How to Find the Right Size Ebike

Tips for ensuring you get the proper fit.

Two Male Adults demonstrating Bike Sizing
Comfort is the ultimate goal in sizing yourself for a new bicycle or ebike.Jeff Allen

Identifying your bike size is a key element in the shopping process. Here’s how to quickly find the right size bike.

We’ll start by defining some words you’ll hear during the fit process.

  • Toptube: As implied, this is the uppermost tube connecting the seat tube and headtube. It dictates the length of the frame, and usually parallels the ground or slopes downward toward the back of the bike.
  • Seat tube: This is the tube the seatpost slides into. It determines the height of the frame.
  • Headtube: This is the foremost tube on the bike. The fork passes through the headtube. We define it here as it is an important reference point for reach (defined below).
  • Bottom bracket: This houses the crankset spindle, and is usually the frame's lowest point. This is another reference point for terms defined below.

Back when bicycles all used variations of the diamond frame shape, toptube and seat tube length were sufficient for frame sizing. But modern frames can vary greatly, and we now use two measurements called reach and stack. The other important term you’ll need to know is standover height.

  • Reach: This is the distance from the top-center of the headtube to the centerline of the bottom bracket measured parallel to the ground.
  • Stack: This is the vertical distance measured from the centerline of the bottom bracket to where it intersects with the reach line.
  • Standover height: Often shortened to "standover," it's measured from the ground to the center of the toptube.

Pick a frame size, ideally in a shop with a full size range offering of the model or models that have piqued your interest. You can whittle it down fairly quickly by simply standing next to the bike. When you find one that looks like the correct size, straddle the bike. If you have to stand on your toes, the bike is too big. This is why standover matters.

With feet flat on the ground, check the distance between the toptube and your crotch. There should be 2 to 5 inches on bikes with a heavily sloping toptube.

Once you’ve found a suitable candidate, move on to setting your saddle height. (Pro tip: In cycling, the seat is called the saddle.) The easiest way to do this is to turn the crank until its arms are parallel with the seat tube. Make sure the top of the saddle is level. Now sit on the saddle and place one heel on the pedal. This should net you a straight leg. If you can’t reach the pedal, the saddle is too high; if your leg is bent, it needs to be raised.

Now is a good time to check the fore/aft position on the saddle. Ideally you’ll have a vertical line that passes through the pedal spindle, the ball of your foot, and the face of your kneecap when the pedal is in the forward, 3 o’clock position. If that’s not the case, move the saddle back or forward until you find that line. If you can’t achieve this, you may need a different length of cranks or a seatpost with a different setback.

Check your reach next. You should be able to reach every point on the handlebar without locking your elbows or experiencing back pain. It’s important to check reach with the handlebar turned, as well as straight ahead. If you can’t reach the handlebar at all of these points, raise or lower the stem. If you still can’t reach the controls comfortably you will need to look at a longer or shorter stem, or possibly a different-length frame. Road and mountain bikes will usually have a more aggressive (less upright) position than cruisers and hybrids.

If you are looking at other models or brands, you can use the reach and stack measurement from this bike to find your size in another bike without repeating the process.

Remember that comfort is the ultimate goal, and the procedure above is just a starting point. If, for example, you find that the proper saddle height for pedaling will have you standing on your toes when stopped, go ahead and lower the saddle until you can stand flat-footed. But if you start to feel knee pain, raise it back up. Also, if you are adding an ebike to your existing stable of bikes, match the measurements of your current bike or bikes.

If this is your first bike in more than a decade, remember that you will feel some pain due to different muscles being engaged. To ease into the sport, and if you feel the need to make adjustments, keep them small (5 millimeters or less) and change only one thing at a time. This will make it easier to keep track of what works and what doesn’t.