Posted: Sat Feb 11, 2012 6:46 pm Post subject: Wheel/tire combo
It seems that wheel companies are delving into the tire game, designing and building wheel/tire packages. This seems mainly to be a road thing, such as the Mavic Cosmic Carbone Ultimate wheel-tire system and the Zipp Tangente tires. My interest is this, I've got a Zipp Super-9 on order and was going to wrap it in a Conti Sonderklasse (I'm generally a Conti man), but the Tangente is basically a Vittoria with dimples and an aero profile. I've read good things about Vittorias on this forum, though I don't know which tire they base this on. Zipp claims that lift is generated when you pair the Super-9 with the Tangente. Anybody used these tires on the track? I'm going to be using them on outdoor tracks (primarily Giordana Velodrome in Rock Hill, SC which was getting measured by the UCI last week, by the way). I'm wondering about the balance between rolling resistance and aerodynamics when it comes to the tires. That forward lift may not have much effect in a 200 or kilo, but perhaps a small difference in a pursuit. Then again, I don't know the rolling resistance and weight comparison of the tires. I doubt it would make any difference or be a good idea on an indoor wood track.
I gathered some notes on tires from various searches here.
For Vittoria, the Evo Open Corsa CX gets some good reviews, as well as the Rubino Pro. The Michelin Pro Race also gets some good marks. On the Giordana velodrome the Conti's you like may still give good grip and low rolling resistance. I'll be trying Conti Sprinters on my race wheels there.
For the Tangente, Gotta question the lift theory as there is no place for a wheel/tire combination to produce vertical lift. However I could see the dimples helping with improved airflow with the transition to the wheel.
When they say that forward lift is created, from a physics standpoint what they mean is that the windward side of the wheel experiences a lower pressure than the leeward side. Essentially, they have the air moving faster on the side facing the wind and fast enough to overcome the vacuum created on the opposite side. It is lift that opposes the direction of wind travel and not direction of rider travel. There would be some benefit in the rider direction, though. This obviously doesn't work unless there is a crosswind of some angle, hence their claim of ideal wind angles (12-18 degrees). You aren't going to have that at an indoor track. And really, you may have that for only a small part of the time on an outdoor track. The more I think about it, the less I think that the aerodynamics of the tire are really going to matter.
Joined: Dec 16, 2008 Posts: 51 Location: Buenos Aires Home Track:
Posted: Sun Feb 12, 2012 10:03 pm Post subject:
I checked out Zipp’s Super 9 page. It begins:
PROPULSION IS POSSIBLE - All-Distance Rocket
"The Super-9 disc has an unassuming profile: It borrows from the perimeter shape that makes the Sub-9 so fast it can actually generate forward lift when paired with our Tangente tires."
Then it goes on to mention something about the “the Sub-9’s toroidal bulge”.
Apparently if you spring for both the wheel and the tire, it will actually propel you forward. Maybe not enough to make a huge difference on the track, but at triathlon distances... who knows?
Reminds me of the Burmese Gas Snake. It was a tube like thing you dropped into the gas tank that would give you a big increase in mileage.
There are many factors that go into an optimal track tire. Bilko hits on the biggest -- being sure you get good traction. Many of the tires optimized for rolling resistance or aerodynamics suffer from lack of grip on the track. The Sonderclasses are some of the best at this, along with the Veloflex Record and the Vittoria Evo Pista, so you certainly can't go wrong with your original choice.
We've tried a lot of the Vittoria tubulars on tracks and found widely varying results. The triathlon-oriented tires tend to be poor on the track. The Evo Crono is an exception, with very good grip and a great ride. Evo Corsa's are generally good but they aren't really made for track pressures so I've found that unless you get the very smallest diameters available, you get some wobble on bankings. There's a bit more structural stability in the casing design than you might think -- an Evo Pista weighs about 60% of what an Evo Corsa does, but at the same higher track pressure feels much stabler.
Rolling resistance becomes a very different discussion on the track. Higher pressures are necessary on the track to enable a stable casing. On some tracks you don't necessarily need cushioning in the tire, but remember that most tracks (especially local ones) can have cracks, asphalt surfaces, bumps, joins, and all kinds of other problems that need to be dealt with through your tires. So you have to compromise pressure with ride comfort and efficiency. Good track tires are amazingly supple and if you're on Evo Pistas or Sonderclasses you really can do things you can't do on a road tire. It's a small edge, but it's an edge.
In short, I wouldn't take all the promotional literature too seriously. This stuff has been around a while and you'll notice that track equipment doesn't change all that fast. Road tire and wheel technologies have been evolving but most of the issues aren't relevant to the track. Check with your local track about local needs, read the voluminous threads on this site, and you should be fine.
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