Front sprocket
 

Hey just a quick question. I have a Roketa db-07 im trying to get some more top end out of its taken apart right now I already installed a 45 tooth rear sprocket but the front sprocket I got with my order (ebay) was a 15 same as what I had supposed to be a 17. Will the 17 front sprocket make a big enough difference or do you think the 15 will do about the same? Not wanting to go to the trouble of sending it back for an exchange if it wouldnt be worth the wait. Thanx

45/15=3.0 "3.0 is your final drive using those two sprokets" "3 turns of front per every 1 rear sprocket revolution"
45/17=2.64 "17 tooth sproket"

3.0-2.64= .36 the amount of ratio you gain by using the 2.64 ratio

.36/3.0=12% increase "or 3.0-2.64/3.0=.12"

12% more top end, more fuel milage 12% lower engine speed..... keep in mind these are only numbers. the wind you are fighting at the upper speeds will still slow you down. The higher gear ration "2.64" will rob you of 12% of the power you would normally have.

IMO I am going to wear the stockers out and invest in other areas, such as tires, and a dumb driver force field. Had a soccer mom incident today, thoes H3 hummers really are intimidating when you get close to them. :x

Now that was a hell of an answer lol. Yeah we could all use the force field. Thanx man

no prob save this to your favs if you need the formulas in the future......BECAUSE KNOWLEDGE IS POWER!!!!! :D

What type of speed do you plan to travel at? That ratio may not be bad if you don't plan to go much over 60mph.

The 17t sprocket will give you about 2.67 ratio.

Allen

Just want to be able to get on the highway and not get run over. Maybe even enough power to pass someone. What the best ratio?

The lifan seem to do well with a 17/45 combo.

Give the 15 a try and see if it works for you.

The Roketa may have alittle taller gearing.

Allen

katoranger, I am not one to really quarrel but how do you divide 45 into 17 and get 2.67? Is there something I am not accounting for? I ask this because my calc says 2.6470588 revolutions of the front sprocket for a single revolution of the rear sprocket.

Please understand I am not questioning your knowledge but I am extreamly anal about any of my calculations and want to get it right next time if I am wrong this time.

Ok thanx ill try it and report back.

You're right. I missed the 4 after the 6. On my bike the 17/45 works out to 70mph at 8K rpm.

Allen

17/44
 

I just replaced the rear on my Shineray. I put on a 44 tooth rear and it came with a 17 tooth front. With my new 17/44 setup I can run 55mph with a little room to go. It's really not a bad setup. Much better that the original 17/56, where first gear is almost useless. Never ran the 15 tooth front so I cannot comment on that.

Oh I did. At 55 the bike was screaming for mercy.