too high grd]

so rolling back the bstd had a fixed wheel-..[ peddals were gona break our legs] so we yanked on the brake[ on the back wheel] :blink: Summersault in reverse*** wrecked the canopy . so we squared it up-- tied the torn material on it , left it at the hire shop door. AND RAN LIKE FUCK. :lol: Willie simpson went on to win the first Weston Beach Race

the next day ... bruises an all . B)

Should o had ye IRN BRU.

  • Author

good old irn bru :)

for the sake of a few quid i will go up to 14 on the front and see how i get on, but i was riding with a mate and his ped speedo was showing 52 when i passed him :P

  • Moderator

good old irn bru :)

for the sake of a few quid i will go up to 14 on the front and see how i get on, but i was riding with a mate and his ped speedo was showing 52 when i passed him :P

:lol::lol:

There is nothing more optomistic than a ped speedo, seriously WF do the math and you will know how fast you can go, if you jury rigged a rev counter you would be able to get the bikes speed almost exactly. An rd 50 of the same vintage could donate all the parts for a mechanical one, they are just not fitted on the DT. All the machining has been done.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...