What Size Electric Bike Do I need?

Shopping for an electric bike doesn’t need to be a massive headache.  It is a lot like shopping for a regular bike; the main difference is that these bikes have a motor added as a bonus to be used in combination with your pedals.

The Steps to Choosing the Correctly Sized E-Bike for You

  1. Select the correct frame size
  2. Select the proper seat for your sit bones
  3. Calculate your seat height
  4. Calculate the seat position
  5. Adjust the handlebars
  6. Select the right type and engine. 

Picking the correct size electric bike requires sifting through countless internet forums and blogs trying to find all of the information needed to make a decision. With conflicting information out there and every salesperson in it for themselves, it can be worse than shopping for a car.  Thankfully we have compiled all of the things that you need to consider when selecting the correct size electric bike. 

Electric Bike Size Chart

The size chart method is a great reference tool for choosing the correct bike size. The best way to find a proper measurement is to measure your inseam. After measuring your inseam, then you want to see the appropriate size bike. 

InseamFrame Size
24-29”14”
25-30”15”
26-31”16”
27-32”17”
28-33”18”
29-34”19”

Another size chart method is by measuring your height and then finding the corresponding frame size on the chart below. 

HeightFrame Size
4’10”-5’1”14”
5’1”-5’5”15”
5”5”-5’9”16”
5’9”-6’0”17”
6’0”-6’3”18”
6’1”-6’6”19”

Inside Leg Measurement

Measuring your inseam, or inside of your leg is the most effective measurement system for picking the current bike size. To measure your inseam, you start at the crotch and measure down to the end of the leg.  Take this measurement is Centimeters (CM) for accuracy. 

There are various formulas that you can use to pick the right size electric bike depending on what type of e-Bike it is. You’ll need to know your inseam length to calculate correctly.

The Formulas are :

City Bike

X =(Leg_Inseam_In_CM)(.685) 

Mountain Bike

X =(Leg_Inseam_in_CM)(.66)

Road Bike

X = (Leg_Inseam_In_CM)(.70)

After you input your inseam into the formula, You then get the frame size in CM that you need. Don’t forget to round up or down as the CM will not be exact.

After finding the correct size frame for your bike, the next step is selecting an excellent sized seat. Picking the incorrect seat or seat height can lead to an uncomfortable riding position and less enjoyment.

Pro Tip! Bump it up a Size.

If you are close to the next size, then get the next size up. You want to be comfortable. For example, if you are right on the cusp at 39.37 CM, this would give you a frame size of 15.5; go with the 16-inch frame size.  

Seat Height

The saddle is the next most crucial selection in picking the correct size bike. You need to measure the distance between your sit bones. You can place a flat piece of foil on a couch cushion. Sit directly on the foil, and lean slightly to the front in a riding position. Lift your feet off of the ground. 

You will see two indents, and then you measure the distance between the two deepest points to get your sit bone measurement. This measurement will help you pick the correct size seat for your bike. 

Based on your bike size selection, and the seat size, you then need to select the seat type, several websites have online tools to help you with choosing the correct model for your riding style. 

The height of the seat is more important than the type of the saddle; you want to sit high enough to have a slight arch in your back when leaning forward. There are several different methods to find the correct height.

The Holmes Method

The Holmes method states that the perfect riding position is where the angle of your knee is 25 degrees at its lowest position. To use this method, you need to record yourself for about one minute on your bike in a stationary position. 

Measure the angle your knee is at right at the lowest part of your petal. Raising and lowering the seat height has an inverse effect on the angle of your knee. To reduce the angle that your knee is at, you raise the seat, To increase the angle you lower the saddle. 

The next step is to check the setback on the seat. Take a balanced object and tie it to a string after placing your pedal in the horizontal position. Dangle the line down to the bottom, putting the top of the line on your knee. The line should run right through the center of the pedals axle. 

Make your adjustments as needed. If it falls short of the pedals axle, then move the seat forward, if it is ahead of the pedals axle then move the saddle back until the line matches the pedals axle. The bike saddle always needs to remain in the horizontal position unless you have a medical condition that requires you to slant the bike saddle forward. 

Alternative Methods for Measuring Seat height

Two other unconventional methods will work for most commuters, especially if you don’t have access to a practice roller. 

The 109% Method

Take your inseam measurements and multiply them by 1.09% or .0109 for accuracy. This method measures your height in MM from the ground.  You are going to need to convert your Inseam into millimeters by multiplying by ten. 

  1. (Inseam_in_CM) X 10= MM
  2. (Inseam_In_MM) x .109 = Seat Height in MM
  3. Convert MM to Inches from the ground. 

Heel to Ground Method

Get on the bike and ride the bike around a little bit to get settled in a comfortable riding position. Get going for decent speed and then pedal backward. The heel method states that your heel should slightly lift off of the pedal for the ideal sitting position. 

The LeMond Method

Take your inseam measurement and multiply it by .883 and then subtract for any variables. If you have thin soles on your shoes, take off 2 mm, and 3 mm for clipless pedals. Measure your height from the crank arm to the top of the seat. 

Handlebar size

Cycle Basket recommends that you position the handlebars about 1-2 inches below the height line of the seat. And 1-2 inches from the tip of your fingers and forearm from the tip of the saddle.  

Types of Bikes

Electric bikes have been in use around the world for over a decade. There are no limitations to the types of electric bikes that you can find.  

Some of the more popular options are:

  • City Bikes
  • Mountain Bikes
  • Road Bikes
  • Recreational Bikes
  • Motor Cross Bikes
  • Scooters
  • Mopeds
  • Transport scooters
  • Fat Tire Electric Bikes

Classes of Bikes

Apart from having different types of electric bikes, there are also different classes of electric bikes. Picking the correct level is part of choosing the proper size bike. The battery size, throttle, and speed of the class of electric bike you want to affect how the bike performs.  

A Class one bike is the most commonly accepted electric bike and is perfect for beginners. This bike will only help you accelerate to 20mph and then let you pedal from there. For beginners, a class one vehicle is usually the place to start. 

The Class 2 bike has the pedal assist up to 20 MPH. A class two electric bike also has a throttle only mode that will help you cruise safely along to your destination.  

The Class three bike is one o the more popular styles of an electric bicycle; these bikes get all of the attention from fans. Class 3 electric bicycles are fast performing bikes reaching speeds upwards of 28mph.   The stronger engines allow you to keep up with traffic and climb hills better.  

The Class 4 electric bike is considered a motorcycle. The Class 4 bike requires insurance and a motorcycle license to operate. Class 4 is any motor size over 750W.

Engine Sizes

Electric bikes also have different engine sizes. The top sizes range from 50w-750w for class 1-3 and over 750w for anything class 4 and above. The bigger the engine size, the more power the engine will have to get you over the top of hills. 

If you weigh over 200lbs, you need at least a 350 W motor for your electric bike. This size motor will help you get over hills as well but will perform flawlessly in response to the weight of the rider. 

A 500W motor is a powerful motor, but remember that electric bikes can only go as fast as the gears will let them go. You need to match the power that you need for your commute. The 750W motor is going to be extremely powerful. 

The size of the engine in electric bikes doesn’t matter all that much. The gears and gear ratio is what allows the bike to go the speeds that it does. The engine turns the apparatus with the help of your pedaling, and then the gears will eventually reach their maximum speed.

Weight Limitations

Each E-bike will have its weight restrictions, which are determined by the engine size and the suspension system. Most bikes can easily handle 200-350 lbs. Each bike is going to be rated differently based on several different factors, including:

  • Frame size
  • Tire size
  • Suspension
  • Engine size and weight
  • Brake system
  • Saddle height
  • Cargo space
  • Added accessories

Each manufacturer will have weight restrictions listed on the bike for sale. If you are building your electric bike, then go with a direct drive motor rated for higher than 200lbs.  

The Warranty 

Warranties can be useful and making sure that you have one for replacement parts, and labor is almost a necessity when looking for a bike. Most manufacturers will offer a 2-year limited warranty with parts and labor. 

Under regular use, you should expect no problems with most bikes during the warranty period.  The motor should have a minimum of one year on the engine and controller. Depending on the battery type that the electric bike comes equipped with would depend on the warranty that you receive. 

An Ideal Lithium-Ion battery should give you a warranty for 2-3 years. If you have issues with your lithium-ion battery before one year, then it should be covered. Most lithium Ion batteries should last 3-5 years. 

Some warranties are more like free part plans; they allow you to switch out defective parts for new ones. Sometimes this can be an excellent choice if you are pretty handy with a wrench. Getting a warranty that values your business as a customer would look ideal to you. A guarantee that is only good for one year, on a bike that claims 3000 cycle hours, doesn’t add up. Please pay attention to how much the manufacturer is guaranteeing their product.  

Motor placement

There are two primary placements for the electric motor on a bike. The Hub Motor and the mid-drive engines. There is also the less popular friction motor that tends to be the cheapest option for an electric bike. 

Mid-drive motors are mounted where the crankshaft would go. The engine is linked to the chain and provides either a single gear or multiple gear options. Mid Drive motors give better power and more performance than the Hub Drive motors. 

The hub spot motors are mounted to the rear wheel, or the front wheel and drive the bike forward. The most common spot to mount the hub spot motor is the rear wheel.  Since it adds weight to the bike, installing the hub motor to the rear wheel is the most preferred method. 

The friction motor is the easiest to use; it sits below the seat and turns the rear tire of the bike. The friction motor doesn’t work well in wet conditions, and it can wear the tread down on your bike tires. The friction motor is excellent for getting a feel for riding an electric bike, and they don’t go too fast either. 

Gears on your Electric Bike

Gears on an electric bike are not typically a conversation that comes up when talking about electric bikes, mainly because after adding a motor to the bike, anything over 200lbs is direct drive and not gear driven. 

If you are choosing gears for your bike, you are most likely looking at mountain bike gears, which will help with long term riding up and downhills. For cruisers and commuter bikes, the need for speeds is minimum unless you live in a mountainous area. 

The gears tend to be inside the wheel hub protected from the elements. Another option is the electronic shift mechanism, which allows shifting during high-pressure moments. You can use some different shifting styles on your electric bike if you choose to have gears in your powertrain. 

Most road bikes will have their shifters next to the brake levers, similar to thumb shifters; you hit the shifter button to shift the gears. One single shifter on each handlebar controls the different speeds on either the front crankset or the rear cog set. 

Battery Types

There are different types of batteries for your electric bike that you can use. The most common is the lithium-Ion cobalt battery packs. You can get different lithium-ion battery packs, but the cobalt magnesium is the most common for electric bikes. 

The sealed lead-acid batteries allow slightly for overcharging, but when these go out, they are out, there is no reviving them. The sealed lead-acid batteries are suitable for shorter distances as they need charging more often than lithium-ion batteries. 

Lithium-Ion batteries work by linking individual cells together to hold a charge; they are susceptible to overcharging. A safety cutoff is needed to avoid overcharging a lithium-ion battery for your electric bike. Overcharging the cells inside a lithium-ion battery will damage the cells and potentially cause a fire. 

The SLA or Sealed lead-acid batteries are heavy, but they are also really cheap. These batteries are best for high powered short-distance rides. 

Here is a Youtube Video that explains the different types of electric bike batteries and their uses. 

Battery Comparison

There are different advantages and disadvantages to the different battery types for your bike. You want to consider several aspects before purchasing your electric bike. Besides the size of the battery, you also want to consider the budget between the two types of cells. 


S.L.A.Lithium-Ion MagLithium-Ion Phos
PowerHigh short burstSteady long low currentConstant low current
LeakproofYesYesYes
Good for High PowerYesNoNo
HeavyYesNOYes
Cycles1-2001500-22001500-2200
Long-Lasting Rank 321

The S.L.A batteries will be the cheapest, heaviest, and won’t last for long periods. They do, however, provide a short burst of high current to the motor. They are great for high-performance electric bikes. 

The Lithium-Ion magnesium and phosphorate batteries work in similar fashions just with different main ingredients. They both tend to be more expensive than the lead batteries, but do have a longer life cycle. 

Mounting the battery to the frame is another concern that most electric bike owners struggle to solve. If there is no mounting bracket already installed onto the structure of the bike, then you may need to use an alternative method. 

Range

Several factors need to be taken into consideration to give you the exact range an e-bike will go on a single charge.  Looking at the batteries capacity or amp hours is the first start; this is the maximum amount of time that the bike will run on a full charge. 

The electric bike is the same as an electric car as far as the range is concerned. It depends on the different factors that you face out of the road. 

  • Start/stop
  • Hills
  • Speed
  • Wind Resistance
  • Temperature
  • Turbulence
  • Terrain
  • Battery age

Electric bikes are all going to have their rating system for how far they can go on a single charge. You want to calculate the watt-hours of your bike and realize that each mile driven will use about 20-watt hours. 

To Figure Time: (Amp-hours) X (Volts)

To figure distance: (Amp-hours) X (Volts)/20

Accessories

There are a ton of accessories for electric bikes, all having their purposes. One of the most recommended accessories is mirrors. The Mirrcycle mirror (see on Amazon) provides a handlebar-mounted mirror that allows you to see behind you. 

Mounting safety lights to your electric bike can be the difference between being seen at a crossing intersection and not being seen.  Running the headlamp in the daytime is not for you to see where you are going; it is for other people to see you coming. 

A helmet should be worn anytime you get on a bike, and especially so for riding an e-bike.. Newton’s third law of physics can either be your friend or leave you with a half a million-dollar hospital bill. Wear the helmet. 

Remember that your stopping distance is going to be longer the faster you go. Having a good set of brakes for your electric bike is necessary for safe travels. If you are doing a conversion, then you need to convert the braking system to adjust for the increase in speed. Hydraulic disc brakes work well. 

Maintenance 

Five components need to have maintenance performed regularly on them. The battery, powertrain, tires, brakes, and engine.  Maintaining your electric bike is the only way to prolong the life and experience of traveling on an electric bike. 

Lithium-Ion Batteries need to charge, and gimmicks like surge charging don’t work. Each cell inside the battery has about 1000 charge cycles in them. Charging your battery after every use is the only way to extend your battery life and maintain its life cycle. 

Most engine components will require very little maintenance on an electric bicycle. Depending on the type of engine you selected will depend on the maintenance that you need to complete to maintain the dependability of the engine. 

Performing regular maintenance on your braking system requires a little time and effort to keep them running well. Tightening the cables, filling the fluids regularly, and changing the brake pads or discs when necessary are all part of the maintenance procedure for electric bikes. 

Other Parts that Need Maintenance 

The power train is the easiest to maintain; it requires chain replacement if there are broken links and some chain oil. Putting some oil lubricant on the chain will clean the chain from dirt and grime as well as extend the life of the chain of your bike. 

The tires and Inflatable tubes need to maintained regularly. Most bike tires will last for around 2,000 miles, with no need to replace them. Patch up any holes inside the inner wall with a tire patch. The tire needs to maintain its proper inflation levels to prolong the life of the tire. Carry a small tire pump to fill the tire with air in between sessions. 

Pro-Tip

Line the inside of your tire with a layer of Duct Tape; this will help save your tire tube when riding in rough terrain. Pre-fill your inner tubes with a tire sealer and carry extra inner tubes and tire fillers with you.

Final Thoughts/ Conclusion 

Selecting the perfect fit bikes comes down to a few primary concepts. Choosing the right frame size, bike style, and engine size are just the beginning of a more magnificent adventure.  Getting over the anxiety of making the wrong decision is only a part of selecting the correct size bike. Trial and error are going to be your friend in this case. No one answer fits all situations and scenarios. Buy the size for today and plan for tomorrow.

Share this Post