Accurate assessment of the brake torque on a rope-braked cycle ergometer

R.S. Gordon, K.L. Franklin, J. Baker, B. Davies

Research output: Contribution to journalArticle

Abstract

A Monark cycle ergometer is a device globally used in physiological studies to measure the work and energy levels of exercising humans. In this paper a rope-braked cycle ergometer is examined to determine accurate measures of work and power. The work done is generally assumed, by physiologists, to be the load (masses suspended in a basket to apply tension to the rope) multiplied by the distance through which a flywheel braked by the load is moved (Åstrand). In this case the flywheel of the ergometer is designed such that any point on the circumference moves through 6 m for one complete revolution of the pedals. This is a simplistic approach and fails to take into account rope-brake theory and mechanical analysis of the brake mechanism. The dynamic coefficient of friction between the steel flywheel and nylon rope was determined experimentally to be 0.175. The physical dimensions of the ergometer brake system were taken and the theoretical brake torque calculated for a series of loads. It was found that this calculated brake torque was 10.8% less than the assumed brake torque. This error means that the work and power measurements obtained from the ergometer are overestimated by 10.8% for steady speed tests.

The braking force was measured experimentally using specially designed load cells to determine the tensions in the brake rope. The experimental results confirmed that the brake force is the same as that predicted using rope-brake theory and that the values of power and work used by sports scientists and physiologists are overestimated by approximately 11%.
Original languageEnglish
Pages (from-to)131-138
Number of pages8
JournalSports Engineering
Volume7
Issue number3
DOIs
Publication statusPublished - 1 Sep 2004
Externally publishedYes

Fingerprint

Exercise equipment
Torque
Brakes
Cycle
Flywheels
Circumference
Energy Levels
Friction
Steel
Nylons
Sports
Foot
Series
Cell
Experimental Results
Coefficient
Equipment and Supplies
Braking
Electron energy levels
Loads (forces)

Keywords

  • cycle ergometer
  • fitness assessment
  • flywheel
  • power
  • rope-brake
  • torque

Cite this

Gordon, R.S. ; Franklin, K.L. ; Baker, J. ; Davies, B. / Accurate assessment of the brake torque on a rope-braked cycle ergometer. In: Sports Engineering. 2004 ; Vol. 7, No. 3. pp. 131-138.
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Accurate assessment of the brake torque on a rope-braked cycle ergometer. / Gordon, R.S. ; Franklin, K.L.; Baker, J.; Davies, B.

In: Sports Engineering, Vol. 7, No. 3, 01.09.2004, p. 131-138.

Research output: Contribution to journalArticle

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