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Thread: Same Drive ratio - different drive sprocket:axel sprocket combination question

  1. #181
    Quote Originally Posted by rage26 View Post
    A smaller driver weighs less so the motor can spin it up faster = little more punch off the corner. The larger driver once it is spinning will free spin better letting you build momentum through corners easier.
    Quote Originally Posted by rebsfan4 View Post
    One thing I think people overlook or simply don't think about is torque. It's the one constant here. The engine supplies a given torque )for the most part) no matter the gear set. Changing gears sets, up or down changes mass, circumferences, pitch and other things.

    Even then, it still all comes down to being able to maintain momentum, minimize rpm drop so you can run the largest front driver and proper rear gear so you be your fastest on the last 2/3rfs of the straights. If you can do that, the corner speed is already taken care of.
    Thanks for the help.

    Are y'all talking about the same gear ratios or changing gear ratios? Also are y'all talking dirt oval or sprints on pavement? I am just trying to understand things correctly.

    It would seem on an oval the corners would be very similar and the gear ratios would become more critical. On the sprint course we run the layout is constantly changing. Sometimes it is direction, other times it is drastic corner changes. We have some fast corners and some that put you down into the lower RPMs. So being off in one corner may benefit in another. I am getting a handle on gearing. I am usually too low on the gear and need to change to a higher gear. So far I know my chassis setup has been more of an issue than the gearing. I am hopefully closing in on both. My initial gearing picks come down to trying to be on the right size front driver as I figure the front make a bigger difference (per tooth size) and the back is easier to fine tune. A lot of the gearing is in the 3.5-4ish to 1 range. I have been concentrating on chassis more than gearing most of the time anyway.

    Then on an LO206 I hear different ideas about being on the rev limiter anyway. I have found it also depends on what class (slide) you are in.

    Thankfully I don't have to worry about tire prep as that would add a whole 'nother dimension.

    Thanks again.

  2. #182
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    Quote Originally Posted by Mike Clark View Post
    Thanks for the help.

    Are y'all talking about the same gear ratios or changing gear ratios? Also are y'all talking dirt oval or sprints on pavement? I am just trying to understand things correctly.
    One criteria that I would use is the rpm at the end of the straight. For instance; with a 15/60, at 6000 RPM, it calculates (34" tires) out to 48.3 miles per hour at the end of the straight. If you add one tooth to the axle, 15/61, in order to be going the same speed at the end of the straight you have to pick up 105 RPM. Now with the addition of one tooth, you might be faster in the tight stuff, but are you going the same speed at the end of the straight. Nothing worse (in my book anyway) than getting passed at the end of the straight. There's a Sprint track in California with a very long main straight. And I mean long!! At a divisional race the gear that gave me the best lap times, just wasn't right for that long straight. I found that out in the first heat, finishing third. I took two teeth off the axle and won the second and third heats, by a ton. Now there could have been other circumstances involved in that win, I can't say for sure, but that gear ratio change did make a difference. I won the third heat by almost a half a lap against national caliber competition.
    From the desk of Al Nunley 512-630-6215
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  3. #183
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    I was referring to same ratios on dirt oval

  4. #184
    4 Cycle Advanced User rebsfan4's Avatar
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    Quote Originally Posted by Mike Clark View Post
    Thanks for the help.

    Are y'all talking about the same gear ratios or changing gear ratios? Also are y'all talking dirt oval or sprints on pavement? I am just trying to understand things correctly.

    It would seem on an oval the corners would be very similar and the gear ratios would become more critical. On the sprint course we run the layout is constantly changing. Sometimes it is direction, other times it is drastic corner changes. We have some fast corners and some that put you down into the lower RPMs. So being off in one corner may benefit in another. I am getting a handle on gearing. I am usually too low on the gear and need to change to a higher gear. So far I know my chassis setup has been more of an issue than the gearing. I am hopefully closing in on both. My initial gearing picks come down to trying to be on the right size front driver as I figure the front make a bigger difference (per tooth size) and the back is easier to fine tune. A lot of the gearing is in the 3.5-4ish to 1 range. I have been concentrating on chassis more than gearing most of the time anyway.

    Then on an LO206 I hear different ideas about being on the rev limiter anyway. I have found it also depends on what class (slide) you are in.

    Thankfully I don't have to worry about tire prep as that would add a whole 'nother dimension.

    Thanks again.
    The whole ratio is a ratio conversation is about oval racing. Seems to focus more on dirt oval.

    In the end the ratio itself isn't important, so long as it wins.

    When you see these type threads, the conversation (or confusion to some) is always about different gear sets, of the same ratio and whether or not they perform the same. Some "think" they perform the same when others of us know they don't.

    As far as sprint racing, I have virtually no experience with that type racing, so I stay out of places I have no business giving advice.
    Bryan Wesley
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    I tried therapy. They didn't want to listen.

    J & E Karting Services Facebook / Mississippi's Authorized Hoosier Distributor

  5. #185
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    Quote Originally Posted by rebsfan4 View Post
    T
    When you see these type threads, the conversation (or confusion to some) is always about different gear sets, of the same ratio and whether or not they perform the same. Some "think" they perform the same when others of us know they don't.
    What I find interesting about the discussion is; those that "think" they know, can come up with all kinds of reasons and justifications for their thoughts, while those that "know" cannot come up with any ideas on the "why". It's just "that's how it is". I think I'm the only one who has come up with some ideas on the possibilities of "why" bigger gears might give you an advantage.
    From the desk of Al Nunley 512-630-6215
    Comments compliments criticisms and questions always welcome.
    If the data does not support the theory, get a new theory. (Al Nunley)

  6. #186
    Quote Originally Posted by rage26 View Post
    I was referring to same ratios on dirt oval
    Quote Originally Posted by rebsfan4 View Post
    The whole ratio is a ratio conversation is about oval racing. Seems to focus more on dirt oval.

    In the end the ratio itself isn't important, so long as it wins.

    When you see these type threads, the conversation (or confusion to some) is always about different gear sets, of the same ratio and whether or not they perform the same. Some "think" they perform the same when others of us know they don't.

    As far as sprint racing, I have virtually no experience with that type racing, so I stay out of places I have no business giving advice.
    Thanks both for the clarification. Sometimes in communication knowing the context is everything.

    Another aspect of dirt oval vs sprint I see is scaling karts. A lot of sprint guys have told me they will never scale a kart. I can understand not wanting to spend $$$ (?$$$$$$$) on scales but scaling seems like it would be a nice option to have.

    So it seems that the larger gears of the same ratio have some difference that is at least noticeable to a driver. I think mass and the way the chain interacts with the gears are where that is. I have not compared lever lengths to see yet how that works out. I could see where it should be a linear relationship, but might not be if there is a difference in performance.

    I raced bicycles many years ago. Being the motor gives a different perspective in some things. Wheel weight, the number of spokes and how many times they crossed all made a difference. Solid wheels offered good aero, but you had to be in a steady state to have any advantage. Accelerating that flywheel was no fun. Standard crank length was 170 and on track bike it was 165. That was odd & counterintuitive to me because of less mechanical advantage. I had read 165 offered more flexibility for a given gear (track bikes are fixed gear). Seems there is some correlation here.

  7. #187
    4 Cycle Advanced User rebsfan4's Avatar
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    Quote Originally Posted by Mike Clark View Post
    Thanks both for the clarification. Sometimes in communication knowing the context is everything.

    Another aspect of dirt oval vs sprint I see is scaling karts. A lot of sprint guys have told me they will never scale a kart. I can understand not wanting to spend $$$ (?$$$$$$$) on scales but scaling seems like it would be a nice option to have.

    So it seems that the larger gears of the same ratio have some difference that is at least noticeable to a driver. I think mass and the way the chain interacts with the gears are where that is. I have not compared lever lengths to see yet how that works out. I could see where it should be a linear relationship, but might not be if there is a difference in performance.

    I raced bicycles many years ago. Being the motor gives a different perspective in some things. Wheel weight, the number of spokes and how many times they crossed all made a difference. Solid wheels offered good aero, but you had to be in a steady state to have any advantage. Accelerating that flywheel was no fun. Standard crank length was 170 and on track bike it was 165. That was odd & counterintuitive to me because of less mechanical advantage. I had read 165 offered more flexibility for a given gear (track bikes are fixed gear). Seems there is some correlation here.
    I think you have a pretty good grasp of the workings concept. I'd say you were well on your way to figuring out the gear thing.

    Like I said, my knowledge of sprint racing is virtually non-existent. I've only actually rode on a sprint course twice. I would be inclined to think the same way as Al though. In that, I wouldn't want to be passed on the longest straight on the track. I would tend to gear for that section of the track. That's just a guess though.
    Bryan Wesley
    601-503-3502
    I tried therapy. They didn't want to listen.

    J & E Karting Services Facebook / Mississippi's Authorized Hoosier Distributor

  8. #188
    Quote Originally Posted by alvin l nunley View Post
    One criteria that I would use is the rpm at the end of the straight. For instance; with a 15/60, at 6000 RPM, it calculates (34" tires) out to 48.3 miles per hour at the end of the straight. If you add one tooth to the axle, 15/61, in order to be going the same speed at the end of the straight you have to pick up 105 RPM. Now with the addition of one tooth, you might be faster in the tight stuff, but are you going the same speed at the end of the straight. Nothing worse (in my book anyway) than getting passed at the end of the straight. There's a Sprint track in California with a very long main straight. And I mean long!! At a divisional race the gear that gave me the best lap times, just wasn't right for that long straight. I found that out in the first heat, finishing third. I took two teeth off the axle and won the second and third heats, by a ton. Now there could have been other circumstances involved in that win, I can't say for sure, but that gear ratio change did make a difference. I won the third heat by almost a half a lap against national caliber competition.
    Quote Originally Posted by rebsfan4 View Post
    I think you have a pretty good grasp of the workings concept. I'd say you were well on your way to figuring out the gear thing.

    Like I said, my knowledge of sprint racing is virtually non-existent. I've only actually rode on a sprint course twice. I would be inclined to think the same way as Al though. In that, I wouldn't want to be passed on the longest straight on the track. I would tend to gear for that section of the track. That's just a guess though.
    My basic thoughts are faster top end gives a cushion on the straight and forces you to figure out the chassis better for the twisty bits. It is more of a theory since I don't feel like I have handle on the handling yet. I think the fast sections do provide more chances for passes. Thinking about when just spectating it is easier to see the pass coming on the faster sections. The slower sections seem to result in passes when the guy in front makes a mistake. Overall I think being long on gear is better than being short, even though I keep getting it wrong.



    I overhead one of the fast guys at out track telling an upcoming kid "The hardest thing about being in first place is getting there".

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