well bro there are 3 stages of rev reduction in bike ... 1st as primery reduction [3.35 for ex] ,then we have actual gear ratio i.e. [3.076 for 1st gear and .937 for 5th ] ..then comes secondary reduction i.e sprockets [42/15=2.8] ..

over all 8000 rpm of crank reduces to

8000/(3.35*.937*2.8) = 910.222 .. revs at rear wheel ... which tanslates to around 111 kmph for our example bike @5th and 34 kmph @1st gear ...

now we make changes to sprocketing .. we add 1T F for top speed... so now

SR = 2.625
PR = 3.35
GR = 3.076 ,0.937

achieved speeds are ..
1st = 36 kmph
2nd = 119 kmph


top speed increases coz effective rev reduction is less i.e. 970.903 rev at rear wheel which translate to 119 kmph ..

so actually when we increased the teeth at F sprocket we actually increases the radius of sprocket at front .. increased radius means to achieve same speed engine now have to pull harder .. under stand this by the following folrmula

torque = force x radius

or

fOr constant torque from engine [i.e.] this changes to

F x R = constant ..

F = ( constant ) / R

this F cause ur rear sprcket to rotate [transmittion via chain ] ... getting the point ..

increase in radius causes the same available torque [and F for rear sprocket] at any rev to produce greater revs witha helpof larger dia front sprocket .. but as soons as peak torque is achieved even a more larger dia F sprocket wont give u good top speed COZ U DONT HAVE ANY MORE TORQUE AT THOSE REV RANGE OR FOR THAT LOAD AT REAR .. F's value go for a toss and it reduces to something that can not rotate rar sprocket for more revs even at hger rev of crank ...

this is written assuming that only front sprocket is changed for top end .. had it been a reduction in T at rear sprocket same torque force radius analogy will then changes slightly coz variable involved are now different ..

have a pic ..

Thanks for the replies Mr.viv.nomad and Mr.R-series.

Well! before i encounter this thread i had played a little bit with my bike. Mine is p200. Which has a stock set up of 14/38. After seeing the new p220dtsi with 14/36. I swapped It. The changes that was noticeable was lesser pull in lower RPMs. The feel of pulling punch which was in the revv band less than 6k RPM has changed its position upwards. It used to accelerate quicker between 6k RPM to 9k RPM. Before the sprocket change when it was in stock condition the quickness lied before 6k RPM. When dragged in all the gears it used to reach its top speed in lesser time with 220's sprocket setup but couldnt find much noticeable difference in top speed. Bike used to die when ridden normally i mean in lesser RPMs.

guys, help me to de sprocket my p150 ug3, which sprocket is best to play with front or rear, which one damages my engine less[if any] and which costs less so that i can try diff combinations. my req is to get more top end speed not much bothered abt drop in torque..

"Cruise at a lower rpm" for Shogun

Guys,

My priority is "cruise at a lower rpm" in my Shogun . I have already replaced the original 13/44 with 13/39 from the Fiero. Also, my bike runs on 3.25 x 16 rear tyre. So the sprocketing kind-off compensated this reduction in tyre size and now I am back to same stock scenario .

Now I would like to go ahead with the RX135 16/34 sprocket combination . I know this would be a really high gearing, but what are the consequences here? Also. is there any other "direct" fit GB sprockets in 15 or 16 sizes for the Shogun ?

Thanks in advance.
Suresh

Am not sure if they are direct fit, but if u r sure if RX135 front will fit then just plonk the GB and let the rear be 39 !! Increasing front by 1t is almost equal to decreasing rear by 3t.!! So u are putting 16t then rear is straight down to 14t/33t i.e 16/39 (approx). I can't even imagine 16/34 !!

Just came across & Sharing this awesome site of Bikes RPM, Sprocket, calculating Top Speed, Torque,.. etc..
Seriously a wonderful & useful WebSite
Gearing Commander: Motorcycle Gear Ratio Calculator for Sprockets RPM Speed Chain

Is there any #428 37T sprocket available friends.. which bike has it!!... ?

no need to be with direct matching holes.

You can choose the rear sprocket of Pulsar 180 UG3 which has 43 teeth. It will help very slightly.

Also, the Pulsar 180 UG2's rear sprocket has 42 teeth, but I'm not 100% sure it will fit directly.
So, please check fitting yourself. (Don't believe the Bajaj mechanics, they always say it doesn't fit)

I have an Apache 180. I have changed my rear tyre from stock 110/80 to 100/80 (Zapper S). With the stock tyre my bike used to reach 53-54 at 4k rpm 5th gear. Now after the tyre change it reaches 51-52 at the same. I want to increase my top end so that my bike can reach 60 at 4k. So what sprocketing mods should i do?
The true top end of my stock bike is something around 124 kmph as stated by the biking magazines. I would be good if i can reach something around 130 or a little more with it now with the 100/80 rear.

you can either go for reducing your rear sprocket teeth by 2 teeth or by increasing front teeth by 1.. it wud be better if u post ur stock sprockets size . Even after doing this i guess u will some where reach near the stock speed as u have already went for 100/80 tyre..which shld have been reduced ur top end by now.. altering sprockets heavily can damage crank...

I can revert back to the stock tyre size if needed. My stock sprockets are 14/46. The RTR160 has a 44T rear. I will have to see if thats a direct fit. How much approximate speed gain can i expect in each rpm after moving down 2 teeth on my rear?

if they r direct fit u will get a 5-7 kmph difference in each gear i think... though i am not sure of the exact speed diff u get.. do post the diff once u have done the changes

Ok. And can you tell me which 15T front sprocket can fit my bike?

not much knowledge on TVS.. bikes.. i think tvs service guys can help you.... better ask our sprocket guru "Samarth 619"

i will be changing my bike's stock sprocket kit with that of th p200's.. will click snaps and let u know of the perfomance.

my bike is a pulsar 180 ug2 2006 model. done 33000. What else is needed to be replaced? like clutch or anything?? havent replaced any parts(engine) till now except brake pads etc..