I've never tried one, but I felt too stretched out on a 52 Tarmac and the sales guy seemed to think it might be good with the shorter top tube, so as to not have to shorten the stem.
I'd rather be swimming...biking...running...and eating cheesecake...
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2008 Cervelo P2C Tri bike
2011 Trek Madone 5.5/Cobb V-Flow Max 2007 Jamis Coda/Terry Liberator
2011 Trek Mamba 29er