JAMES_AMTRAK

So I usually I race with 420 aeros for crits, but don't have acess to them this week. So my choices are to use my bontrager race wheelset which is about the same rim depth as some 202s or a set of zipp 404 with the aluminum brake area. That are 58mm. I weighted them both and the zipps are just a few tenth of a ounces lighter than the bontragers. It just seems its harder to spin those 404s up. So here's the question, what wheels would you use. Is it gonna be more difficult to spin up the 404s or is it gonna be bettter to use them for aero advantages? It is a crit so I guess spinning them up contsantly would be of importance.

The course is 4 corners, flat with long straight aways

pdedes

will you be in the breaks, or will you ride around in the back. if you're sticking your nose in the wind, get aero, if not don't worry about it.

rangerdavid

^^this^^

rangerdavid

....and don't race anything you can't afford to replace. I'm just sayin.......

JAMES_AMTRAK

Well it is Cat 5 so there probally wont be any breaks. looking at a smallish field maybe 20 riders. i get on the 404s they seem harder to accelerate with but you guys know better than i do

ravenmore

Don't race Zipps in Cat 5 ever.

asgelle

https://www.biketechreview.com/review...el-performance

JAMES_AMTRAK

lol. thats funny. They feel so hard to spin up. a couple more races and im outta 5s anyways.. was really wierd when i seen zipp 404s i though okay the rim depth will be in the 40mm range. hell no their 58 mm. cant be good for crits can they

JAMES_AMTRAK

wow thats good reading. So what it is saying is that acceleration is not very significant or important as the aero dynamic advantages of the wheelset. So even though its a crit with lots of accelerations IM not gonna notice a difference in the 2 wheelsets but i will notice and benefit for the aerodynamics of the 404s. thanx

BarryJo

It's the 5's, I'd be more concerned with other things than what wheels to ride.
edit: what race are you doing?

carpediemracing 

Lighter and more aero wheels - I'd select the set that has both, the 404s (based on your initial post).

In general if your avg speed is under 25 mph or so, or you have to accelerate a lot in a race, lighter wheels are better. If you spend a lot of time at speed (30-35 mph), even just a minute or two at a time, then aero becomes pretty significant.

In races I generally use aero wheels (60mm/tubular); the wheels happen to be the lightest wheels I own.

In training I generally ride best with light but non-aero wheels, since avg speeds are down 5-7 mph and since I actually have to climb more than 20 seconds at a time. For training purposes I'll use heavier aero wheels (clinchers), but I get shelled easily on hills and after repeated accelerations.

I've been destroyed by Cat 1s on 18 pound bikes with non-aero aluminum clinchers. I've also shelled riders with lighter bikes, faster wheels. Ultimately it's up to the rider; equipment helps only slightly.

JAMES_AMTRAK

Okay so my training wheels and the zipp 404s weight the same. Because the 404s are 58mm with aluminum frame clinchers am I gonna get shelled trying to spi. Them up or should I go with ny training wheels.

zigmeister

If you were racing the Pro/1/2, I would say aero. But for a true Cat 5 in Florida, assuming Bartow today, I wouldn't worry about it. Wheels aren't going to make a bit of difference.

Oh, and you think nobody is going to break away, Florida always have people that are sandbaggers, or just "passing through" the ranks on up. Since this is the Bill Bones series, I am going out on a limb and thinking there are going to be 4-5 guys that are real strong, and probably will be in Cat 3 in the next year or so in that group..haha.

Good luck, just go ride and stay out of trouble.

Oh...and if you choose the Zipps, either remove the decals, or you better finish top 3.

hammy56

doesnt matter.

justkeepedaling

You need a skinsuit and shoecovers now

Homebrew01

If the Zipps weigh the same, and are more aero, how could they possibly be slower to accelerate ? Unless the bearings are shot.

carpediemracing 

Rim weight vs hub weight. Or tires or cassette etc.

asgelle

In theory perhaps, but in practice what kind of times or distances are we talking about? Nanoseconds? Microns? We know that a 50% change in moment of inertia, results in only a 0.019% change in power for a crit. Again, that's 50 compared to 0.019, a factor of less than 1/1000th.

gerundium

think about it this way:

M = I*A

M = the moment (Torque) applied to the wheel.
I = moment of inertia
A = angular acceleration.

The moment of inertia is defined by the square of the distance of the mass from the center. So if both wheels are the same weight they can still have a wildy different I depending on the way the weight is distributed. the weight of the hub is important here, for a very similar hub weight and size the zipps should have a lower I. That is because if the hubs are similar together with the spokes the rims are the same weight but the zipps are higher and will thus have a lower radius.

asgelle

Like I said, how big an effect do you think this is? Spinning a wheel up isn't only a matter of moment of inertia. There's still aero drag and bearing friction. Put in some numbers and see how trivial acceleration effects truly are.

carpediemracing 

I think that significantly lighter wheels/tires helps a lot when accelerating hard. I can't prove it though, since I don't know enough math/physics. "A lot" can be gaining just a few feet in 5 or 10 seconds, accelerating from ~20 mph to ~35 mph.

Unfortunately racing is not just about average power. It's also tactical/situational. If I have to do an extra downstroke to get to speed, or the extra 800 grams of rim/tire weight forces a rider to leave an extra foot or two gap, it costs precious reserves to get back into the draft. If a racer has to average just a watt over their exploding point for that race (whatever that is on that day etc), they're out of the race.

At the same time, as I pointed out earlier, equipment only helps a little. The engine (and its brain) is more important.

svtmike

This must be an important crit with a lot on the line to be considering running a set of Zipps over a set of Bontragers.

Dean V

How much is the prize money?

yongkun

Seriously, it doesnt matter at all.

gerundium

those effects are indeed encompassed in the M term. i had some classes in fluid mechanics but i don't have a clue how to quantify the aero drag on moving wheels. What i can say is that the aero drag is probably by far the most important force in this case due to the far distance from the center axle (bearings are very close to the axle).

All i was trying to say with that post is that if you have about equal hub size that aero wheels probably have smaller moment of inertia making them easier to spin up.