I recently got a Polar CS600 (mainly for its power meter) and found the new Wearlink transmitter strap was amazingly comfortable compared to my two old HRM straps. They are both the stiff plastic kind, and really uncomfortable. They don't conform well to my bony chest and if I wear them below the rib cage, they don't pick up my heart rate reliably, and they also gradually work their way down and eventually fall off, especially when I run.

The one that came with the CS600 is soft and stays in place no matter what I do. It would be excellent for running and in the gym, but it uses the 2.4 GHz wifi band, unlike the purely inductive (I assume so anyway) transmitters of the old style of HRMs (including HRM-compatible gym machines), so it only works with the Wearlink range of Polar units. And all of them are very expensive.

The CS600 unit is fine on the bike, but it's one hell of a ball and chain when you run, unless you just put it in a pocket and use it as a logger. But I want to be able to use it to pace myself better. Therefore, I need a transmitter strap that is soft like the new Wearlink ones, yet transmits a signal compatible with old HRMs.

I know that some older Polar straps were of the stiff kind, but someone told me that they recently made some that resemble the new Wearlink type, but without a user-replaceable battery.

Please help me find a suitable transmitter strap!