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Bike 101: How To Find the Right Size Bike

July 6, 2010



A very basic thing required when shopping for bikes is the understanding of size and measurements. Ironically, this is one of the last things I figured out, because it just seemed to boring… all those charts and numbers. A bike either seemed to fit me or it didn’t. While this worked out just fine when I was getting fitted by others at bike shops or bike rental places, this system failed me when trying to shop for bikes online. Perusing Craigslist for my dream bike required a bit more bike knowledge than I had, including an understanding of proper sizing.

Being the academic that I am, I thought compiling a ‘research post’ of sorts might help someone else trying to find the right size bike. Unfortunately, I found that most google results for said term only pulled up sizing charts for mountain bikes (we seem to be a very mountain bike dominated society here in the US). It took a bit more digging to compile sizing information on ‘comfort’ bikes or non-sporty bikes. And, as a gender scholar, I really couldn’t help but notice that all size chart caricatures were male…hmm…but that’s another post entirely.

For now, here is my compilation of information on how to find the right size bike for you, be it a Dutch bike, a cruiser, a mountain bike, or a road bike…

1) Find Your Measurements

To figure out the right size for you, a few basic measurements are necessary:

- Your leg inseam (from your crotch, where the saddle would be, to your foot)

- Your torso length (from your crotch to your sternum – the V-shaped curve below your neck)

- Your arm length (from the end of your collarbone to the middle of your closed fist)

2) Know Some Basic Formulas

Your inseam is the most often consulted one. Most bike size charts note the stand-over height. This is your inseam plus another 1-2 inches for comfortable clearance of that top tube. Some sources claim that road bikes require 1-2 inches clearance while mountain or commuter bikes need 2-4 inches. (If you’re using a bike with a step-through frame, then that measurement of reference doesn’t really work since the top tube is lowered.)

Another formula is that of the top tube length. I used to scoff at these details but I’ve come to appreciate that finding a road bike that is on the compacter side with a shorter top tube makes a big difference for me. I have a short torso so that distance between the saddle and the handlebars can really affect my ride. To figure out your ideal top tube length, do the following math:

(torso length + arm length) / 2 = x

x – 6 = top tube length

(Add your torso length to your arm length, divide that by two, and subtract six). This will tell you in inches what the ideal distance would be between your seat and handlebars.

3) Consult a Few Size Charts

Image Source

Image Source

Image Source

Dutch Bike Sizing:

Image Source

Cruiser Sizing:

When it comes to cruiser bikes like my own, there seems to be the least amount of available information in terms of sizing. Cruisers are commonly sized in terms of small, medium, large, etc. rather than in inches, so there seems to be less of a direct numerical correspondence between the rider’s size and the bike size. I’ve found this video most helpful in demonstrating how a well sized cruiser should fit relative to body size. This confirmed that my Electra cruiser is a good fit for me, since it mirrored the fit demonstrated on the second and more suitable bike shown here…

Finding the right size beach cruiser bike for a women from Beachbikes on Vimeo.

4) Trial and Error

Ultimately, finding a well fitting bike is like finding any well fitting garment – only trying it on will really tell you how it fits. As Alan of EcoVelo so eloquently put it, ‘Bike sizing is an art not a science‘. Figuring out some basic math and having a few numbers for reference will certainly help get you in the right direction and it will even allow you to rule out easily identifiable ‘too big’ or ‘too small’ bikes when shopping online, but nothing will truly confirm that a bike is the right one for you until you take it for a spin. And bike fit can also be adjusted by moving the height of your seat or your handlebars. It’s all about experimenting with what feels right and comfortable to you, which is also something that might change over time as you get more confident on a bike and maybe even alter your riding style. The above are just some basic outlines for the next time you’re procrastinating by looking up bikes on Craigslist and wondering whether they’d be a right fit for you…

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12 Comments leave one →
  1. Tizzle-T permalink
    July 6, 2010 19:50

    Good info, thanks!!

  2. July 6, 2010 21:28

    Yes, thanks! Very helpful!

  3. July 7, 2010 02:13

    I also knew nothing about bike sizing when I first decided to buy a road bike on Craigslist. Fortunately, my more bike knowledgeable friends helped me out. I stood over my friend’s bike, lifted it up, and a friend told me that I needed a 54cm. I trusted the advice, and that’s the size bike that I bought. It’s definitely the right height for me, since my legs stretch out nicely extending when I’m pedaling. I had been borrowing my dad’s bike that was probably a 58 cm. With the seat at the lowest position, pedaling was fine, but it was hard to get on and off of it. I definitely had a couple of comical falls just trying to get off that bike!

    I didn’t know that bikes came in different top tube lengths. The second time I road my new bike, it felt like the top tube was too long for me, but I’ve gotten used to the length and position in subsequent rides. Buying future bikes, I”ll pay more attention to that. Thanks for the tip!

  4. August 19, 2010 21:14

    I wish I had this info 2 years ago when I bought my bike – I decided to just order what my friend was ordering online and hated learning to ride on it, but never knew why, so I stopped trying.

    This year I took that same bike out again and really just totally injured my ladybits with the bike setup, learning how to ride again, in one day. Finally I forwarded a picture of me on that bike to my friend and her gf, who works for a bike company, and they suggested the mountain bike was too big and I was having to lean way too forward.

    Now I have a smaller-wheel sized Huffy and while I still can’t steer like a normal person, I have a willingness to get on the bike and try like I’ve *never* had before. Her name is Kate Jackson (burgundy Huffy Bay Pointe cruiser) and I love her.

    • August 19, 2010 21:49

      Jesse.anne.o – it’s amazing what just having the right size bike will do! My experience with a road bike sounds really similar to yours – there was a lot of lady bits injuring going on because the bike was too big and the top tube was higher than my inseam so anytime I came off it without slightly tipping it to the side, there would be a very unfortunate collision. Just getting a smaller road bike made a huge difference in my wanting to ride that style bike.

      Let’s see pics of you and Kate Jackson! :) Are there any on your blog or on Flickr?

  5. Laura permalink
    June 14, 2011 08:50

    Wow! Thanks so much for posting this! I just found this info via your year blog anniversary post and I was very happy to see that someone else had taken the time to research an issue that drove me nuts also a year ago. Last June I decided to donate a very cheap and crumbling mountain bike that was not doing it for me, and started to shop for a vintage commuter bike since I was on a budget. Because I started my search at a local bike organization that repairs and sells donated bikes, sizing was the first thing I stumbled upon and made me a bit frustrated since nobody could really tell me how to measure a bike unless it was a road male bike. Then, like you, I ventured Craigslist to no avail and in the end, I bought my vintage 3 speed bike from a local bicycle shop where they helped me to guess my bike size. My Internet search was not as successful as yours, but taught me something about road bikes. It looks like women who are my height, 5’4″, will have to either look for road bikes with a lowered bar or get a customized frame since it’s hard to find small frames in the market. If it wasn’t for the hope in this bit of information I would had given up on road bikes altogether!

  6. March 8, 2013 16:33

    Helpful, thanks! I’ve lived in SF for over two years, about time I get myself a bike!

Trackbacks

  1. The Huffy Project « Simply Bike
  2. happy one year to simply bike! « Simply Bike
  3. half way there to our own bike share program « Simply Bike
  4. Finding the Right Bike for You! | The Daily Quirk
  5. Resources: Finding the Right Bike

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