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Discussion Starter #1
so....are my numbers looking right?

17.5 - 2200Kv x 3.6v = 7920
13.5 - 3300Kv x 3.6v = 11880
10.5 - 4300Kv x 3.6v = 15480
7.5 - 5800Kv x 3.6v = 20880

I usually figure the RPM drop at around 40-45 % under load

so the "LOADED" rpm range would be around @ 55% of the unloaded RPM.

17.5 - 2200Kv x 3.6v = 4350
13.5 - 3300Kv x 3.6v = 6500
10.5 - 4300Kv x 3.6v = 8500
7.5 - 5800Kv x 3.6v = 11500

Now....I want to gear these for the VELODROME

17.5 around40 mph - (3520 ft. per min) = 5378 Axle RPM
13.5 around 48 - (4224 ft. per min) = 6544 Axle RPM
10.5 around 55 - (4840 ft. per min) = 7395 Axle RPM
7.5 around 62 - (5456 ft. per min) = 9336 Axle RPM

The TRACK is 820 ft
The TIRE is 2.50" (.6545 ft.)
1252.9 Tire Rotations Per Lap

17.5 Motor = 4350 Motor RPM / 5378 Axle RPM = OVER DRIVE Ratio .81
13.5 Motor = 6500 Motor RPM / 6544 Axle RPM = OVER DRIVE Ratio .993 (Close enough to 1:1 ratio)
10.5 Motor = 8500 Motor RPM / 7395 Axle RPM = Ratio 1.15
7.5 Motor = 11,500 Motor RPM / 9336 Axle RPM = Ratio 1.23

I have NO idea if these motors on ONE CELL (3.7v) can run this fast or now - that's where the track comes in!!

To Gear the 17.5 @ .81 Overdrive you'd need a 90t PINION and a 72t SPUR

To Gear the 13.5 @ .993, I'd go straight to 1:1 with any 72, 73, 74 tooth w/ pinion/spur adapter.

To Gear the 10.5 @ 1.15 72 Spur w/ 62 Pinion = 1.16, 72/63 = 1.14

To Gear the 7.5 @ 1.23 76/62 (1.225)
 

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Discussion Starter #3
Jon,

I don't have any doubt the 1c battery will be fine, after all we did MOD with ROUND CELLS and 4 cell w/ no real issues.

I just don't know what the motors can top out at w/ ONE cell...and GEARING will be interesting.

I'd like to have answers before things are thrust upon us...
 

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On a one cell 13.5 I calculated my avg rpm based on my lap times and it is around 8500 rpm on the track. so I think your KV calcs are a little low.

John
 

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For 7.5/1s I would gear about .20 rollout points less than your current 17.5/2s gear. For 10.5/1s I would start exactly the same as your 21.5/2s gear. For 13.5/1s, probably add .60 rollout points to your 21.5/2s gear. For 17.5/1s......good luck with that LOL

I would think these would get you close based on what I've seen on both small and larger carpet tracks. I'm guessing you will like lots of ESC timing on the Velo!
 

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For 7.5/1s I would gear about .20 rollout points less than your current 17.5/2s gear. For 10.5/1s I would start exactly the same as your 21.5/2s gear. For 13.5/1s, probably add .60 rollout points to your 21.5/2s gear. For 17.5/1s......good luck with that LOL

I would think these would get you close based on what I've seen on both small and larger carpet tracks. I'm guessing you will like lots of ESC timing on the Velo!
Gets you very,very,close!! up or down a little ,depending on esc.
 

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now for the real question are the cars going to be heavy enough to keep them on the ground......:confused:......even with 2 cell we seen issues with cars lifting.......but you never know could not be an issue in the right class......:thumbsup:
 

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Discussion Starter #9
badoty,

believe me, that's another one of my concerns - but the nice thing about a LIGHT CAR is...if it's TOO LIGHT - it's not hard to add weight!! *(other than mentally)
 

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with the less weight, imo you do not have to spring or use as heavy of damping as we did with the nimh batts or the 2 cell lipo because of the car being that much lighter.... the biggest thing about going 1 cell for the velo, and i dont know about out west, but around here alot of racers follow the tour rules for the most part and most guys already have 1 cell batts so its just a matter of buildiing a car to fit the velo speeds and track... So that way guys already have the equipment to run the velo
 
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