which 303 clinchers?

Honestly, if your rides are up and downhill then none of the wheels you mentioned will be faster over the course of a complete ride. The last generation before the Firecrest 303s applied a fair bit of the FC technology and aren't all that heavy.

The non fire feast version

I think my concern is to climb faster and not worry about coming down in speed.

Yes, but both bikes (presumably) weighed the same 6.8kg's, if Contdor was using light wheels then he'd have to put that weight on elswhere (heavy cassette would be an obvious one as you can then swap wheelsets without worying about droping under the weight limit). And going uphill at a constant speed heavy wheels Vs heavy everything else would be equal, they're only slightly different in accelerations.


Alternatively in an alternate universe as none of the activities mentioned below ever happened:

A good post from refthimos. Removing weight in wheels (particularly the rim), will be far more effective then removing weight elsewhere on the bike. When going uphill, and mainly steeper gradients, light wheels really do make tangible difference. They accelerate far more quickly and given that your pedalling style is not very smooth when going uphill generally, this means they hold their speed round your pedal stroke a lot better so you can pedal more smoothly and efficiently. As long as they aren't flexy, then they respond really well when putting in an attack too.

I'm talking from experience between Campagnolo Bora Ultras (not particularly heavy at 1350g), and Lightweight Obermayers (1070g). The difference is huge on the 10-20% climbs we have around here, the Lightweights are a true pleasure to climb, you feel like you float up these extreme gradients. The Boras however hold their speed much better on the flat - they seem a better all round wheel. The Lightweights kind of feel dead on the flat whereas the Boras feel dead on the hills. So for the same reason that light wheels feel fantastic on hills, I think the opposite is true when holding a high pace on the flat. These wheels have similar rim depths and although I think the rim shape does play a part in the difference, I think to some extent a lighter wheel will not benefit and in fact probably have some detrimental effect on holding your speed on the flat where the air is the real enemy. I find my pedalling style is not as smooth and efficient on the flat when riding Lightweights as opposed to the Boras.

However, please understand this is purely anecdotal and I don't actually know what I'm talking about.

Feel's faster or are faster though?

you're not accelerating though, you're climbing at a fairly constant pace.



Surely if they were light enough to make a difference then the heavy wheels would help your pedaling by propeling the bike through the deadspots and absorbing the energy as you push through the the 'good' bits of the stroke helping to "hold their speed round your pedal stroke a lot better".

And to put the acceleration argument to bed, what wheels do sprinter's (where acceleration is key) use?


ammended for my own use

spoon
remember weight helps you keep the tire rolling on the flats where only rolling resistance and aerodynamics are #1 in determining your speed. in the hills rolling resistance plays the same roll, but aerodynamics are not as relevant as the the lower speeds do not create the same wind resistance. on a climb you have to fight gravity, but the slopes are never 7% with no rise or decline. next time that you are on the road find a climb that extends over 2 miles and if you have a power meter try to keep your wattage fixed on a number that you feel comfortable holding for the 2 miles (300-400 watts). then try the same with a lighter set of wheels. inertia would have help if the gradient was constant, but geographical fromations are never constant, sometimes they change after a day.

Sometimes I think some forum members are confused about which forum they are posting on.

This is WEIGHT WEENIES, not "it doesn't matter how heavy as long as its aero" weenies.

_________________
Exp001

I reckon two things will help:

1. A few more hours training a week
2. A few less after dinner snacks! Think of it as weight weenie training for your body

...and FWIW I think the 303's are the perfect rim depth for almost all road race condition's because what goes up must come down!

This has me a little concerned. I focus on three things here:

(1) you want carbon clinchers
(2) you are considering the non-Firecrest version
(3) you seem to indicate that you like to climb but that you take the descents slowly.

Why am I concerned? Because if you prefer to descend slowly, that means you are going to be grabbing the brakes a lot, if not riding them for prolonged periods while you descend. That's not a great idea in general, but normally not fatal (I see guys doing this all the time while descending the canyons here in SoCal). BUT if you are doing this on carbon clinchers, particularly "previous generation" carbon clinchers (with Zipp, that means pre-Firecrest), then you are running a serious risk of overheating your rims to the point where the resin weakens and all that force your clincher tire is exerting on the rim bead will deform the rim and cause it to fail. This is not something that is a "theoretical" or "1%" risk - basically, if you consistently overheat older carbon clinchers, you WILL fry the rims at some point... Whether that's ride #1 or ride #10 all depends on exactly how much you're braking on them, but it WILL happen.

While I wouldn't recommend carbon clinchers to anyone who does steep or prolonged descents and uses a lot of brake doing so, at least the new Firecrests use a resin specifically designed to handle high heat. Same with the Enve SES wheels. But until a couple years ago, the manufacturers didn't really have an answer to this problem (other than to lay off the brakes!), so previous-generation carbon clinchers might not be the answer for you.

_________________
R5 VWD | 2008 SRAM Red | Rotor 3D+ SRM | Zipp 101s/Enve 3.4s
S5 Team | 2012 SRAM Red | Rotor 3D+ SRM | Enve 6.7s
P3C | Zipp Vuka Aero/R2C | Omega | FSA SRM | Zipp 808/Super 9 Disc
T1 | Scatto | Rolf Prima FX58

but if he is talking about zipp's pre-firecrest clinchers, then he is talking about an aluminum braking surface, so heat buildup and weakening of carbon fiber on the descent is a non-issue.

with a true full carbon clincher, the long descents definitely seem to separate the strong from the weak pretty quickly, but I have not heard of a single problem with zipp firecrest (or i think with the latest enve rims) on descents.

the only issue i have with my 303 firecrests is that i can't dial out the brake squeal, and am hoping that the new black prince pads from swissstop will quiet things down. braking power is not a problem, but the noise is a bit embarrassing.

Oops, I thought for sure that Zipp offered all-carbon clinchers before they went Firecrest, but I stand corrected. If you're going to take it easy on descents, then the aluminum brake track is probably the way to go. Then again, those wheels are going to be so heavy that they definitely won't be "Weight Weenies Approved"

_________________
R5 VWD | 2008 SRAM Red | Rotor 3D+ SRM | Zipp 101s/Enve 3.4s
S5 Team | 2012 SRAM Red | Rotor 3D+ SRM | Enve 6.7s
P3C | Zipp Vuka Aero/R2C | Omega | FSA SRM | Zipp 808/Super 9 Disc
T1 | Scatto | Rolf Prima FX58

If they are the Alloy rimmed ones then they are closer to 1600 gr...

That is heavier than my old school style training wheels - 32spoke Mavic Reflex, Record 11s hubs with DT... by about 200g
And I have heard of blowouts on the 404 Fire-crests, rim blowouts that is...

How reliable are the reports, have you seen any damaged 404 FC clinchers, and any pictures?

Good point +1

I still think the aero wheels are going to save more time on even a hilly ride than light wheels, as both bikes would still weigh 6.8kg unless you ignore the limit in which case light weigh wins beyond a point (whether that point is ~400g in the rims is a topical argument).

Some info that I found it at ffwd website

FFWD's focus is on fast, durable wheels. We don't consider weight to be of equal importance although we of course try to make the wheels as light as possible within the standards we have set.

Let's take a look at the forces that effect a system like a bicycle plus rider. If the conditions are; flat road, no wind, sea level and frictionless bearings, then the forces are rolling resistance, air resistance (frontal area) and wheels drag [1].

Some conclusions can be drawn from this graph:

* 1. The rolling resistance is constant. It depends on weight, tire and type of surface.
* 2. Both air resistance and wheel drag increase non-linear.

If you look at the formula [2] that calculates Drag Force, you can see that the speed v is squared. This means that when the speed of the system doubles, the Fd quadruples:
(1*v)^2 = v^2
vs.
(2*v)^2 = 4*v^2

And since Power (Pd) is Force x Velocity (Fd*v), the Power required to overcome the aerodynamic drag increases as the cube (^3) of the velocity. So, if you double the speed, you need eight times the Power, because you do four times the Work in half the Time.
Okay, now you should 'feel' the importance of lowering air resistance as much as possible if you want to go fast...forward.

But what about weight vs. aero?

Well, when you decrease weight (-10%), the rolling resistance decreases as well. But the lighter wheels usually also create more drag (let's say, +10% Cd, but this could easily be more), so that when you add the extra drag to the F4 and put the results in a graph [3] you can see that there is a certain point (break-even) where the weight becomes a less important factor than drag for higher speeds. In this example it is around 4.5 m/s (16.2 km/h).

When the drag is more than the assumed +10%, then obviously the break-even point will be at a lower speed -> the advantage of the lower weight will turn into a disadvantage even sooner.

Remember that in the beginning of the text I assumed some conditions to be constant or absent. For instance, no wind means that the air resistance acts directly from the front. It becomes a different story when there is a wind coming from a certain angle. This will influence the speed-power comparison very much and the aero characteristics of the wheels play an even bigger role in this case.

Same goes for the 'flat road' condition. If you are on a climb, the gravity plays a big part in the equation. As with the air resistance vs. weight, you also reach a break-even point (certain angle of the road) when the advantage of the lesser air resistance is gone because the climb becomes too steep (gravity pulls too hard on the weight of the wheels).