WaveSounds

Hi there! I'm brand new to this forum, but am already impressed by the community here.

My question is this: I would like to beginning training this winter by putting on base/endurance miles (80% MAX HeartRate), but I'm debating about getting the Kreitler Challenger Rollers because of the resitance factor. This question is specifically directed to people who have rollers that are 4.5" in diameter. For putting on low HR endurance miles am I going to have to buy an expensive resistor unit, or will the top gears on my bike suffice?

Unrelated: Is there any easy way to find my actual max heart rate other than the (220 - Age) formula?

Thanks much, and I look forward to your responses.

Ted