Originally Posted by
merlinextraligh
I'm not sure you can extrapolate from single racers to tandems.
Part of the reason they're going to 25mm tubulars is that they have a good aerodynamic profile with wider rims, such as Zipp firecrests.
28mm tire on a convential (i.e. narrower rim) is going to have a significant aerodynamic disadvantage that you're not going to make back in reduced rolling resistance.
Hence if the goal is performance, you're ok with the ride quality, and you're not pinch flatting, I'd stay with 25mm.
I agree the wider 30mm tire will be less aero. There are always tradeoffs. Hills vs wind, group vs time trial. I suggest casting a wide net and trying a lot of different tires and see what you think works. I would only eliminate tires that others (that have personally used the tires) mention are slow. I would not assume they are slow because they are wide.
I do believe that Firecrest was optimized for 21-23mm tires.
Quote from Zipp FAQ:
Tire choice depends highly on user preference and conditions. To summarize, a 21mm has superior aerodynamics with our rims; a 23mm is larger and subsequently has better ride quality and rim protection, but at a slight aero penalty. Here are some questions you can ask that will help guide your decision:
Triathlon/Time trial? In general – 21mm.
Road racing? In general – 23mm.
Training and/or daily riding? 23mm+
Dry? 21mm at normal recommended pressure.
Wet? 23mm at a slightly lower pressure.
Smooth roads? 21mm at normal recommended pressure.
Rough roads? 23mm at a slightly lower pressure.
User prefers slight aero benefit of 21's at the expense of a little ride comfort, rim protection, and rolling resistance? Use 21mm.
User prefers slightly better ride comfort, rim protection, and rolling resistance of 23's at the expense of a little aero? Use 23mm.
Rider weighs less? 21mm.
Rider weighs more? 23mm.
Wider tires faster - Velonews
http://velonews.competitor.com/2012/...-faster_209888