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  1. #1
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    Bike Sizing Questions

    For a 6'4" rider, what specific numbers should one be looking for in a bikes geo to ensure a good fit? e.g, Top tube length, seat tube length etc... and what measurments on ones body should be taken into account (other than height)?

    Or is there no actual answer because different styles of bike and brand cause to many variables?

    In my case Im looking at a Santa Cruz Tallboy LTc, and I sit right on the sizing line between an XL and XXL, and as sizing them up before I place the order is not possible I really need a bit more insight than what is given on the santa cruz website.


    Thanks.

  2. #2
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    There are too many factors that play into good bicycle fit for someone to answer your questions about the 'right' top tube length, etc for you.

    The top shelf approach would be to get someone certified in bike fitting to help you out. Or, look on line for some of the fit guidelines, which will have you do thinks like stand with your back against the wall and shove a book up uncomfortable high up your crotch. These things are worth doing if you have the money and/or time.

    OTOH, if you've been riding a while, you might just measure the effective top tube and seat tube lengths on your current bike and compare those to the Tallboys you're considering. You might also find a way to throw your leg over Santa Cruz bikes with similar dimensions. Does your shop have any SC 29ers? Or, post in the SC forum here and ask if anyone in your area would let you try an XL or XXL SC Tallboy. Heck, see if there's an SC dealer in your area who rents or demos Tallboys.

    I'm 6'1" and ofter fall between L and XL sizes. Early on, I preferred XL for stability, but I've grown to prefer the flicability of L. Don't think I'm going back to XL.

  3. #3
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    Quote Originally Posted by tenbsmith View Post
    There are too many factors that play into good bicycle fit for someone to answer your questions about the 'right' top tube length, etc for you.

    The top shelf approach would be to get someone certified in bike fitting to help you out. Or, look on line for some of the fit guidelines, which will have you do thinks like stand with your back against the wall and shove a book up uncomfortable high up your crotch. These things are worth doing if you have the money and/or time.

    OTOH, if you've been riding a while, you might just measure the effective top tube and seat tube lengths on your current bike and compare those to the Tallboys you're considering. You might also find a way to throw your leg over Santa Cruz bikes with similar dimensions. Does your shop have any SC 29ers? Or, post in the SC forum here and ask if anyone in your area would let you try an XL or XXL SC Tallboy. Heck, see if there's an SC dealer in your area who rents or demos Tallboys.

    I'm 6'1" and ofter fall between L and XL sizes. Early on, I preferred XL for stability, but I've grown to prefer the flicability of L. Don't think I'm going back to XL.
    Thanks for the insight. Some great points to think about.

    Measuring my current ride would be a goer, but with a new bike, I'm going to go up a size (or maybe 2...)

    Sent from my GT-I9000 using Tapatalk 2

  4. #4
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    I've been having a tough time picking a bike too, because I'm a " bigger guy" everyone wants to put me on a bigger bike, but my stand over height is not that high.

  5. #5
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    J, it's probably worth your time to find someone who is an expert in bike fit to help council you or read one of the online fit guides. Have you ever played with stem length and/or seat position?

  6. #6
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    One other quick thought for J, I've heard it from reliable, expert sources that effective top tube length is more important than stand-over height. So, if you, have a relatively long torso with and shorter legs, your best fit might be on a bike a higher than comfortable standover--though it seems you should be able to find a bike that fits well with comfortable standover given all the bent top tubes these days.

    Be careful of bike shops trying to sell an old bike that doesn't fit you well just to get it off the floor.

  7. #7
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    I'm 6'4" and would be going with a XXL SC TB LT and a 50mm stem on it.

    For me to be comfortable, I need at least 25.5" ETT and 20 ST.

  8. #8
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    I'm a believer in reach and stack measurements. Those are the horizontal and vertical distances between the bottom bracket and top of the top tube. The measurement that everyone looks at first: effective top tube, is dependent on the seat tube angle, and may not be a good predictor of the bike's fit. For example, one of my bikes has a longer ETT by 1/2" but if feels shorter than the other, and sure enough, the reach is shorter. Unfortunately, a lot of bike companies still aren't publishing reach/stack numbers on their geo charts.

    At 6'3" and with 33" inseam, I fit between L and XL depending on the company. Some of that is driven by how I want a bike to fit me: do I want a maximum effienciency XC racer type fit, or a more compact, upright all-mountain type fit, for example. It's hard to answer those questions without some experience. I have had a bike too big for me and it really sucked. I've also had one that was borderline too small, and that wasn't great, but it wasn't bad enough to shake me from my allergy to oversized frames. I also prefer the compact and upright fit, so I'll take the smallest frame I'm comfortable on.

    I've ridden enough bikes to know what fits me and what I want, but it didn't happen overnight. There really is no substitute for a test ride, but options can be limited. I know how frustrating it can be to try and visualize what the geometry charts actually mean to you. Good luck.

    Here's an illustration of these measurements:
    Name:  ImageUploadedByTapatalk1352606968.237647.jpg
Views: 258
Size:  35.9 KB
    "Back off, man. I'm a scientist." - Dr. Peter Venkman

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  9. #9
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    Quote Originally Posted by eurospek View Post
    I'm 6'4" and would be going with a XXL SC TB LT and a 50mm stem on it.

    For me to be comfortable, I need at least 25.5" ETT and 20 ST.
    Thanks!
    The large has a 25.1" TT and XXL 25.9" How noticeable would the extra .8" be?
    Im a bit scared that 25.9" TT might be too long. I still want that upright All-Mountain fit. I dont want to be leaning heaps forward to get to the bars.

    And how do these measurements corresponds with body measurements? Arm length??

    And whats the general consensus, longer TT and short stem, or shorter TT and long stem. Im leaning towards the short stem option.

    Quote Originally Posted by evasive View Post
    I'm a believer in reach and stack measurements. Those are the horizontal and vertical distances between the bottom bracket and top of the top tube. The measurement that everyone looks at first: effective top tube, is dependent on the seat tube angle, and may not be a good predictor of the bike's fit. For example, one of my bikes has a longer ETT by 1/2" but if feels shorter than the other, and sure enough, the reach is shorter. Unfortunately, a lot of bike companies still aren't publishing reach/stack numbers on their geo charts.

    At 6'3" and with 33" inseam, I fit between L and XL depending on the company. Some of that is driven by how I want a bike to fit me: do I want a maximum effienciency XC racer type fit, or a more compact, upright all-mountain type fit, for example. It's hard to answer those questions without some experience. I have had a bike too big for me and it really sucked. I've also had one that was borderline too small, and that wasn't great, but it wasn't bad enough to shake me from my allergy to oversized frames. I also prefer the compact and upright fit, so I'll take the smallest frame I'm comfortable on.

    I've ridden enough bikes to know what fits me and what I want, but it didn't happen overnight. There really is no substitute for a test ride, but options can be limited. I know how frustrating it can be to try and visualize what the geometry charts actually mean to you. Good luck.

    Here's an illustration of these measurements:
    Name:  ImageUploadedByTapatalk1352606968.237647.jpg
Views: 258
Size:  35.9 KB
    Thats some awesome info, much appreciated. The pic is a big help too.

    So, how does the stack height correspond to inseam measurments?


    Sorry for all the questions, I just dont want to make another expensive mistake by buying a bike the wrong size...

  10. #10
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    No, that's standover height. Stack is the measure of how tall the frame is.

    To give credit, that illustration came from this site: http://bikegeo.muha.cc/
    "Back off, man. I'm a scientist." - Dr. Peter Venkman

    Riding in Helena? Everything you need to know, right here.

  11. #11
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    Quote Originally Posted by stalks View Post
    Sorry for all the questions, I just dont want to make another expensive mistake by buying a bike the wrong size...
    Understandable. That's what the forum is for.

    Here's an idea- if you have somewhere to test ride ANY bike to see how it fits, you could compare those geometry numbers to the frames you're looking at.
    "Back off, man. I'm a scientist." - Dr. Peter Venkman

    Riding in Helena? Everything you need to know, right here.

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