Depends what IM you are going to do, any wind over 20km/h is going to wreak havoc especially when it comes from the side. As you live in SA I am guessing you'll compete at the IMSA in PE which is not known for it's calm seas and wind still days. Personally I would not recommend going with the 101's, especially if it's a road frame and clip-on bars. If you aren't going to ride over 40km/h (as others have mentioned) the benefit will be minimal. the amount of extra watts needed to keep those wheels turning in the wind will nullify any watts you'll save from the aerodynamics. It's my belief you'll get the most benefit from a 60mm in front and 80mm in the rear. I think you guys get Black Spade in SA? They make a 60/80mm combo for a decent price! Not even the Pro's (bar some when they know there will be no wind and a few others who enjoy them) ride with 101's on the front. Plus using 101's in a road race will be like wearing pink compression socks and slops at your local shopping centre. A serious no no but you might just get away with a 60/80mm combo. Spending that kind of money for one race a year would not be viable.
