Bicycle sizing

  • MSUBioNerd

    Posts: 1813

    May 04, 2008 8:00 PM GMT
    I admit up front: I'm clueless.

    I don't currently know how to ride a bike. I want to learn how. Because it's graduation season and I live near a huge school, it's a good time to find used bikes for cheap. In the past half hour of trying to figure out what size of bike I need online, I've come across a number of different formulas. So, I turn it over to you guys, who know what you're talking about and aren't trying to sell me something. I'm 6 foot tall, and my inseam is 33 inches. Most likely, I'll be either picking up a mountain bike or a road bike (depending on what's available and what cost), but in either case I plan on using it on city streets and/or sidewalks, not offroad. There are some mild hills around here, but given that I'm in Michigan it's not like there anything particularly steep. Any suggestions on bike size would be welcome.
  • NYCguy74

    Posts: 311

    May 05, 2008 12:26 AM GMT
    What i've heard is standing over the bike with both feet on the floor, you should have a couple inches clearance between the top tube (bar that runs horizontally from handlebars to the seat) and your crotch. I'm similar size to you and just got a new bike at my local bike store and they set me up with the jumbo size of this bike. Canondale Comfort for some relative measurements.

    You might want to check with your local shop. they might have some resale, or they can at least go over basic sizing with you. and help you familiarize yourself with various equipment.
    Also you should buy a new helmet from them. You can get one for $40-60 and it's worth the peace of mind to know you're not getting used or possibly damaged equipment.

    Plus if you've never ridden they might be able to give you lessons or at least some pointers.
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    May 05, 2008 12:32 AM GMT
    Depends on the kind of riding you plan on doing as well - more cross country/city riding 21 inch is fine. More agressive (ie downhill wooded fun stuff) go with 18 because they are smaller lighter and give you more control.

    The best way to determine what is best for you is to go to a bike shop and talk to the guys there...
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    May 05, 2008 2:06 AM GMT
    A word of warning on the "standing over the bike" rule of thumb to size your frame. This is used all over and you can be screwed by relying on this if your leg length to height ratio isn't "normal."

    A big chunk of my height is above my waist -- I have short legs for my size. So I always get put on a smaller frame by so-called experts who only look at how my legs relate to the pedals. Nobody looks at how my upper body relates to the handlebars. So pay attention to both!

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    May 05, 2008 4:28 AM GMT
    I've never purchased a used bike but I have bought many new ones. And before I guy anything, I go to a bicycle shop and get measured. It is more important than you could imagine.

    Even if you are not buying from a shop, go in and look at bikes. Have them measure you up and find out the size for you, and it won't cost you a thing.

    After you find yourself a bike, do spend the money to go in and get everything set up exactlly how it is suppose to be for your body. There is no standard. And even if it costs you a little bit of money, it is well worth the injury prevention.
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    May 05, 2008 1:30 PM GMT
    OK, I am exactly your size. I am 6 foot tall with a 33-inch inseam. My bike is a 20-inch but I think you could go for a 20 or 21 inch. After you buy your bike make sure you get it sized for you, which is where the seat should be placed. This is important so that you get the most power out of each stride. Your leg needs to come down at the bottom of the rotation so your knee is just very slightly bent. Also, this is good for your abs to get a workout. There may be a variation in the length of our legs depending on where you like to where your pants so the inseam may not be a perfect match. Good luck and have fun.
  • cowboyathlete

    Posts: 1346

    May 05, 2008 8:19 PM GMT
    polobutt saidI've never purchased a used bike but I have bought many new ones. And before I guy anything, I go to a bicycle shop and get measured. It is more important than you could imagine.

    Even if you are not buying from a shop, go in and look at bikes. Have them measure you up and find out the size for you, and it won't cost you a thing.

    After you find yourself a bike, do spend the money to go in and get everything set up exactlly how it is suppose to be for your body. There is no standard. And even if it costs you a little bit of money, it is well worth the injury prevention.

    Amen to that. A bike purchase is something like buying clothes - they have to fit.