I'll add also that I wouldn't if your beater is heavy and there is a lot of prolonged at-your-limit climbing. I wouldn't ride my 27 pound beater (+11 lbs. versus my race bike) in local races with all out 10 minute climbs. There is already so much suffering on the lighter bike to stay near the front group as it is. If I'm going to suffer that much only to get blown out the back on a heavy bike I might as well stay home. I'd ride it in flat crits though.