Helium Racing Q Factor, Crank Length

A Rollout larger than 54 (54.2 and up) produces a ‘Taller’ or harder gear. These ratios travel further than the 54 inch Rollout with each pedal stroke. Higher Rollouts can achieve the same speed of the 54 inch Rollout but at a slower pedal cadence.

Levering the bike side to side rather than pushing it forward is wasted power and not helping balance so bringing everything into the center as much as possible is a big deal. The width of the cranks is termed Q factor and tighter is better. We used to warn against cranks that bow outward but having measured the Q on almost all the brands we realized that most cranks on the market have a wide Q factor regardless of the the shape of the arm. Helium, Rennen, VSR and bombshell rockets are the tighter of the straight arm cranks.

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But my sources tell me that 54 inch rollouts were the industry standard. A Pro size complete bike from that period would likely feature a on Tioga comp III 20×1.75 rear tires. Tires come in multiple sizes, but the most important measurement for gearing is the external diameter of the tire. The external diameter is the total measurement of the outside of the tire.

• Children can start BMX as young as 3 years old if they have the right bike and are conformable at riding.
• Fact is tires are not made consistent and we have found they stretch over time so it will be good to periodically check to make sure your rollouts remain where you want them.
• All kids are different, so it mainly comes down to their height and ability.
• Growing your skill-set and developing bike skill will yield the best results.
• As can be seen from the list above, there are numerous negative, in some cases fatal, outcomes that may result from being overweight.
• If you can’t get an elbow on the competition out of the gate, then it doesn’t matter how much faster your harder gear can go.

These are by no means scientifically tested but the last 40 years of racing proves these rollout to still be effective. The 1 tooth addition to the Cog is equivalent to removing 2 teeth from the Chainring producing a much lighter gearing (much easier to push). Removing a tooth from the Cog increases the overall Rollout equivalent to adding 2 teeth to the Chainring producing a harder gear (requires even more muscle power to push). A total Rollout of 53.9 and lower produces a ‘Lighter’ gear. It’s easier to push from a standing start but doesn’t travel as far with each pedal stroke.

Risks associated with being overweight

Refer to the table below to see the different categories based on BMI that are used by the calculator. Racing BMX bikes are lightweight, designed for speed and stability, while freestyle BMX bikes are sturdier, with thicker frames and tires, designed for maneuverability while doing jumps and tricks. Most BMX bikes have 20″ tires, while the larger frames may use 24″ tires – also known as cruiser class BMX bikes. When figuring out frame size, only the rider’s height is important. This calculator will recommend a BMX frame size based on your height measurement..

With tracks being so much faster, you’d be safe in assuming that racers are running taller gears to push even higher speeds. Some might chalk this up as an accepted industry standard or a method for companies to save money through simplicity. But if we take a look at today’s pro bikes, we see a puzzling outcome.

Rennen “California Gear” Calculator

If you are interested in determining your current rollout, you can plug your info into a gear calculator linked here. These programs, ask for your chainring size, cog size, and rear tire size & model. After entering the information, you’ll be provided with a rollout measurement.

The COVID-19 quarantine has allowed us to work on some new products and create tools we didn’t have time for in the past. With that, I’m zatgo happy to release our new online gear rollout calculator. We recommend that you stay within the ranges provided above for each size bike.

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A sub 54 inch Rollout provides increased acceleration capabilities compared to the 54 and requires less effort from the rider to push each pedal down. If I was choosing between a tighter Q factor or a few grams lighter I would pick the tighter Q factor parts. It’s simply more important than weight and shown to decrease lap times. We sell the lightest and the tightest cranks, bottom brackets and pedals available. BMX Ultra has created a really great rollout calculator that tells you exactly what the distance is covered by 1 full crank rotation based on your tire size and gears. When looking for the correct size kid’s BMX you can either try our kid’s bike size calculator at the top of this page, or you can check out the kid’s BMX frame size chart alow on this page.

Redline/GT and other frames with wider chainstays require a longer spindle to clear longer cranks. Sometimes you can get by with a short BBs on these frames if you are using 120 or shorter cranks. The formula to find the gear inches for your bike is simple. Divide the number of teeth in the front sprocket, or freewheel,
by the number of teeth in the rear sprocket, or freewheel,
and then multiply by the diameter of the rear wheel. This app is great for comparing gearings for racing and sprint training, and also keeping my street/race/dirt bikes feeling the same weather I have big race cogs or little ones.

BMI chart for adults

If two riders pedal at the same exact RPM, the rider with the larger Rollout will be traveling at a higher top speed than the rider with a smaller Rollout. As can be seen from the list above, there are numerous negative, in some cases fatal, outcomes that may result from being overweight. Some rear hubs have two different size flanges and may require two different length spokes, which are listed above. Please note, hubs and rims labeled “Verified” have been confirmed with the manufacture or manufacturer’s website. Non-verified items have been obtained from third party sources, but we are working to verify all items with their manufacturer. Bmxspokecalc.com is not responsible for incorrect spoke calculations.

BMI prime is the ratio of a person’s measured BMI to the upper limit of BMI that is considered “normal,” by institutions such as the WHO and the CDC. Though it may differ in some countries, such as those in Asia, this upper limit, which will be referred to as BMIupper is 25 kg/m2. The developer will be required to provide privacy details when they submit their next app update. Whether it was scientifically accurate or not, no gearing ever felt the way my 50/18 did. Each pedal stroke felt like it accelerated unlike any other combination, and with that, came a mental edge.

Removing a tooth decreases the overall Rollout making the gear lighter (easier to push the pedals). Make sure to tighten this cup if it loosens cup make cause cranks to stop and rider may fall suddenly. The lock ring should be removed and set aside for the moment. Using your hand only to turn the tool at this time until the cup is bottomed on the bearing.

Remember, try and stick to the recommended frame size, sizing up can be tempting but you’re only going to make like hard for your little one. No matter if you are a child or an adult we all come in a wide range of sizes. However, when it comes to larger adults there are fewer options available. Customers are reporting 2 -4 seconds faster from tightening up the Q factor. In fact we find that for a 5 and under rider every 8-10mm tighter results in one second faster on the track. Someone weighting 70 Kg or 154.3 lb bicycling (BMX) burns 297.5 calories in 30 minutes.

• Our goal is to serve as the hotspot for e-bike lovers by providing value through reviews, how-to articles, and detailed guides.
• It’s crucial to win the first portion of the race so we all prioritize first straight performance whenever altering our gearing ratios.
• Installation procedure for Helium Titanium and Aluminum BBs including torque spec for aluminum bolts.
• Now if you measure your own tire circumference and find it doesn’t match what is listed in our calculator then you can select the next closest option.
• Helium, Rennen, VSR and bombshell rockets are the tighter of the straight arm cranks.
• There’s a bit of variation with some being as low as 53 and others pushing high 55s.

BMI is a measurement of a person’s leanness or corpulence based on their height and weight, and is intended to quantify tissue mass. It is widely used as a general indicator of whether a person has a healthy body weight for their height. Specifically, the value obtained from the calculation of BMI is used to categorize whether a person is underweight, normal weight, overweight, or obese depending on what range the value falls between. These ranges of BMI vary based on factors such as region and age, and are sometimes further divided into subcategories such as severely underweight or very severely obese.