SRM, Power Tap and many others are available. They're expensive,but a very objective way of monitoring your riding. Do you use one? Why? What kind?
SRM
PowerTap
Polar
Ergomo
Other
No
Don't need it - I'm too awesome
Don't really care, I'm just riding for recreation.
SRM
PowerTap
Polar
Ergomo
Other
No
Don't need it - I'm too awesome
Don't really care, I'm just riding for recreation.