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Gear ratios
 Moderated by: Kevin Gagne Page:  First Page Previous Page  1  2   
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 Posted: Sun Feb 3rd, 2013 07:30 pm
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Rick Chapman
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Mana: 
A gear ratio is not always a final gear ratio. We have used the same ratio on our enduros but always went faster, at the same ratio, with a larger driver. Even on the sprints, I always put the largest driver gear I can... In fact, at Daytona we ran a grer ratio that we never expected to be able to run and we ran second, because of the large driver we ran..
Try an 11 or 12 and see what you think..

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 Posted: Sun Feb 3rd, 2013 09:46 pm
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Scott E
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Steve Welte wrote:
Ha ha this has been discussed for years over on http://www.4cycle.com. There is a difference but it is hard to find. I run every week on an asphalt oval. Times are very consistant. Hundredth's of a second make or break you. I didn't want to believe it either but on the small driver the same kart i can't quite catch on the end of the straight but can get to coming out of the turn, then they pull me by 1/2 kart length on the end of the straight. Go in and change gears to a larger driver say from 14 to 16 but the same ratio. Go back out and I am tapping them or pulling by them at the end of the straight. That lets me get to the inside and loosen them up or go completely under them entering the turn. Once they have broken their momentum they won't catch you coming out of the turn.In two laps you are gone from them. Now That being said on a sprint track I would rather gear for the pull from the turns and all the short sections inbetween where you can make time as long as you don't over rev on the straight. All this doesn't answer the original question which is what I did in the first post. I won't comment any further on this as I've witnessed the never ending battle on this topic. It is probably one of the most argued topics on most forums.

I videoed the 2012 clone kart races at Kartington Raceway (paved, banked tri-oval) and noticed exactly the "momentum effect" Steve describes. Long runs, certain karts did better; short runs, the others did better. I don't know what anyone was running (Driver/Driven) or ratios; what happens and when during the race impacted the results more. So, we need to find a statistical wizard to determine the probabilities of yellow flags and when on a given-number-of-lap race (heat, feature) at a particular track are. Then select your ratio. Unfortunately, the many race car and other sports' teams around the world, gobbled up the statistically gifted individuals. So you have to race by the seat of your pants, gut feelings, psych-out competitors, exaggerate (lie) and the other fun stuff associated with racing.

Sprint kart racing in the 60s, I have experienced 'driver/driven' complexities, but not for the technical reasons described in this thread. I was just a young teen (on a budget), didn't care about the "scientific aspect," and just wanted to have fun and race. What drove my selection process was the tire size I was using (tires lasted most of the season), track configuration (more on this) and how potentially rough the track surface was. Rougher the track for potential sprocket contact, the smaller I went on the driven sprocket and adjusted accordingly.

Sprint Track configuration - Like Steve, I geared more for power out of the corners and shorter straights. I found I made more passes in these areas than I ever did on the "long" straights of the tracks I raced. Any concerns of over revving, I just nursed the throttle. For what it is worth, over the three seasons I raced, I migrated toward smaller sprockets and tires.

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