When is a BB too high?

Discussion in 'Recumbent bicycles' started by Stratrider, May 18, 2003.

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  1. Stratrider

    Stratrider Guest

    I joined the recumbent world in 1999 largely because I found that recumbent design accomodated the
    human form! The bike fit the body rather than forcing the rider to contort to the bike! I still ride
    a faired Stratus and find myself still loyal to the LWB, low BB design. While I have been (and still
    am)close to adding a SWB to my lonely Stratus, I find myself drawn to SWB bikes with only moderately
    high BB. Yet as I follow the evolution of recumbent design, I notice the BB continues to get higher
    (ie high racers like the Strada). I guess my hope looking forward is that new recumbent designers
    and manufacturers not completely forget ergonomics while in search of performance. We already have
    sub 20 pound performance machines. It's just that they hurt too much!

    Jim Reilly Reading, PA
     
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  2. PaPa

    PaPa New Member

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    "When is a BB too high?"

    When it becomes uncomfortable, painful or annoying.

    Find a find comfortable position, then seek a bike with BB height which accommodates this. For me, the Rans V2 BB is too high, while the Stratus and Tour Easy is too low. For LWB's, I fit 19" seat heights (i'm short legged), and prefer 15-16" BB heights.
     
  3. John, Its my contention that a BB is too high, seat too reclined, wheels too light, tires to skinny
    or anything for that matter, when it fails to meet the needs and or goals of the rider. Needs of
    the rider varies as does the amount of time they are willing or able put into adjusting to a "new"
    position to acheive a desired result. Some rule out higher BB bikes without giving them a fair
    evaluation. I initally had some discomfort, but after about 1K of trial and error I found the right
    combination of position and equipment to make both my LSRs (long slow rides) and my SFRs (short
    fast rides) delightful. Additionally, as some may have pointed out, going from a LBB to a HBB or
    the other way around after years of riding is gonna be a problem for most. Your body gets used to
    the position as do your muscles and it takes time for them to adjust. Some will never adjust! I
    ride high BB bike and thankfully I can comfortably ride one for miles of smiles. However, In my
    short recumbency of three or so years, all my bents with exception of my first bikeE have been
    medium to high BB SWB and LWB. So its what my bod is used to. If the low BB or any other aspect
    works for you? Why change it? If you do it could well result in a period of discomfort that may or
    may not go away. Greg Lemond touted bike designs that were more comfortable and contray to
    established racing designs, rode them to win two TDFs. Fast Freddy Markham is a world class LBB
    rider. 73 years old, GatorBob can cruise at 18 mph on his Ti Rush, faster than most on this NG 20
    years younger. IMO "performance" bike that inhibits the engines performance thru pain and
    discomfort is may well not be IMO a "performance" bike for that person. Too many lust after a
    performance bent that does not suit us...rather that make what suits us perform. My bent's better
    than my engine, likely it will always be.

    --
    Jude....///Bacchetta AERO/HED/Zipp St. Michaels and Tilghman Island.. Maryland Wheel Doctor Cycle
    and Sports, Inc 1-800-586-6645 "stratrider" <[email protected]> wrote in message
    news:[email protected]...
    > I joined the recumbent world in 1999 largely because I found that recumbent design accomodated the
    > human form! The bike fit the body rather than forcing the rider to contort to the bike! I still
    > ride a faired Stratus and find myself still loyal to the LWB, low BB design. While I have been
    > (and still am)close to adding a SWB to my lonely Stratus, I find myself drawn to SWB bikes with
    > only moderately high BB. Yet as I follow the evolution of recumbent design, I notice the BB
    > continues to get higher (ie high racers like the Strada). I guess my hope looking forward is that
    > new recumbent designers and manufacturers not completely forget ergonomics while in search of
    > performance. We already have sub 20 pound performance machines. It's just that they hurt too much!
    >
    > Jim Reilly Reading, PA
     
  4. Steve In Sc

    Steve In Sc Guest

    You have asked a very interesting question. Current high performance bents appear to favor a maximum
    BB/seat height difference of 9-11 inches. This height allows maximum power generation and allows the
    rider to be "rotated" back into a 23 degree recline for reduced wind resistance. I ride a Shock
    Proof, which has a 11 inch BB/seat height difference. The SP is much faster than my VRex. It took
    about a month of riding to become fully dialed in with the SP. I find the SP to be only slightly
    less comfortable than the VRex. Riders having problems with "numb" feet may not do well with a high
    BB. So, if you are looking for the fastest bent possible, a high BB bent with an extremely reclined
    hard shell seat is probably the way to go. If absolute speed is not your primary goal, you have a
    plethora of choices.
     
  5. PaPa's answer really is the right one... if it's uncomfortable, it's too high. I should add that a
    higher BB does take a little bit of getting used to, so if you jump on a bike with what you think is
    a BB that's too high, you might not be getting an accurate impression.

    That being said, though, the whole point of a high BB is to improve aerodynamics. If your heels
    don't protrude below your butt when you pedal, the BB is high enough.

    Note that the riding position rotates aft (but doesn't fundamentally change) the higher the BB gets.
    A rider on, say, a Speedmachine is in about the same position as the rider on a Gold Rush... just
    rotated a whole lot (if you don't believe me, go download some pictures and manipulate them).
    Therefore, a higher BB dictates a more steeply reclined seat back. If you don't recline the seat
    when the BB moves up, the riding position gets too closed.

    The real limiting factor is your neck. If you get so laid back that you can't comfortably breathe
    because your chin is shoved too far down in your chest in order to see the road, then you're too far
    back (and therefore the BB is too high).
     
  6. Jerry Rhodes

    Jerry Rhodes Guest

    Andrew Douglas <[email protected]> wrote in message
    news:<180520031819125595%[email protected]>...

    "If you get so laid back that you can't comfortably breathe because your chin is shoved too far down
    in your chest in order to see the road, then you're too far back"

    I have noticed something that is a corollary to this ....

    For us "benters" who are blessed with an "aerobelly", I have noticed that when I am reclined it is
    more difficult to breath because "belly breathing" is no longer an option. All of that gut that
    normally droops down and out is now pressing against the diaphragm. It is much easier to squeeze the
    olde tripe and force it into the diaphragm expelling air from the lungs than it is to suck it out
    letting air in. Expanding the chest wall is a minor part of really hard breathing. You really need
    to let all of that stomach and intestine full of powerbars, bananas, orange slices, oreos, gatorade,
    cytomix, jelly rolls, doughnuts and every other thing that is supposed to enhance performance (not
    to mention the grossly refluxed liver) hang out on the "intake stroke".

    I noticed how, when riding my wife's EZ-1 SC lite, breathing was far easier when riding hard than
    when I was riding the Vivo or the Dakota. Riding well below Vmax the percieved effort on all three
    is about the same. Above Vmax the EZ-1 is better by a large margin.

    Maybe in some other life my weight will match the "ideal weight" for my height. In the meantime I
    need to figure out how to grow 7", taller that is.....

    Jerry
     
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