I think that depends upon the person and how they feel with being inside and riding. Remember that you always have to pedal on the rollers, and depending upon where you ride you may coast a lot more than you think you do. Once you keep at it, you can probably ride your normal distance and times.
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2007 Jamis Ventura Comp
2006 Jamis Explorer 2.0
2000 Specialized Hardrock (bought used)
Swim, Bike, Run and sounds like fun