Sounds like the issue is more with those building the Zipp rims up?

Also, here's a shot of the infamous Cavendish wheel from the Tour de Suisse crash as it sits in my office (yes, he signed it for us). He rides standard rims on 16/20 lacing. The only non-stock item is the CX spoke in place of the CX-Ray.

The final customization to this sprinter's Venge is the wheelset, which has been built to be above all things, stiff. Starting with Shimano’s 7900 Dura-Ace hubs, team mechanics lace Sapim’s thick, round-butted Race spokes – 18 front and 24 rear – using radial and two-cross patterns to a set of Zipp 360 rims, as used on the popular 404 wheelset. The heavy gauge spokes, stout hub axles and angular contact bearings make for a base that’s both stiff and durable, according to mechanics. In the end though, the components are what Cavendish personally requested his wheels be built from.

Shrills aside, forget carbon clinchers and get tubulars if you want carbon. If you go tubulars go Enve Smart. Better rims and better hubs. Nobody does a good carbon clincher

http://www.cyclingnews.com/features/pro ... aren-venge" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
Doesn't sound like a stock build, but maybe he changed his mind this year?

Cav has been running 18/24 lacing on Dura-Ace hubs since way back when he was on Giant TCR all the way through Scott Addict, F01, Spec Tarmac then Venge. Mostly with 404's, sometimes with an 808 rear. If that wheel (pictured) was put on his bike it was a mistake by a mechanic with the obvious consequences. Looking at the Tour de Suisse photos though I'm nearly ready to say it's not the actual wheel in the crash, hard to tell though.

Martin,

I think you are confused between wheel lateral stiffness and how much does the rim moves between the brake pads.
Although they are more or less related, they are two very different values.

First of all, lateral wheel stiffness represents how much the wheel will deform under a load. This is basically how much you rim will move laterally, near the ground, when you stand on the bike. The stiffer the wheel, the lower the deviation of course. The stiffer the wheel, the better your accelerations (inertia apart).
Second, deviation between the brake pads is more or less the 180° rim deflection measured on a lateral stiffness bench. It is about 1/5th the lateral stiffness.

The wheel stiffness and the 180° deflection are working together through the spoking, the rim stiffness playing the most important role, the type of spoking has a good effect too.
The stiffer the wheel, the more deflection you will find between your brake pads.

This translates into 3 things:
1. your wheel is flexy: the rim deforms a lot near the ground, though this deflection does not translate as a deflection between the brake pads because the rim is flexy and somewhat "absorbs" the load. Also the spoking certainly can't hold the rim enough in place.
2. your wheel stiffness is quite standard, from moderately stiff to stiff: the deflection near the ground is not extremely low nor extremely high, but the rim is stiff enough to make a deformation too between the brake pads.
3. your wheel is extremely stiff: the deflection at the ground is very low, rim and spoking are very rigid too so the deflection between the brake pads is a quite high %age of it. Anyway you can't even perceive the brake pad rim deflection because it is too low.

From what you say, I can tell you the ZIPP 808 is from category 2. The other shallower wheelset is definitely from category 1 unless this is a very special rim.
Since you are a strong rider, you absolutely need wheels from category 3. Avoid wheels from category 1 for one reason: although they will deliver you a good stiffness perception, they won't be performant and won't come with a good durability because the rim moves too much left/right near the ground which will increase spokes fatigue.
Wheels from category 3 are basically stiff full carbon wheels like Mavic CCU, LW Sprints, custom wheels with deep/stiff rims and absolutely strong spokings (32 DT Competition).

Of course you must avoid the super light rims with standard drillings/spokings. Avoid the ENVE 25/45/65 rims because they are very flexy and only available with 20-24 spokings now. The same for Reynolds, though a 46 or 66 built with 28 or even 32 spokes as custom will be OK. Zipp rims, 303/404/808 are fine as long as they have a stronger spoking too: 28/32 or 32/32.

Please see our lateral stiffness bench, the pointer where the load is applied (similar to load near the ground) and the pointer at the 180°, translating the deflection between the brake pads.
What's interesting about wheel stiffness and perception of the stiffness is that we can tune both values depending on the spoking, the rim stiffness and the hub geometry.





Have a great week-end.
Adrien.
http://www.roues-rar.fr" onclick="window.open(this.href);return false;