Zipp Or Hed or what?? - Page 2

I can't give you a definitive statement of my criteria for choosing wheels at this point and the relative weighting of aero vs. power transmission vs. other issues. This is in part because I have just begun my research and selection process and won't reach a final decision until ~March of next year. So, right now I am collecting data and weighing the issues. I can tell you that I am only interested in the power transmission issue within my normal power range. Specifically, I could care less about the power transmission issue at >=500w because I don't plan to use 500w in TTs very often -- basically just acceleration off the line or coming out of any sharp turns. I also don't care much about power transmission off the saddle because I don't plan to be off the saddle much in my TTs. I absolutely require availability of power data, preferably with a PT SL hub. I have a reason for this, but can't go into details right now. Suffice to say that I plan to use power data for pacing and will tradeoff other wheel attributes in order to have power data. I realize that I can go with an SRM PM and then use any wheel, but a rear wheel would have to be very much faster than a PT alternative to justify the price of an SRM Pro.

We're talking about Hed and Zipps here - they're not run of the mill stuff. Would you honestly get a 10% variance in stifness/build quality between the 'gold standard' brands? I'd be surprised if there was that much difference (but i haven't viewed data so can't validate that statement). I would have thought the differences at the top bracket of wheels would be much smaller. Happy to be proven wrong and would be very interested in the data you're collecting - but am sceptical that you would be able to get a significant performance improvement on either Zipp or Hed, but as i said, happy to be proven wrong

Personally, i think you could throw a blanket over either Hed or Zipp - i don't think you could go wrong with either if you had the $$.

I questioned that myself. IMO, Stevfenton's comment seems to be a "Hey, look over there! <points>" response to RDO's request for some comparative data.

we are seriously collecting this data and workingon some tests that can be fair and compare like for like but I am very interested in what consumers prioritise for buying wheels

I'd say performance (aero, power transfer, and handling would all be aspects of this), cost, and durability would be the primary comparators to consider. Of those, performance would be my primary factor up until cost becomes a hard limit.

Having a unique differentiator, like Powertap compatibility or ability to use rubber brake pads, might be a very heavily weighted factor if it were something I was really interested in. That's going to vary by individual, however.

Well, I can give you a glimpse of how one consumer (me) looks at the wheels decision. I plan to have two sets of racing wheels, one for TTs and one for RRs. My criteria will include the aero characteristics in all realistic (0-25mph) wind conditions (I don't plan to have different wheels for different winds), weight, durability, maintenance requirements (truing, hub maintenance) and cost. I evaluate all decisions against a stalking horse option. My stalking horse option for TTs is the HED 3 carbon on front and the Zipp 808 on the rear. My stalking horse option would be HED 3s front and rear if HED offered the 3s with the PT SL hub. Why the HEDs? Because I have heard that the HED 3s are LA's favorite TT wheels and I think his research team is as good as anybody's. It's not that I idolize LA. It's that I think his team goes about equipment decisions very scientifically and they have the resources to acquire lots of data. So, I'm buying into the rigor of their process. I haven't decided on my stalking horse option for RRs. My criteria are probably not that different from other consumers except for my requirement for availability of a PT SL hub on the rear. I fully realize that many of the world's top TTers ride without PMs, but I think that is a mistake. I estimate that availability of power data alone is worth at least 10w and that translates to ~45secs on a flat 40K TT course. Power data plus an optimal power-based pacing strategy could add another 10w (~45 seconds). A wheel without a PT SL hub option would have to save me at least 1:30 as compared with the Zipp 808 to be considered. I think that's a tall order. If wheel builders don't get on the power train, I think they are making a huge mistake. The exploitation of power data for racing is still in its infancy, but that will change rapidly.

So any recommendations for good sites to get either new HEDs or Zipps for something OTHER than list price? I've not been too successful finding a decent price a set of Zipp 909s of late.

I plan to buy wheels from my LBS. But, it'll be a package deal for a TT frame, groupset, wheels and a PM -- maybe even an SRM Pro. So, it's just a matter of negotiating his margin for the whole package. I think I'll come out alright. I'm also considering renting wheels (e.g., discs) for specific races. There's so damn much money in wheels for such infrequent use. When I face that situation in other parts of my life, I try and rent.

The LA reference is a good point and one i often consider. Similarly, i don't idolise the guy (well, maybe not as much as some), but as you mentioned, he and his team do way more research and analysis into every aspect of bike racing/equipment than anyone else so there must be something in the HED's. (Out of curiosity, what do you think about the Bontrager Race Lites he also uses?)

Back to the point, the PT compatability will be a huge selling point when it comes time for me to upgrade, so on that point i may have to lean towards the Zipps (unless something changes). I am not convinced there would be much stiffness/performance differential between Heds or Zipps at my level. My LBS also highly recommends Reynolds wheels - don't know much about them, would be interested if anyone out there has tried them

Well, since Bontrager is owned by Trek, I would look at his use of Bontrager equipment with a bit of skepticism. But, I'm not aware of a financial relationship between Trek and HED. Somebody told me the HEDs are his favorite wheels. I'd look at the wheels he uses when it really matters, such as the Tour de France TTs.

Clearly, Zipp and Saris have a tight relationship, with Zipp openly promoting the PT hubs on its web site and making their wheels available with PT hubs for all but the discs. BTW, I understand that Zipp has a disc prototype with a PT hub, but haven't made the decision to market it. I think it's only a matter of time, hopefully to be resolved before my key races next spring and summer.

I don't have any knowledge of Reynolds wheels, but there's a disc I'm aware of that is interesting. I'll send you a link.

I am a jr aerospace engineering student and am actually looking at considering a topic such as this for my thesis. I had a look at the wind tunnel test data from the zipp site and the small amount on the HED site and it's really close you could actually throw a blanket over them; I have a cateye computer and a polar HRM so the Powertap does not sell the zipp wheels for me. However let’s look at a set of 808's from zipp



Pros:

Dimpled 81mm deep rim- dimples give a longer laminar (smooth) flow over the wheel hence reducing turbulence.

1395g (tubular)

Powertap option

draft legal - you can use them in road races!

Cons:

700c only



and the HED 3's - (Hed does not have to much data available)



Pros:

1500g

Low drag co-efficient

LA's Favorite wheel (that has to count for something.......right?)

Tri Spoke.

Cons:

Heavier than the 808's by 195g

No power tap





i think in the end they are both great wheel sets and are worthy of the money and it depends on your personal requirements but I think I’m leaning towards a combination of a Zipp 808 on the front and a HED3 on the rear...........maybe I’ll just by both sets and a disc to save the anguish of having to make a decision!

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Why Do I hit my hand with a hammer? Because it feels so good when I stop.

I did my final year thesis on aerodynamics for race cars - if i had my time again i would have done it on bikes. Do you need a wind tunnel 'dummy' to experiment on??

One point to note though - as anyone who owns one will tell you, the Power Meter is THE most important training aid. It's analagous to the 3rd dimension and provides a much more objective and specific picture of your performance and progress than either the HRM or computer could (there's numerous threads out there that talk on this subject). In conjunction with HRM, you'll be set - just about every pro out there uses one now thanks to LA and he doesn't use things if they don't have a benefit. I'm waiting till the new PT comes out that has coded HR and multiple storeage capacity. Being a fellow engineer, you'd appreciate the thrill of anlaysing numbers/data post ride

One point to note though - as anyone who owns one will tell you, the Power Meter is THE most important training aid. [/QUOTE]

what does the PT tell you just how many watts your putting out or a bit more than that.... any one from zipp or head or bontrager who wants to hire a jr engineer..................im free..........all the time

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Why Do I hit my hand with a hammer? Because it feels so good when I stop.

I knew there was a question on one of these threads that I wanted to get back to, but just remembered today that it was this one. The question of what is the value of a PM in a TT and how does that compare with the value of an aero wheel has a two-part answer.

The first part of the answer has to do with how well one paces himself with and without a PM and what the consequences (time) are of sub-optimal pacing. For this part of the answer, I'm going to simplify the analysis to that of a constant power pacing strategy. Whether we like it or not, at a moment in time we are all bound by a maximum sustainable power for a given duration. If we're talking about a 40K TT on a relatively flat course with little to no wind, we're talking about a duration of ~1 hr, plus or minus a few minutes. If we stick with standard terminology, this power number is FT (functional threshold). So, let's say our cyclist has an FT of 275w. He rolls up to the starting line with FT=275w that day and nothing he does will change that. The issue is how effectively he uses that resource to ride his fastest possible time. I assumed above that the cyclist's goal is constant power (CP) pacing. Without a PM, the most likely (highest probability) scenario is that our cyclist will ride the first part of the course at a higher power than he can sustain. This is the classic pacing error and is consistent with my personal experience. My own experience is that I tend to ride the first half of a TT ~10% above my FT. So, let's assume that our cyclist rides the first half of the course at 300w. With Andy Coggan's normalized power (NP) algorithm, we can then predict our cyclist's 2nd half power as 241w and an average power (AP) for the entire course of 270w (NP=275w). So, by riding the 1st half too hard, our cyclist has reduced his AP by 5w. The time lost compared with a CP pacing strategy is ~26 seconds. Given that Jim Martin has estimated the time savings of aero wheels (front and back) at these speeds is ~1:24 compared with a standard wheel with round spokes, I find it hard to believe that any rear wheel would save more than 26 seconds as compared with a Zipp 808 w/PT hub.

The second part of the answer raises the bar by considering variable power (VP) pacing strategies instead of CP pacing. Courses with varying grades and/or wind are all candidates for VP pacing and the more variable the grade and wind the greater the opportunity to save time by riding with a VP pacing strategy. This is true because the incremental use of power in sections of the course where bike speed is slow due to grade or wind or both results in a larger percentage increase in bike speed than a comparable decrease in power in sections of the course where bike speed is fast. If power/duration >FT was symmetrical with power/duration <FT, it would be a no-brainer decision about where and when to increase power (push) and decrease power (recover). But, we know from Andy Coggan's NP algorithm that it is not symmetrical. In fact, we pay a high price when we increase power >FT and we saw above that this results in a lower AP. Nonetheless, the optimal pacing strategy for most TT courses is in fact a VP pacing strategy. For our hypothetical cyclist with FT=275w, I estimate the benefits of VP pacing to be anywhere from 1%-5%, or ~36 seconds to ~3 minutes. Now, there's this slight problem of implementing a VP pacing strategy with or without a PM, but I would far prefer to have a PM if I was attempting to implement a VP pacing strategy.

What's with the "we"? Are you affiliated with the company you tout but forgot to mention that in any of your previous posts? Nice.