Ibis' 742 rim builds upon their successful 741 rim, boasting several new improvements and refinements. As with the 741, the 742 retains the same 41mm outer/35mm inner rim widths. The 742 features a lower cross section height for better impact resistance. The carbon layup has also been improved, combining layers of a new super tough carbon/eopoxy prepreg with their original carbon composite. Ibis has also introduced an asymmetric design that features 5mm of offset, allowing for higher spoke tensions that are nearly equal on both sides of the rim. As a result of all this, the 742 rim nets a 30% increase in impact strength while managing to decrease in weight by 7.5%, compared to the previous 741 rim.
ADVANTAGES OF WIDE RIMS
A wider rim delivers better sidewall support so in many cases you can run lower pressures in your rubber. Tires mounted on wider rims don’t burp as easily. Lower pressures, even a pound or two, do several beneficial things, including increasing the contact patch, which results in better traction. Running lower pressures on varied terrain actually reduces rolling resistance. Wider rims are stronger and stiffer. With increased traction comes increased braking control.
The 742 rims are ideal for ultra low pressures (10-18 psi) with 2.8+ tires (or 18-25psi for 2.25" - 2.5" tires). The folks at Ibis have found very positive results running any the 742 rim with the new current crop of 2.8"+ tires from Maxxis, Schwalbe, and WTB.