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  • Summary: Crank/Pedals for Force/Power Measurements

    Below is a very large summary of the responses I received to the
    following questions. Thanks to everyone for the advice and
    large list of references and resources.

    Sincerely,

    Shane K. Best
    skb@utk.edu

    On Wed, 3 Apr 1996, Shane K. Best wrote:

    I have a question regarding bicycle pedals and/or cranks that can be used
    to measure forces exerted by the rider and/or power output. If such a
    device exists, I would appreciate advice in regards to where such an
    instrument can be purchased. Also, can the data retrieved be stored
    and somehow downloaded to a computer?

    ************************ Summary of Replies *********************

    Shane,

    Our lab has developed several 2D and 3D pedal dynamometers to
    measure pedal forces and moments. We have built dynamometers for other
    labs but I don't think you will find them readily available
    commercially. We have built them primarily for lab use with the data
    acquisition performed with a PC. But we have recently built a mountain
    bike (SPD) dynamometer designed to be used outdoors with a portable data
    acquisition system.
    The advantage of using a pedal dynamometer rather than
    instrumenting the crank arm is the information you have regarding the
    pedal forces. You can still compute crank torque and thus power but you
    also have the pedal forces available for more complex analyses.
    I hope this helps. Let me know if you have any other questions.

    -Rick

    __________________________________________________ _____________________
    Richard R. Neptune
    Biomechanics Research Laboratory
    University of California, Davis
    Davis, CA 95616
    Tel: (916) 752-2235
    Email: rrneptune@ucdavis.edu

    Shane,

    The device you want is SRM. It's made in Germany and costs about $4000. It
    does everything you want and is very accurate. Contanct SRM Training System
    by phone 49-2463-3156 or fax 49-2463-3090.

    Good luck,

    Jim Martin

    /////////////////////////////////////
    / Jim Martin /
    / University of Texas at Austin /
    / j.martin@mail.utexas.edu /
    / 512-495-9339 /
    /////////////////////////////////////

    Shane,

    I don't know the name but I have heard of a "new" system that measures
    power and force per crankarm. I read about it in VeloNews - try looking
    there or contacting the publisher.

    good luck,

    dj

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%
    % %
    % Dan A. Johnson (d-johns1@students.uiuc.edu %
    % Rehabilitation Engineering %
    % Univ. of Illinois %
    % 309 E. John St. (217) 328-6777 %
    % Champaign, Il. %
    % 61820 - 5679 %
    % %
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%

    Shane,

    I came across a paper written by G. Alvarez. I haven't read it so I
    don't know if it will help you or not.

    Title: A new bicycle pedal design for on-road measurements of cycling forces
    Sourc: Journal of Applied Biomechanics Feb. 96 v.12 is.1 pp. 130-142

    Hope this will help you out!

    Brad Capstick
    x92xkb@juliet.stfx.ca


    Shane,

    We have been pondering on a similar problem here in the Memphis
    campus. The best we could get was a dynamometer-equipped exercise machine
    which also gave the power output. You may cantact Faunne Anderson at
    (901) 448-6535. She had been dealing with the problem since I left off.

    -Debarag Banerjee

    Shane,

    get in touch with Hartwig Distler (mad@mpik-tueb.mpg.de).
    He is using a device like the one you described in a VR-setup.

    Dietrich Opitz

    MPI fuer biologische Kybernetik
    Spemannstr. 38
    72076 Tuebingen
    GERMANY

    Tel: ++49(7071) 601 606
    FAX: ++49(7071) 601 575
    e-mail: dio@mpik-tueb.mpg.de

    Shane,

    Try looking for papers by Maury Hull (usually listed as ML Hull) at UC
    Davis. You may also try contacting him directly at (916) 752-6220.

    Joel

    *****************LIFE_IS_NOT_A_REHEARSAL********** *******

    Joel M. Bach, Ph.D.

    UC SanFrancisco Ergonomics Program
    1301 S. 46th St Bldg. 112
    Richmond, CA 94804

    Phone510)231-9448 Fax510)231-9500

    www.me.berkeley.edu/ergo/joel.html

    *****************Another_Friend_of_Ishmael******** *********

    Shane,

    I took a part in such an experiment at NASA one summer, but we had to
    instrument the bicycle ourselves with load cells and develop the
    software with Labview to collect the data. You should contact Dr.
    Fernando Figueroa at the University of New Brunswick who developed the
    system. He may be willing to send you copies of his reports and
    papers. His e-mail address is figueroa@unb.ca.

    Beth Todd

    Dr. Beth A. Todd
    Assistant Professor
    Engineering Science and Mechanics
    Box 870278
    University of Alabama
    Tuscaloosa, AL 35487-0278
    btodd@coe.eng.ua.edu
    (205)348-1623
    fax: (205)348-7240

    Shane,

    You may want to contact the following professor at the Univrsity
    of Illinois:

    ----------------------------------------
    name: klein richard e
    phone: (217) 333-3299
    address: 354 meb, MC 244
    : 1206 w green
    : urbana, il 61801
    department: mechanical & industrl eng
    title: assoc prof of mech eng
    email to: r-klein@uiuc.edu (r-klein@ux1.cso.uiuc.edu)
    ----------------------------------------

    Brian

    Shane,

    Try contacting Bob Gregor at Georgia Tech. He not only uses them
    regularly, but he has designed different versions for measuring forces.
    His e-mail address is:
    bob.gregor@oip.gatech.edu (Bob Gregor)

    good luck,
    df
    __________________________________________________ _________________
    Dan Ferris
    UC Berkeley Biomechanics Laboratory
    103 Harmon
    Berkeley, CA 94720

    (510) 642-8662
    dferris@uclink2.berkeley.edu
    http://garnet.berkeley.edu/~hbbiomxl/dferris/

    Shane,

    You are asking for a device that sounds simple but is complicated.
    Measuring the power output of a cyclist easy, measuring pedal forces will
    require some very special components.

    I would suggest a strain gage array on the pedal crank. The power for
    these strain gages depends on how the data will be transmitted. One can
    either employ some type of sliding contacts that will allow electrical
    current from circuits on the spinning crank power supply and data
    aquisition equipment that is not spinning, i.e. on the frame.
    Alternately, one could develope a completely telemeterized unit in which
    the strain gage output is communicated to data aquisition equipment
    without wires. Such systems have been used in implantable orthopedic
    devices to track in vivo loads. One recent reference on the subject is:

    Rohlman et. al. Telemeterized Load Measurement Using Instrumented Spinal
    Internal Fixators in a Patient with Degenerative Instability, SPINE 20
    (24) pp 2683-2689.

    My intuition tells me that these systems are veeerrryyy expensive. The
    sliding contact idea seems feasible, though you would need output from at
    least 6 gages. That is 12 leads plus two power supplies that need to be
    communicated accross the contacts.

    I have no experience with these devices, just thought I would pass along
    some ideas.

    Hans Hoffman, MS
    Yale School of Medicine

    Dear Shane,

    Regarding force pedals, please refer to the following publications;

    1. Broker JP, Gregor R. A dual piezoelectric element force pedal for kinetic
    analysis of cycling. International Journal of Sport Biomechanics 6: 394-403,
    1990.

    2. Gregor RJ, Broker JP, Ryan MM. The biomechanics of cycling. Exercise and
    Sport Sciences Reviews. Vol. 19, pp. 127-169, 1991.

    3. Gregor RJ, Wheeler JB. Biomechanical factors associated with shoe/pedal
    interfaces: implications for injury. Sports Medicine 17 (2): 117-131, 1994.

    4. Wheeler JB, Gregor RJ, Broker JP. A dual piezoelectric bicycle pedal with
    multiple shoe/pedal interface compatibility. International Journal of Sports
    Biomechanics 8: 251-258, 1992.

    5. Wheeler JB, Gregor RJ, Broker JP. The effect of clipless float design on
    shoe/pedal interface kinetics and overuse knee injuries during cycling.
    Journal of Applied Biomechanics 11: 119-141, 1995.

    Also, the latest issue of Cycling Science featured an article on the US
    Olympic Cycling movement and discussed the use of these pedals. Regarding
    the force pedals mentioned in these publications; two pairs and a single
    pedal were made by the group at UCLA (Gregor, Wheeler, Broker et al.) and
    now one pair is at the US Olympic Training Center (see contact person below)
    and one pair is at Georgia Tech under the direction of Robert J. Gregor,
    Ph.D. The single pedal made was formerly at U. Maryland but I think (?) is
    now at UMass with Graham Caldwell, Ph.D.

    Regarding a crank power device;

    You may want to consider the SRM device. A starting point would be to
    contact Jeffrey P. Broker, Ph.D. sport biomechanist at the US Olympic
    Training Center in Colorado Springs and inquire about the SRM (also your
    contact at the USOTC regarding the force pedals). You may have seen or
    heard of this device in some bicycle publications, scientific journals, etc.
    but Dr. Broker has been intimately involved with the SRM's introduction to
    North America (I believe it is German manufactured) and has experience using
    it with the Olympic cyclists on the track, in the windtunnel, and on the
    road. You may recall that in the past Greg Lemond and others used this
    device to train and monitor some race performances. Anyway, I think its what
    you are looking for and rather than list all the specs and possibilities
    here, contact:

    Jeffrey P. Broker, Ph.D.
    US Olympic Training Center
    Sport Science & Technology Division
    One Olympic Plaza
    Colorado Springs, CO 80909

    Phone (719) 578-4588
    Fax (719) 632-5194
    email jpbiomch@ix.netcom.com

    Good luck. You will probably receive a response directly from Jeff Broker
    anyway.

    Sincerely,

    Jeff Wheeler

    -------------------------------------------
    Jeffrey B. Wheeler, M.S.
    Biomechanics Research & Consulting, Inc.
    840 Apollo Street, Suite 218
    El Segundo, CA 90245

    Telephone: (310) 615-3112
    Facsimile: (310) 615-3038
    emial: brccal@ix.netcom.com
    -------------------------------------------

    Shane,

    There is a guy in Holland who produces (or did produce) such a device.
    The cranks have sensors on them that are picked up by a handlebar
    mounted device that has a display that gives the rider on the
    spot info as well as storing the data to be downloaded to a pc
    at the end of the ride/race/training session.

    I saw the info in them 2 years ago in VeloNews. The article
    expose'd how Greg Lemond was using it to get himself into
    shape for that year.

    Not much has been heard of them since.

    The units are quite expensive... $5300 then... which included
    the inventor personally installing the equipment.

    If interested I can see if I can find the back issue. It
    would take a bit though and no promise that I would be able
    to find it.

    -Cody
    codypy@farallon.com

    Shane,

    I am doing research here at UC Davis using a six-load-component pedal
    dynamometer to measure forces and moments at the pedal. It was here long
    before I arrived, but it was made by Shimano Industrial Corporation of
    Osaka, Japan. (Model PD-001) Please reference papers by ML Hull from the
    early 1980's for more information. Hope this helps.

    Shawn Sobelman, PE

    Shane,

    I got this from a bicycle mailing list. I thought you might be interested
    in contacting Utopian Designs, which produces a data acquisition network
    called StressNet. I know they have used it for measuring the stress in
    things like handlebars, so I'm pretty sure they could come up with something
    for you. It can even be used in a wireless setup, so you can do road tests
    (they have used it for OFF-road tests of mountain bikes) It produces digital
    data in a spreadsheet compatible format.

    Contact info:

    Utopian Designs
    4077 Ebony Terrace
    Victoria, BC V8N 3Z2
    CANADA

    Tel: (604) 477-4839
    FAX: (604) 477-1487

    email: utopian@islandnet.com

    Shane,

    I recall seeing such a setup at the USOC traning center in Colorado
    Springs a few years ago. I think they had to build it themselves. You
    might contact Dr. Sarah Smith, the biomechanist there. She may be able
    to answer your question.

    Leon.

    ************************************************** ***************
    Leonard G. Caillouet 57840 Homestead Drive
    Graduate Student Plaquemine, Louisiana 70764
    Department of Kinesiology
    Louisiana State University
    Baton Rouge, Louisiana e-mail: lcaillo@unix1.sncc.lsu.edu

    "The world may not end in catastrophe. There are at least two
    other possibilities, paperwork and nostalgia." -Frank Zappa
    ************************************************** ***************

    Shane,

    Check out the leatest Journal of Applied Biomechanics Winter 1996.

    Gene Jameson
    Sport Science and Technology
    United States Olympic Committee

    Shane,

    I don't know of any commercially available pedal instrumentation, but
    here are a few references you might find useful:

    ML Hull and RR Davis,
    Measurement of pedal loading in bicycling: I. instrumentation.
    J Biomech, (1981) V14(12):843-856

    J Newmiller, ML Hull and FE Zajac,
    A mechanically decoupled two force component bicycle pedal dynamometer.
    J Biomech (1988), V21(5): 375-386

    JP Broker and RJ Gregor,
    A dual piezoelectric element force pedal for kinetic analysis of
    cycling (1990) International Journal of Sports Biomechanics
    V6(4):394-403.

    Thanks,
    Danielle.

    $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$
    Danielle Toutoungi,
    Oxford Orthopaedic Engineering Centre,
    University of Oxford.
    tel: ++ (0)1865 227684
    fax: ++ (0)1865 742348 email: danielle.toutoungi@eng.ox.ac.uk

    "Time flies like an arrow, Fruit flies like a banana" - Anon.
    $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$

    Shane,

    I have an article in front of me in Cycling Weekly (UK mag) from July 1 '95
    (the Tour Special issue).
    It's about "SRM Power Cranks".

    It say's "German developed SRM Power Crank System" in the article. And that
    Gewiss (the road race team) use them in early season training.
    Cycling Weekly's phone number is +44 171 261 5588

    CW quote an email address: snowdons@cix.compulink.co.uk
    BUT it's down as "race round-up", but you could try enquiring..

    It says "..signals are transmitted to the handlebar-mounted mini-computer,
    which then calculates power output... which can be printed out in graph
    form for analysis".
    Doesn't say how exactly.

    Hope this gives you something to go on.

    Tony.
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