[MENTION=433138]Lightning Fan[/MENTION]: Recently the Wahoo Fitness app has been finicky with the older speed and cadence sensors for my iPhone 4s. To get the app to recognize them I have to repeat this ritual every time:

• Be sure Bluetooth is enabled on the iPhone settings page.
• Open the Wahoo Fitness app.
• Tap on the sensors icon.
• Tap on the speed/cadence sensors icon.
• Navigate to the page of all the activities associated with the sensors. Be sure the appropriate activities are still checked (for me, it's cycling and indoor trainer). Sometimes I need to uncheck and reselect the activities.
• Backtrack to the main menu, then start up the app and activity as usual.
• The speed/cadence sensors are now recognized and display when I spin the crank.

PITA but it works. I only use the speed/cadence sensors with the iPhone at home, not on road rides. The iPhone battery doesn't last long enough for rides longer than an hour or so. The USB port fell apart on the ANT+ sensor case so I can't hook up an external battery to charge the device as I go. And it's too heavy and bulky for road rides anyway.

I may try a Bryton computer, which should interface with the Wahoo sensors, is much smaller and lighter than an iPhone and the battery should run much longer. Reviews are good and it costs well under $100.