Cycling Experiment: Measuring Torque of Bicycle Wheel

[australianschoolkid]

Hello
I have to complete an experimental physics project for high school physics this year and with help of the physics forum member, chroot (https://www.physicsforums.com/showthread.php?t=149893), I have come up with the idea of looking into a experiment like cycling physiological experiment with a heart rate monitor, like measuring power output at various heart rates.

I like this idea I wish to look into it more, but don’t have a power meter device (they work by measuring torque and wheel speed). I need a way of measuring torque, as I’ve been told torque x rpm = power. So we need to find a way to measure the torque of a bicycle wheel. I already have two types of trainers available (A trainer is a compact stand that attaches easily to the rear axle of your bicycle. The trainer holds your bike securely and provides pedalling resistance for your workout.)


The two types of trainers that I have access to are: a mag type trainer, which makes use of magnetic fields to generate resistance, and also have access to rollers, which consist of three revolving drums on which a bicycle can be ridden.


These trainers already include some kind of resistance device to load the cyclist. So by calibrating this resistance device I could find torque it requires to spin at a specific RPM.


The calibration would is the hard part, I need some way to apply a known torque and measure the resulting RPM. It has been suggested that use of an electric motor to drive the trainer's resistance could be an idea I can measure the motor's current consumption, and calculate its torque. If this idea was used, would I just attach the motor straight on to the wheel?, if so how?

So… my question is does anyone have any ideas of a way to find the torque of a bicycle wheel?
And does anyone else have suggestions / ideas on this experiment?



P.S. there is a rundown on the types of trainers on this website-
http://www.bikeline.com/feature/trainer/index.htm

 

[anathema]

Hello and thank you for sharing your project idea with us! I find your experiment very interesting and I would be happy to offer some suggestions and ideas for you to consider.

Firstly, I think your idea of using a heart rate monitor to measure power output at different heart rates is a great way to investigate the physiological effects of cycling. However, as you mentioned, you will need a way to measure torque in order to calculate power.

One possible solution is to use a strain gauge. A strain gauge is a device that measures the strain (or deformation) of an object under a force. In your case, you could attach a strain gauge to the axle of the bicycle wheel and measure the strain as you pedal at different resistance levels. By calibrating the strain gauge, you can then calculate the torque applied to the wheel.

Another option is to use a dynamometer, which is a device specifically designed to measure torque. You could attach the dynamometer to the axle of the wheel and measure the torque as you pedal. However, this may be a more expensive option.

As for using an electric motor to drive the trainer's resistance, this could work but you would need to make sure that the motor is able to provide a wide range of torque levels for your experiment. You could attach the motor to the wheel using a belt or pulley system and measure the torque using a torque sensor.

I hope these suggestions are helpful to you and I wish you all the best in your experiment. It's great to see young scientists like yourself exploring and experimenting with physics concepts. Good luck!

 

[m2003]

Hello,

It sounds like you have a very interesting experiment in mind. Measuring the torque of a bicycle wheel is certainly a challenging task, but with some creative thinking and experimentation, it is definitely possible.

One idea that comes to mind is using strain gauges. These are sensors that can measure the strain or deformation of an object, and can be used to indirectly measure torque. You could attach the strain gauges to the frame of the trainer and measure the strain as the wheel rotates. By calibrating the strain gauge measurements with known torque values, you can then calculate the torque of the bicycle wheel at different speeds.

Another option could be to use a dynamometer, which is a device specifically designed for measuring torque and power. You could attach the bicycle wheel to the dynamometer and measure the torque as you pedal at different speeds.

As for using an electric motor to drive the trainer's resistance, it is possible but it may require some modifications to the trainer. You would need to attach the motor to the trainer's resistance mechanism and then connect the motor to a power supply. You can then measure the motor's torque and use that to calculate the torque of the wheel.

Overall, I think your experiment has a lot of potential and I would encourage you to explore different options and techniques for measuring torque. Good luck with your project!