Thoughts on Cycle Genius STX?

Discussion in 'Recumbent bicycles' started by Tracer, Jul 31, 2006.

  1. Tracer

    Tracer Guest

    I have a chance to buy one reasonably priced.($400).Any thoughts for a
    beginning recumbent?
    tracer2@charter.net
     
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  2. Tracer wrote:
    > I have a chance to buy one reasonably priced.($400).Any thoughts for a
    > beginning recumbent?


    While I have not ridden one [1], the price is reasonable in comparison
    to competing bikes.

    My only real caution would be is that the STX comes in only one size,
    and will either not fit or have to much weight on the real wheel if the
    rider is much over 6 feet (0.183 m) tall [2].

    [1] <http://www.cyclegenius.com/stx.htm>.
    [2] Assuming normal range body proportions.

    --
    Tom Sherman - Behind the Cheddar Curtain
    Post Free or Die!
     
  3. DougC

    DougC Guest

    Johnny Sunset aka Tom Sherman wrote:
    > Tracer wrote:
    > ....
    > My only real caution would be is that the STX comes in only one size,
    > and will either not fit or have to much weight on the real wheel if the
    > rider is much over 6 feet (0.183 m) tall [2].
    > ....
    > [2] Assuming normal range body proportions.
    >

    Yes but is a lightly-loaded front wheel on a recumbent so bad of a
    thing? During emergency braking much of the total weight shifts to the
    front wheel, and people frequently note that they crash because their
    front wheel begins to slide. Tires slide because either they are
    overloaded for what traction they have, or because they are overinflated
    for conditions.

    It seems logical to have weight distribution proportional to where the
    CG of the bicycle lies but in real-world terms it may be useful to have
    an "underweighted, underloaded, underinflated" front wheel in
    anticipation of making emergency stops.

    Cruising down the road with most of your weight on the rear tire doesn't
    hurt anything, but crashing when your front tire slides out under hard
    braking does. And certainly any bicycle can brake hard just fine on
    /clean pavement/,,,, it's when you need to brake hard while turning on
    a patch of gravel or sandy pavement that is the test.
    ~
     
  4. DougC wrote:
    > Johnny Sunset aka Tom Sherman wrote:
    > > Tracer wrote:
    > > ....
    > > My only real caution would be is that the STX comes in only one size,
    > > and will either not fit or have to much weight on the real wheel if the
    > > rider is much over 6 feet (0.183 m) tall [2].
    > > ....
    > > [2] Assuming normal range body proportions.
    > >

    > Yes but is a lightly-loaded front wheel on a recumbent so bad of a
    > thing?


    On a RANS Tailwind, I can amuse myself by doing power wheelies from a
    dead stop. ;)

    Too little weight on the front wheel can make handling during low speed
    riding, especially climbing difficult, particularly if the front wheel
    comes off the ground, as it did with every pedal stroke on my RANS
    Rocket when climbing the steeper part of this road. [1] [2] The late
    Gardner Martin reportedly did not put a larger than ISO 451-mm wheel on
    the front of Easy Racers, since obtaining proper weight distribution
    would have made an already long bicycle even longer.

    > During emergency braking much of the total weight shifts to the
    > front wheel, and people frequently note that they crash because their
    > front wheel begins to slide. Tires slide because either they are
    > overloaded for what traction they have, or because they are overinflated
    > for conditions.


    As long the the coefficient of friction remains relatively linear, the
    increased loading will produce a similar increase in traction.

    > It seems logical to have weight distribution proportional to where the
    > CG of the bicycle lies but in real-world terms it may be useful to have
    > an "underweighted, underloaded, underinflated" front wheel in
    > anticipation of making emergency stops.


    Assuming adequate braking power, one of two things will happen at the
    limit: the bike will rotate about the contact patch of the front tire
    or the front tire will slide. As long as the CG is some combination of
    far enough rearward and low enough that the front tire will slide under
    braking, no further improvement in braking will occur by moving the CG
    further rearward.

    > Cruising down the road with most of your weight on the rear tire doesn't
    > hurt anything,


    It will increase rolling resistance due to the greater deformation of
    the rear tire casing and resultant energy loss through hysteresis. The
    tire deflection could be reduced by increased tire pressure, but this
    is limited by tire blow-off and rim strength factors of safety, and
    ride comfort on non-suspended bicycles.

    > but crashing when your front tire slides out under hard
    > braking does. And certainly any bicycle can brake hard just fine on
    > /clean pavement/,,,, it's when you need to brake hard while turning on
    > a patch of gravel or sandy pavement that is the test.


    Generally, experience shows that LWB bicycles with lightly loaded front
    wheels are worse on loose surfaces than SWB bicycles with more heavily
    loaded front wheels.

    [1]
    <http://terraserver.microsoft.com/image.aspx?T=2&S=12&Z=16&X=581&Y=5541&W=2&qs=%7cperrysville%7cin%7c>.
    [2] The front wheel would likely have stayed on the ground if I had had
    a lower gear than the stock 39/28 or a 2001 or later RANS Rocket which
    has longer chain stays.

    --
    Tom Sherman - Behind the Cheddar Curtain
    Post Free or Die!
     
  5. DougC

    DougC Guest

    Johnny Sunset aka Tom Sherman wrote:
    >
    > Assuming adequate braking power, one of two things will happen at the
    > limit: the bike will rotate about the contact patch of the front tire
    > or the front tire will slide. As long as the CG is some combination of
    > far enough rearward and low enough that the front tire will slide under
    > braking, no further improvement in braking will occur by moving the CG
    > further rearward.
    >
    > .....
    >
    > Generally, experience shows that LWB bicycles with lightly loaded front
    > wheels are worse on loose surfaces than SWB bicycles with more heavily
    > loaded front wheels.
    >
    >


    As to the first point--on some bents it is possible to do this (lift the
    front wheel in low gears) but the "problem" of being able to lift a
    front wheel when your cranking up a hill in low gear isn't likely to
    cause you to crash to the extent that you get seriously injured. It's
    limited in scope (in that it's only a problem at VERY low speeds and on
    very steep hills) and is more of an annoyance than an actual danger.

    If you try to make an emergency stop and your SWB either lifts its rear
    off the pavement, or the front wheel slides out from under you--you are
    much more likely to be hurt.

    -------

    As to the second point--that's because most people seem to overinflate
    their front tires, regardless of what style bent they ride. They tend to
    go for the max pressure to minimize rolling resistance, but the tire
    ends up way overinflated for the actual load that is normally upon it.
    If you inflate your car's tires to 50 PSI, they'll slide around a lot in
    gravel, too. If you take one of those "poor handling LWB's" and air its
    front tire down to 50%-70% of whatever the rear is at, you'll probably
    find the loose-surface handling drastically improved.
    ~
     
  6. Jon  Meinecke

    Jon Meinecke Guest

    "DougC" <dcimper@norcom2000.com> wrote>
    >[...] If you take one of those "poor handling LWB's"


    In order of loose-surface handling, I rank mine from
    best to worst

    CLWB BikeE (wide tires)
    LWB Tour Easy (moderately wide tires)
    LWB Tour Easy (moderately narrow tires)
    Volae Sport (narrow tires)

    In addition to the (obvious) tire width aspect, the low-bottom
    bracket/upright seating may play a role.

    > and air its front tire down to 50%-70% of whatever the
    > rear is at, you'll probably find the loose-surface handling
    > drastically improved.


    Increased contact area may help if the issue is lateral traction loss.
    Suspension may also improve
    contact.
     
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