arcticflipper Posted November 29, 2005 Share Posted November 29, 2005 Loking at a xls spreadsheet that I got off this board, but then nothing ever works as it is stated on paper... I've seen a couple of guys running 18 front sprockets, with what size rear? What in the real world will I loose if I run a 18 front with a 42 rear? Will I have absolutely no power for pull off? and will i need to run down a mine shaft to actually get the full potential that the sprockets will be able to give me in speed? Or is this acceptable? One tooth in front = 3 at the rear if I remember correctly, but I can't remember how this influence fuel economy According to the paper work this setup will give me the following figures: RPM mph Gear 10 000 190.0 6 10 800 205.2 6 10 000 148.5 4 10 000 169.7 5 etc etc Quote Link to comment Share on other sites More sharing options...
The Krypt Keeper Posted November 29, 2005 Share Posted November 29, 2005 gearing is simple.. The bike geared stock is 17F 45R I believe 45 divided by 17 = 2.647 Which means the front turns 2.647 times compared the the rears one full turn.. you increase the front to 18 and keep the 45R you will have slower acceleration but may increase top end if you have enough torque to push you. (thats a whole different subject) If go down to a 16 in front you will gain quicker acceleration but sacrifice top end.. not much probably up to 160 or so. or you can leave the front stock at 17 and adjust the rear buy adding or subtracting teeth. since you can't get 2.647 teeth simple round up to 3 teeth or maybe try just 2 teeth to see if you like the results. If you add 3 teeth in the back it does the same taking away one tooth in the front and take away 3 teeth its like adding a tooth in front. Most people go with the front as its cheaper... either way you will have to get a speedo healer or buy a gps if you want accurate speed. smaller in front will make your bike run at higher RPMS same as taking 3 away in the rear and vice versa Quote Link to comment Share on other sites More sharing options...
devilisht2003 Posted November 29, 2005 Share Posted November 29, 2005 glad someone is using my excel sheet...hope it helps Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted November 29, 2005 Share Posted November 29, 2005 Probably, but not sure if what he is asking is if there an advantage or disadvantage to the same gear ratio but different tooth counts. 17/45=2.64706 18/48=2.6666 16/43=2.6875 I have been wondering if there is a leverage advantage to having a larger front. This of course requires a larger rear and it gets into a space problem,,,,but having run from 14 to 17 front with the same gear ratio in the rear I have convinced myself that I want the largest front that I can run and to figure what rear limits I have. For info I am on a 16/58 with a 24 inch tire now and have a 17/61 to try soon. The thing is torque and leverage. If the motor has the torque to turn the leverage of a larger front it will acelerate harder, at the same gear ratio. Some thing like that. Feels much different at the seat as far as I can tell. Will run on the track soon and see if that is right. Some of the drag racers I know do this. Makes for some large rear sprokets. If this is not what you were talking about well (nevermind) Stan Quote Link to comment Share on other sites More sharing options...
shovelstrokeed Posted November 30, 2005 Share Posted November 30, 2005 The larger front makes for a more efficient setup for a given gear ratio as chain friction is greatly reduced, as is chain wear. Gearing is more or less gearing. Shorter or numerically larger ratios will give better acceleration, taller ratios may give higher top speed. Torque has little to do with it, it's about HP at that point. Quote Link to comment Share on other sites More sharing options...
beondwacko Posted November 30, 2005 Share Posted November 30, 2005 Gearing is more or less gearing. Shorter or numerically larger ratios will give better acceleration, taller ratios may give higher top speed. Torque has little to do with it, it's about HP at that point. Â Exactly ! Torque = Acceleration Horsepower = Top speed Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted November 30, 2005 Share Posted November 30, 2005 Leverage has nothing to do with torque???? trick question? the bird has better torque than horsepower? aceleration than top speed? bigger front, better aceleration and top speed, same ratio with high torque engine. Just a question that applies to bird only. load that motor. Quote Link to comment Share on other sites More sharing options...
arcticflipper Posted November 30, 2005 Author Share Posted November 30, 2005 glad someone is using my excel sheet...hope it helps Thanks a lot, it's spot on with the gps units and speedohealer installed. Quote Link to comment Share on other sites More sharing options...
demon Posted December 1, 2005 Share Posted December 1, 2005 I have been wondering if there is a leverage advantage to having a larger front. This of course requires a larger rear and it gets into a space problem,,,,but having run from 14 to 17 front with the same gear ratio in the rear I have convinced myself that I want the largest front that I can run and to figure what rear limits I have. For info I am on a 16/58 with a 24 inch tire now and have a 17/61 to try soon. The thing is torque and leverage. If the motor has the torque to turn the leverage of a larger front it will acelerate harder, at the same gear ratio. If you put a larger sprocket on the front and an even larger one on the rear to get the same gearing, the "torque" advantage you speak about will negate itself. It would take more torque to spin a larger front and less to spin a larger rear, think of where the power is coming from and where it's going. The overall gearing would be the same so the RPMs at any speed would be the same. You're adding mass that you have to accelerate both in the chain and the sprockets. You might get less resistance in the bend of the chain around the front sprocket, but the added weight would ofset this as well. Quote Link to comment Share on other sites More sharing options...
bpg Posted December 19, 2005 Share Posted December 19, 2005 out of curiosity, what is RPM with stock gearing at 65, 75, 85 mph? Quote Link to comment Share on other sites More sharing options...
Redbird Posted December 19, 2005 Share Posted December 19, 2005 out of curiosity, what is RPM with stock gearing at 65, 75, 85 mph? You'd be in the 4-5k range at those speeds, assuming top gear. Quote Link to comment Share on other sites More sharing options...
feelergaugephil Posted January 2, 2006 Share Posted January 2, 2006 The guy that bought all my XX parts (including the engine) runs it on 17 Front and 37 rear, he claims that it does 240mph (not digital speedo) The rear sprocket was made by a unknown Co. Quote Link to comment Share on other sites More sharing options...
Red J Posted January 3, 2006 Share Posted January 3, 2006 The guy that bought all my XX parts (including the engine) runs it on 17 Front and 37 rear, he claims that it does 240mph (not digital speedo)The rear sprocket was made by a unknown Co. Maybe on paper, but it doesn't go that fast without a turbo, or a massive shot of nitrous. Quote Link to comment Share on other sites More sharing options...
gharknes Posted January 3, 2006 Share Posted January 3, 2006 torque is the ability for the engine to turn the wheel at any given rev, hp is calculated from torque and revs and load. Quote Link to comment Share on other sites More sharing options...
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