Zipp 101 Alloy 700c Clincher Front Wheel in superb condition, spins buttery smooth and true with no hops or bobs. Works really great with 25c and larger tires though it is just fine with a 23c too.
The rim has a 30mm high cross-section with a fully toroidal shape. Toroidal? Funny you should ask: it means that the sides are curved rather than a straight V-section, and that curve reaches right across the braking tracks. Think ring doughnut and you'll get the idea. The rim bulges outwards from the hook bead, (where the tyre attaches) before heading back in towards the spokes.
This is technology Zipp have developed in the wind tunnel over many years. The idea is that, working with the tyre as the leading edge, the toroidal rim provides the best aerodynamics across the widest possible range of wind conditions. Get that? Basically, this shape reduces drag so you go faster. Zipp reckon this specific shaping allows the 101s to outperform much deeper section wheels that use straight-sided rims, without getting blown about in crosswinds. These are the only fully toroidal aluminium rims out there.
The 101s are pretty wide for aero wheels. The bottom of the brake track, for example, is 23.6mm wide while the maximum width of the toroidal section is 23.75mm. Why? Although skinnier wheels provide a good aero performance with ultra-narrow tyres, they're not so good if you use normal width tyres. So if you fit a 23mm tyre for better handling, you compromise the aerodynamics.
The 101s, on the other hand, are designed specifically for the kind of tyres that most of us actually use, from 21 to 35mm. Most people will doubtless use 23s - that's what Zipp sent us with the wheels. Fitting slightly wider tyres like these gives you more comfort, better stability and a reduced chance of getting a pinch flat - all good.
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