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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…

66 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!

    • pepe permalink
      July 11, 2014 13:45

      get a road bike with 650c wheels instead of 700c they are rarer but a much better bet for shorter riders

  6. March 8, 2013 16:33

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

  7. April 29, 2014 05:59

    Great article! I remember it being a pain for me when first looking for a bike. The sizing changes dramatically across brands. I’ve also learnt knowing the type of bike you actually need helps a lot! These guys have a good little guide on choosing the right bike too: which led me to buy a hybrid bike for commuting rather than using an off road bike! Much more comfortable.

  8. May 7, 2014 15:39

    Thought this discussion might be interested in bike ergonomics. I have found two free ebooks on the subject that have been very useful providing two perspective on bike types and riding styles as it relates to bike anatomy and sizing.

  9. July 15, 2014 23:14

    Bike fit freaks! Learn to ride the size you have . Then think about it and realize all the sizes are made to facilitate the manufacturers. I still use 700C wheels mostly but am sliding to 650C for track. Top bars may be changed in virtual length by your handlebar set up. Change your leg movement by trying shorter cranks.

  10. Ryan permalink
    August 14, 2014 14:25

    I used the torso+arm formula and i got 19.75in which would be 50cm. i am 6′ tall with a 34″ inseam. I don’t think that method is very accurate.

  11. LouieC permalink
    August 24, 2014 00:52

    I feel like some of these inseam-to-height ratios/averages are skewed a bit? I don’t have particularly long legs: my inseam (groin to ground) is 29.5-29.75″, and I’m 5’1.5″ tall. None of these charts (except the dutch bike because it is a chart for customized bicycles) include someone of my proportions.

  12. September 24, 2014 16:51

    I was recommended this website through my cousin. I am not positive whether or not this submit is written by means of him as nobody else know such specific approximately my problem.
    You’re incredible! Thank you!

  13. August 23, 2015 13:08

    Some sources claim that road bikes require 1-2 inches clearance while mountain …

  14. August 23, 2015 13:23

    When it comes to cruiser bikes like my own, there seems to be the least …

  15. May 19, 2016 20:37

    Thanks for the charts and layout. Very helpful!

  16. Rob Mason permalink
    September 9, 2016 11:47

    Thanks! This was very helpful: great job of simplification and explanation, good charts.

  17. September 13, 2016 03:33

    Very helpful! thanks

  18. Susan Moss permalink
    October 27, 2016 04:18

    I found the information in the bike sizing article very helpful. I’m shopping for a step through bike and haven’t known what is the right size for me. They have all felt small.

  19. Vitali permalink
    June 24, 2017 02:24

    Strange formula. My torso length is 26 inches and my arm length is about 22 – 23 inches. So I get -4 inches as the result.

    • Billy permalink
      August 31, 2018 03:53

      Either you read the formula wrong, or you need to work on your math. If your torso is 26 and arm is 22, you get 18 inches as a result.

  20. Peter permalink
    August 23, 2017 06:03

    Yes interesting …im 5ft7in the dreaded inbetween size..rode 17in mountain bike for yrs no problem..bought 1st hybrid 18in bang in center for fit acording to hybrid chart and have had to sell after 2weeks due to cronic lower back pain and numbness..tried riser bar position…handlebar exchange..etc…no joy…it can only be the frame size is to small for me…i rode my mates medium giant rapid on a 100 miler only had to put the seat down 2in and it was fine…so us inbetweeners are left confused and bewildered…my experience is if ur like me on the border of the 2 sizes think very carefully before u purchase from mountain to hybrid to road there all different…we live and learn….

  21. Debbie Rush permalink
    November 2, 2017 04:06

    Awesome post. Bicycle tires have two components. The longer number of the tire is in diameter about an inch, and the smaller number is the tire width in an inch. I also maintain a site, hope you like it –

  22. January 23, 2018 15:18

    As a new cyclist myself, I can let you know the most critical component is to get your ass obtainable and just experience. Everything else comes after that, and not anything can probable come before. Great website!

  23. April 17, 2018 05:58

    I am really happy to inform you that your article helps me for find right size bikes.
    And i think it is helps many people.
    Please Publish future this kind of more article.


  24. Sandra Bintly permalink
    June 8, 2018 21:08

    Thank you but it’s going to be difficult for me to measure my husband’s inseam without ruining the surprise for Father’s Day, 🤣🤣🤣🤣🤣

  25. September 26, 2018 00:32

    Thanks for the information! According to the chart, I’m definitely on a bike that is too small. Looks like the bike that I’m using should be for my wife who is almost a foot shorter.

    Do you also have tips for choosing the right size bike for kids?

  26. September 26, 2018 00:47

    Since a lot of the bikes have seats that you can pul up and extend the height for the seat, is there a range that will be still suitable. If the seat can be extended far, can a tall person comfortably ride even the frame is small according to the chart? If it’s ok, how much smaller can it go?

  27. Barbara Carroll permalink
    December 11, 2018 10:34

    I’m 4’11” tall and 71 years old … what size WHEEL should I buy in an adult tricycle? Thanks

  28. December 27, 2018 23:25

    I find some tips on how to choose the right bike here. Get it now

  29. March 26, 2019 19:00

    Excellent! Greatly appreciated.

  30. April 8, 2019 03:10

    You did a great job. Really amazing article you share with us. Thank you man, Now I have a clear idea on Right bike size.

  31. steven lim permalink
    May 11, 2019 06:19

    If the inseam 80cm. What is the seat height ?

  32. June 20, 2019 17:40

    Generally, academics know how to spell in their native language. *too* boring. 1st paragraph, 2nd sentence. Peace.

  33. Ismail permalink
    January 7, 2020 02:43

    If anybody wants to buy a bicycle you can Decathlon for better experience and main thing is that you can try and buy your product

  34. March 7, 2020 14:41


    Thanks for the great article on finding the right size of bike. Its really tricky for the beginner to find correct bike as they need. Happy paddling!

  35. Cungcat permalink
    February 21, 2021 19:41

    This is why I always confused when choosing the right MTB frame size for myself. My inseam seems shorter then the standard human measurements (Height 172.5cm/5’8″, Inseam 72cm/28ich), they never fit in any table. Since I have longer body above my waist, my reach can accomodate 17 inch frame, but my inseam needs a 15 inch frame. Poor me :(

  36. April 16, 2021 07:28

    the best method by far is to go to professional bike shop and use their expertise :D


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