Fixed gear gear ratio calculator

To find the output torque and speed of a gear reducer, use these. gear ratio formulas: Ouput Torque = Input Torque x Ratio of Gear Reduction. Torque is measured in Inch Pounds. Output Speed = Input Speed / Ratio of Gear Reduction. Example: A gear reducer with 1000 in/lbs of input torque, an input. speed of 2000 RPM, and a reduction ratio of 3.5 ...

Fixed gear gear ratio calculator. Apr 7, 2022 ... What is the gear ratio? Why should you use a Gear Ratio Calculator? How can a Gear Ratio Calculator help you in your everyday life?

A Gear Ratio Calculator is a specialized tool used to determine the gear ratio of a mechanical system, such as a gearbox, transmission, or drivetrain. Gear ratios play a crucial role in the functioning of various machines and vehicles, impacting factors like speed, torque, and mechanical advantage. Here, we’ll explore the purpose, features ...

Gear Ratio. Simply put, your gear ratio compares the number of teeth in your front chainring to the number of teeth in your rear chainring. For example, at 34-tooth …RPM = Revolutions per Minute. All Calculators require a Premium Membership. Illustration. Equation and Calculator for Gear Ratio. Figure 1. F = 1 + C / B. Gear Ratio RPM Calculator Case 1. Figure 2. F = 1 - C / B.Bottom gear / Top gear = Gear Ratio. Example 43/27 = 1.59 ratio – Note that gears are generally discussed with mentioning the top gear first like “Twenty. seven, fourty three” Gears are displayed in text as 27:43 with a ” : ” to separate the values. More examples, 44 / 24 = 1.83 ratio and then written and spoken as 24:44Compare two different bicycle drivetrains side-by-side. Supports any number of chainrings and cogs, as well as many popular internally-geared hubs. Results can be displayed as gear inches, metres development, or Sheldon Brown's gain ratios.The following instructions aim to assist you in effectively using our gear ratios calculator, ensuring a more seamless and informed experience. Count the number of teeth on the front cog of your bicycle, and select this value in the picker labeled chainring. Do the same on your rear cog for the picker labeled sprocket.

If you're using a Schlumpf Drive plus an internal-gear rear hub you should enter the actual number of teeth of the front chainring for the first chainring, and this number of teeth times the Schlumpf ratio for the second chainring. The ratios are 0.40 for the Mountain Drive, 1.65 for the Speed Drive, and 2.50 for the High Speed Drive.In general, you can calculate rotational speed using the following gear ratio equation: S 1 • T 1 = S 2 • T 2, where. S 1 is the speed of the driver wheel and T 1 is the number of teeth on that wheel. S 2 and T 2 are the speed and tooth count of the driven wheel. If you're designing a gear system, you will find a gear ratio chart handy.In this video we'll talk about how to calculate fixed gear ratios, how those numbers translate to your ride feel and speed, and how to choose the best gear r...If you’re new to the world of investing, then a return on investment (ROI) calculator can be a helpful tool to use along your journey. To simplify the process of figuring out this ...How to calculate the gear ratio in a planetary gear set where one member is stationary

Input Your Values: Commence by accurately entering the values into their respective fields on the calculator form. Click “Calculate Gear Ratio”: Once all the values have been inputted, proceed to click the “Calculate Gear Ratio” button. Interpreting the Result: The calculator will promptly generate your calculated gear ratio ... Calculate. [/fstyle] Formula: Unlock the mystery of gears with this formula that’s smoother than a well-oiled cog: Gear Ratio = Number of Teeth on Driven Gear / Number of Teeth on Driving Gear. Ready to dive into the fascinating world of gear ratios? Let’s gear up and go! Tableau des skid patchs. Le ratio correspond au nombre de dents du pédalier divisé par le nombre de dents du pignon, plus ce chiffre est élevé plus le pédalage deviendra difficile au démarrage et en côte mais plus il sera possible de monter en vitesse. A l’inverse un ratio bas permettra un démarrage facile, l’absorption de ...2.44. 44. 19. 2.32. 44. 20. 2.20. Understanding gear ratios is crucial because this ratio determines how hard or easy it is to pedal, how much speed you can generate, and what kind of terrain your bike is suited for. As such, manipulating your gear ratio is key to customizing your fixed gear ride to fit your specific needs and cycling goals.If you’re new to the world of investing, then a return on investment (ROI) calculator can be a helpful tool to use along your journey. To simplify the process of figuring out this ...

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So, one revolution of the pedals at a gear ratio of 39/28 will take you 3.23 meters (2.31 x 1.4). If you multiply this figure by your cadence – let’s say 100 rpm in this case – you can calculate the speed. In this example, the bike would be traveling at 19.4 km/h (3.23 m x 100 rpm x 60 minutes). Note that other factors affecting speed ...Gear Ratio. Count the number of teeth on the front cog of your bicycle, and select this value in the picker labeled chainring. Then do the same on your rear cog for the picker labeled sprocket. Gear Inches. Following on the steps to calculate the gear ratio, measure in millimeters the thickness of your rear tire across its tread when inflated ...Houseman Autosport 6564 Decker Drive London, Ontario, CANADA N6P 1J5. P: 519-652-3030 (Eastern Time) Send Us a MessageFixed gear bikes are commonly sold with a 46 tooth chainring and 16 tooth sprocket giving a gear ratio of 46:16. Fast enough on the flats, but not too hard on the hills. It’s equivalent to 52:18, which might be the larger chainring and 4th position sprocket on a multi-speed bike. This is a simplified explanation and the exact details vary ...RPM. The ratio of a ring and pinion gear set is simply the number of ring gear teeth divided by the number of pinion gear teeth. To use the calculator, count the teeth on each gear and enter them in the appropriate box. Press the Solve button and the ratio appears below. The results can be used in our Transmission Ratio RPM Calculator and RPM ...

Example Calculation. Suppose you’re upgrading from a 30-inch tire to a 35-inch tire, and your vehicle’s current gear ratio is 4.0:1. Using the formula: Adjusted Gear Ratio=4.0× (3530)=4.0×1.1667=4.667Adjusted Gear Ratio=4.0 ×(3035)=4.0×1.1667=4.667. This means with the new, larger tires, to maintain performance, you would ideally need a ...Here is a list of the top five fixed-gear bike gearing options for hills, ranked by their difficulty: 23/19 Best fixed gear ratio for hills. 22-11 Best fixed gear ratio for steep hills. 21-13 Best fixed gear ratio for hilly terrain. 20-15 Best fixed gear ratio for very hilly terrain. 19-17 Best fixed gear ratio for seriously hilly.4. If you’ve trialled gears in the past, analyse those gear ratio’s to work out what was more successful for you in terms of a) efficiency over time and b) power output over time. 5. Make sure you’re completing both gym and bike exercises to improve your strength, power and speed – but more importantly, make sure you these exercises are ... 4. Input the center distance between the pinion and the gear. 5. If needed, also input the gear cutting tool's tip rounding radius coefficient. 6. Input the number of teeth of the pinion and the gear. 7. Enter the precision grades of the two gears as well as absence or existence of tooth form correction (s). 8. Divide the number of teeth on each "driven" gear by the number of teeth on the "drive" gear for each interlocking set of gears to calculate the intermediate gear ratios. In our example, the intermediate gear ratios are 20/7 = 2.9 and 30/20 = 1.5. Note that neither of these are equal to the gear ratio for the entire train, 4.3.For a fixed ring gear, the transmission ratio i r can be calculated as follows using the fixed carrier transmission ratio i 0: \begin{align} &\boxed{i_r = 1-i_0}\\[5px] \end{align} Even the fundamental equation for planetary gears (\ref{pl}) can be expressed by the fixed carrier transmission ratio i 0: \begin{align}Step-by-Step Guide to Using Our Bike Gear Ratio Calculator. Follow these simple steps to determine your optimal gear ratios using our bike gear ratio calculator: Select the Min and Max number of teeth on your bike’s chainrings. Select the the Min and Max number of teeth on your bike’s Cog. Click “Calculate” to generate a list of gear ...Typical Epicyclic Gear Arrangement. There are three configurations possible with this epicylic gear. Star where the planet carrier arm is fixed and the sun and annulus ring gear rotate. Fixed frame assembly Input and output shaft rotate in opposite directions Ratios up to 10:1 (approx)-- (Reduction or increase depending on drive direction.)Step-by-Step Guide to Using Our Bike Gear Ratio Calculator. Follow these simple steps to determine your optimal gear ratios using our bike gear ratio calculator: Select the Min and Max number of teeth on your bike’s chainrings. Select the the Min and Max number of teeth on your bike’s Cog. Click “Calculate” to generate a list of gear ...

How to Calculate Ratios. In order to keep numbers in direct relation you should first divide or multiply, which depends on your task, them in the ratio. Therefore, a ratio of 8/6 is an equivalent ratio of 4/3: in that particular ratio calculation, you should just multiply 4, as well as 3, by 2. You may also want to try our Aspect Ratio Calculator.

Use this calculator to determine your gear ratio and vehicle’s speed in any gear and any engine RPM for best performance. Scroll through the list of popular transmissions to find yours. Or, change input variables (engine RPM, axle gear ratio and tire height) to determine vehicle speed in each forward gear. For the Tire Height field, enter ...Select gear sizes below and hit CALCULATE to see ratios for all three cases. Sun gear: Select 8 teeth 12 teeth 14 teeth 16 teeth 20 teeth 24 teeth 28 teeth 36 teeth 40 teeth 56 teeth 60 teeth Ring gear: Select 24 teeth (inside of a 56t turntable) 48 teeth (Power Miners wheel) 60 teeth (small 4-piece ring gear) 140 teeth (large 4-piece ring gear) 168 teeth (Hailfire …The gear ratio is calculated by dividing the number of teeth on the front chainring by the number of teeth on the rear sprocket. For example, if the front chainring has 50 teeth and the rear sprocket has 25 teeth, the gear ratio would be 2:1. Understanding bicycle gear ratios is important for any cyclist.How to use. Open the Calculator: Look for a white box labeled “Bike Size Calculator” on the website. Use a Preset: Select “Man (Avg)” or “Woman (Avg)” to auto-fill average measurements. Input Measurements: If the presets don’t apply, manually enter your height, inseam, and arm length in inches. Click “Calculate”: The tool will ...To determine the gear ratio of a particular gear combination, all you need to do is divide the number of teeth on the front chainring by the number of teeth on the rear cassette. For example, if your bike has a front chainring with 50 teeth and a rear cassette with 11 teeth, the gear ratio would be: 50 / 11 = 4.55.27-01-2006 – V1.03 – Increased the range of gears 19-11-2002 – V1.02 – Fixed pulldowns so they don’t disappear off the screen. Gear Chart 23-02-2010 – Improved usability, better formatting and highlighting. Mouse over highlights the cell to give you a summary. Tioga Specific gear chart and calculator Finally you can work out the ...Understanding the Calculation. The gear ratio is calculated by dividing the number of teeth on the driving gear by the number of teeth on the driven gear. This ratio is crucial in …The total is the gear ratio for that gear setting. Divide the number of teeth on the driving member by the sum of the sun gear and ring gear teeth on the planetary gear for a system set in overdrive with the carrier as the input. The resulting number is the gear ratio for that transmission setting. Count the number of teeth on the driven gear ...

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The bicycle gear ratios calculator is a tool that can be used to find the ideal gearing for your bike, based on your preferred cadence and the type of riding you will be doing. To use the calculator, you will need to know the following information: The size of your bike wheel; The width of your tires;Derailer Gear/Internal-Gear Calculator. Translation of this article: French. German. by Sheldon "Gain Ratio" Brown. You need to enter data for at least one chainring, and at …Also calculates metres of development and (optionally) speed or cadence, and gain ratio. Bicycle 'gear inches' is equivalent to the diameter of the drive wheel on a direct-drive bicycle with pedals fixed to the wheel, or when the number of teeth on the chainring and the sprocket are the same: a 1 to 1 drive. Gear inches is used mostly for ...Simply select a vehicle, and it will prefill the fields in the calculator (Optional) Speed: Choose between mph or km/h. Tyre Size: Enter your tyre size or Outer Diameter (inches). Max rpm: Enter your maximum engine rpm limit. Final Ratio: Enter your final drive ratio. Gear Ratio: Enter the gear ratio for each gear.Calculate Ratio: Instantaneous computation of the gear ratio, achieved by dividing the number of teeth on the driven gear by those on the driving gear. Display Output: The calculated gear ratio is presented numerically, typically in decimal form or as a simplified fraction.This mechanism is used for reduction / speed-up gear. In the picture above, meshing is the sun gear A -> the planetary gear B -> the planetary gear C (coupled with the gear B) -> the sun gear D (concentric to but not coupled with the gear B) and the gear A is fixed, while the arm E rotates. To obtain the speed ratio, firstly fix the arm E and ...By EngineerExcel. Planetary gear systems are a type of gear train configuration where a central gear, called the sun, meshes with and is surrounded by planet gears, which in turn mesh with an outermost gear called the ring gear. Due to their advantages of high efficiency, compactness, and high power-to-weight ratios, they are widely used in ...GEAR CALCULATOR. APPLY YOUR DETAILS IN THE FIELDS BELOW TO VIEW THE MPH. X Remove. Top Gear: Bottom Gear: Engine RPM: Gear Ratio: Constant: Belt …Remember, if you want to calculate the ratio for a gearing combination that’s not included in these charts, simply divide the number of teeth on the chainring by the …(Chainring Teeth / Cog Teeth) x Rear Wheel Diameter (wheel & tire) = gear inches. Gear-inches are useful because you’re given a numerical value for your specific setup compared to all others. Knowing your bike’s gear-inch measurement allows you to make better decisions when customizing your gearing. Gear Ratio.Calculate your bike gear ratio for your fixed gear bike. Use our free calculator now. How to Use the Bicycle Gear Inches Calculator. Using the Bicycle Gear Inches Calculator is simple and straightforward. Here’s how: Step 1: Select the Rim Size. Choose the size of your bike’s rim from the drop-down menu. ….

Strange Engineering Ring and Pinion Gear Ratio Calculator. Calculate the Gear Ratio Needed to run a certain 1/4 mile. Also solve for RPM, Tire Size and MPH. FixMeUp! is software that helps you figure out what gears will fit on your fixed-gear or single-speed bike. It's particularly useful for bike frames with vertical dropouts, because on those frames you can't just move the rear wheel to take up slack in the chain. The gear ratio formula for two meshing gears is simple and intuitive, while the gear ratio formula for the planetary mechanism is not. In this tutorial, we ...Wheel circumference = (622 + 23 × 2) × pi = 2098.58 mm. The gear ratio is the number of chainring divided by the cassette. The rest is a matter of unit conversion. To get a result in km/h, multiply the formula by 60 and divide by 1,000,000. To get a result in mph, divide the km/h by 1.609. 2. Break down the event/discipline and work out which energy system you will mostly be utilising and what’s achievable in terms of an average cadence over the total time of the event. 3. For shorter, more sprint type events, run a few trials on different gear ratio’s to work out your maximum power output and drop off over 30 seconds. 4. Use this calculator to determine your gear ratio and vehicle’s speed in any gear and any engine RPM for best performance. Scroll through the list of popular transmissions to find yours. Or, change input variables (engine RPM, axle gear ratio and tire height) to determine vehicle speed in each forward gear. For the Tire Height field, enter ... The Gear Ratio Calculator can be an excellent tool for budding robotic engineers and students to experiment with these principles. Using the Gear Ratio Calculator is straightforward. Simply input the number of teeth for the driving (input) gear and the driven (output) gear, and the calculator instantly provides you with the gear ratio. Gear Ratios. BikeCalc offers a wide range of gear sizes for BMX, CX, MTB, road bikes, track bikes, ... BikeCalc allows fixed gear cyclists who skid stop to extend the lifespan of their rear tire by increasing the number of patches. ... It's the only gear calculator I trust with the correct maths. Thank you for keeping it alive all these years!"Le "Fantastic Fixed Gear Calculator" vous est gentillement offert par l'équide de SURPLACE, ouai ouai on est sympa. Toutes les données relatives aux circonférences de pneu proviennent du fantastique site de Sheldon Brown. Merci à lajalousie pour les corrections apportées au calcul des skid patchs ambidextres Fixed gear gear ratio calculator, Transmission Gear Ratio Equation and Calculator. Mechanics and Machines Calculations Menu. The following equations and calculators will estimate the resultant vehicle speed at a known engine rpm for a manual transmission with up to six forward gears. To determine the distance the vehicle will travel for one revolution of the engine by dividing the …, Fig. 6.4 Gear separated in two parts. (Fixed) For helical gears or worm gears, there is a way to adjust the phase relationships between the tooth position of each meshed gear by moving one of the paired gears (1) in an axial direction. Fig. 6.5 shows the basis. Fig. 6.5 Backlash Adjustment of Helical Gear (d) Tapered gears (Spur gear and tapered gear racks) …, 2.44. 44. 19. 2.32. 44. 20. 2.20. Understanding gear ratios is crucial because this ratio determines how hard or easy it is to pedal, how much speed you can generate, and what kind of terrain your bike is suited for. As such, manipulating your gear ratio is key to customizing your fixed gear ride to fit your specific needs and cycling goals., For a fixed ring gear, the transmission ratio i r can be calculated as follows using the fixed carrier transmission ratio i 0: \begin{align} &\boxed{i_r = 1-i_0}\\[5px] \end{align} Even the fundamental equation for planetary gears (\ref{pl}) can be expressed by the fixed carrier transmission ratio i 0: \begin{align}, Gearing Analyzer with Shift Tracer. Check Compare and enter alternate Tire Diameter or Diff Ratio. Speedometer will display a second needle for the comparison. Edit gear ratios, or enter (and save) multiple ratio sets, then click Compare Ratios to display multiple graphs and compare ratios. Printable Full Scale Degree Wheels Dial in your cam., The Fixed Gear Bike Ratio Calculator provides you with a clear and easily understandable gear ratio value. This numerical output is crucial for cyclists as it offers insights into how your bike performs under diverse conditions., Dec 28, 2021 ... magic ratio calculator: https ... Single Speed Gear ratio again. Ride4life ... How to Choose the Fixed/Singlespeed Gearing Best for YOU | Fixed Gear ..., However, finding the optimal gear ratio may not always be that easy and you’ll definitely need some tools. To help you with that, I’ve created a go-kart gear ratio chart and speed calculator. I’ve also included guides and tips, so that you can find the optimal gear ratio for your go-kart. Gear Ratio and Speed Calculator ; Gear Ratio Chart, The formula is (wheel diameter + tyre diameter) × π × gear ratio; GI: Gear Inches also known as Effective Diameter, describes gear ratios in terms of the diameter of an equivalent directly driven wheel if the pedals were fixed to that wheel (like a Penny Farthing). The formula to calculate it is (wheel + tyre diameter in inches) × ..., Belts offer flexibility in that the shafts do not need to be right next to one another, and gears are more commonly used in high-load applications. Figure 11.2.1 11.2. 1: Belts and pulleys are often used to transmit motion and torque from one shaft to another. Figure 11.2.2 11.2. 2: Gears are another common way of transmitting motion and torque ..., Gear Ratio Calculator. Ring-and-pinion selection made easy! Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Just type in your info (example: 5000 RPM), press calculate, and you’ll get the …, Bottom gear / Top gear = Gear Ratio. Example 43/27 = 1.59 ratio – Note that gears are generally discussed with mentioning the top gear first like “Twenty. seven, fourty three” Gears are displayed in text as 27:43 with a ” : ” to separate the values. More examples, 44 / 24 = 1.83 ratio and then written and spoken as 24:44, A gear ratio is the relationship between the rotation of the input gear (engine output) and the output gear (wheels). Essentially, it determines how many times the engine needs to turn for the wheels to complete a full rotation. A gear ratio calculator is a tool that can easily determine this ratio, simplifying maintenance decisions and enhancing your …, Simply select a vehicle, and it will prefill the fields in the calculator (Optional) Speed: Choose between mph or km/h. Tyre Size: Enter your tyre size or Outer Diameter (inches). Max rpm: Enter your maximum engine rpm limit. Final Ratio: Enter your final drive ratio. Gear Ratio: Enter the gear ratio for each gear., Also calculates metres of development and (optionally) speed or cadence, and gain ratio. Bicycle 'gear inches' is equivalent to the diameter of the drive wheel on a direct-drive bicycle with pedals fixed to the wheel, or when the number of teeth on the chainring and the sprocket are the same: a 1 to 1 drive. Gear inches is used mostly for ..., In an interest rate swap, the absolute rate is the sum of the fixed rate component and the variable bank rate. In an interest rate swap, the absolute rate is the sum of the fixed r..., Feb 10, 2016 ... Videos every Wed. & Sat. Have a video idea? Suggest it in the comments. Gear Inch Calculator: http://www.sheldonbrown.com/gears/, Kick in high gear with our gear ratio calculator: here, you will learn how gear multiplies speed and torque using only a couple of simple mathematical formulas. Keep reading our article to find out: What is a gear? What is the gear ratio? How to find the gear ratio of a gear train;, Fixed Gear Calculator. Unit. Imperial. Language. Settings. Chain Ring. Rear Sprocket. Tire. Ambidextrous Skid. No. Equivalent Gear ±2% 28×9. 31×10. 34×11. 37×12. 38×12. 40×13. 41×13. 43×14. 44×14. 46×15. 47×15. 49×16. 50×16. 52×17. 53×17. 55×18. 56×18. 57×18. 58×19. 59×19. Calculate. What Is A Fixed Gear Calculator?, Bottom gear / Top gear = Gear Ratio. Example 43/27 = 1.59 ratio – Note that gears are generally discussed with mentioning the top gear first like “Twenty. seven, fourty three” Gears are displayed in text as 27:43 with a ” : ” to separate the values. More examples, 44 / 24 = 1.83 ratio and then written and spoken as 24:44 , Since the planets are rigidly coupled together, the summation of forces on the two gears must equal zero. The force at the sun gear mesh results from the torque input to the sun gear. The force at the second ring gear mesh results from the output torque on the ring gear. The ratio being 41.1:1, output torque is 41.1 times input torque., Since the planets are rigidly coupled together, the summation of forces on the two gears must equal zero. The force at the sun gear mesh results from the torque input to the sun gear. The force at the second ring gear mesh results from the output torque on the ring gear. The ratio being 41.1:1, output torque is 41.1 times input torque., Concrete mixing ratios are the formula for calculating the correct amount of each ingredient used, including water, cement, sand and aggregate, to produce concrete with the propert..., Jan 13, 2015 · Rohloff Hubs. The minimum gear ratio you can use with a Rohloff hub is 2.5:1. Therefore on a 26″ Rohloff bike, you can get as low as 15-95″ and on a 700c bike you’ll get 19-102″. Pinion Gearboxes. Pinion gearboxes have a huge range (636%), providing both lower and higher gears than a Rohloff hub. , Download BikeCalc on the App Store. Combining precise calculations and an intuitive design, BikeCalc provides you everything you need to analyze and optimize the gearing on your bicycle, saving you time, guesswork and potentially a costly mistake. Get the App. Calculate gear ratios given chainring and sprocket (cog) sizes., Understanding the Calculation. The gear ratio is calculated by dividing the number of teeth on the driving gear by the number of teeth on the driven gear. This ratio is crucial in …, This relationship is called the gear teeth – pinion teeth ratio or the gear ratio. This ratio can be expressed as the number of gear teeth divided by the number of pinion teeth. So in this example, since there are 54 teeth on the larger gear and 18 teeth on the pinion. There’s a ratio of 54 to 18 or 3 to 1 this means that pinion is turning ..., About External Resources. You can apply CSS to your Pen from any stylesheet on the web. Just put a URL to it here and we'll apply it, in the order you have them, before the CSS in the Pen itself. , Since the equation for calculating the circumference of a circle is simply pi multiplied by the circle's diameter, you can also calculate gear ratios by comparing two circles' diameters. Two gears, one with a diameter of 6 inches and another with a diameter of 3 inches, will have a gear ratio of 2:1. Most gears that you see in real life have ..., Generally tires squat about 3%. If you are using the calculated diameter, multiply that number by .97 to get a more accurate reading. If you are measuring your tire, measure from flat ground up to the center of the hub and multiply that number by 2. Easy to use gear ratio calculator. Use our gear ratio calculator to find the correct gear ratio ..., Gear Torque (T) = (P * 60) / (2π * N) Where: Gear Torque (T) is the torque required to rotate the gear or the output torque, typically measured in Newton-meters (Nm) or pound-feet (lb-ft). P is the power input to the gear system, usually measured in watts (W) or horsepower (HP). N is the rotational speed of the gear or the speed of the output ..., This mechanism is used for reduction / speed-up gear. In the picture above, meshing is the sun gear A -> the planetary gear B -> the planetary gear C (coupled with the gear B) -> the sun gear D (concentric to but not coupled with the gear B) and the gear A is fixed, while the arm E rotates. To obtain the speed ratio, firstly fix the arm E and ..., To calculate RPM at 60 mph, you need the tire diameter and gear ratio. Use the formula: RPM = (Speed in MPH x Gear Ratio x 336) / Tire Diameter. What is the formula for gear ratio example? The formula for gear ratio is Gear Ratio = (Number of Teeth on Input Gear) / (Number of Teeth on Output Gear).