wheel work at above 30km/h?

[showdown]

Slightly off topic question-

What do the data say about aerodynamics in a peloton. That is, we all know the tests done on a sole rider but how effective are deep wheels when drafting and blocked from the wind on all sides... Is that a situation, in an 8-corner 40mile crit (1 mile laps, 320 accelerations out of corners) where the weight savings would be more beneficial than the aerodynamics? I am honestly really curious.

[Krackor]

an 8-corner 40mile crit (1 mile laps, 320 accelerations out of corners)

Let's assume each acceleration is from 20mph to 30mph. Quite a big acceleration, so this is going to be an overestimate.

From my math earlier, 150g rim weight difference means an additional 15 J of work for each acceleration from 20 to 30 mph. Assuming a 40 mile crit lasts 90 minutes, we can calculate average power cost of the rim weight over the whole duration:

15J * 320 / (90 min * 60 s/min) = 0.9W

320 accelerations in 90 minutes is once every 17 seconds. Add braking time to that and it sounds like this crit is almost entirely accelerations, so again we're overestimating here.

So let's say a conservative rule of thumb is 150g of rim weight = 1W power penalty in the absolute worst case. If you can trade 1W of aerodynamics for a 150g lighter rim then in this extreme case you might come out ahead. Anything less than that and you should choose the more aerodynamic and heavier wheel. All this is assuming a flat-to-rolling course. The equation begins to change as you climb more and your speed drops since the aerodynamic advantage diminishes, but it's also less likely that you will be putting in hard accelerations.

[audiojan]

Bora 50 would be a great choice. Others to consider would be ENVE 4.5 built around a stiff hub. I've found that stiff wheels are highly desirable during crit racing to handle the acceleration without any deflection.

[PLuKE]

This seems to be an interesting post, but now I feel somewhat confused.

I don't race, but I would like to try a local crit this year with my club, so maybe my post doesn't come into account.

I am looking for a lighter wheelset, and move away from my 80mm clinchers, it's pretty flat here, so when you guys say a heavier wheel will keep it speed better, at what speed? I ride either with a couple of friends and club rides, and usually flat, some short hills mixed in to, I sit around 18-20mph on the flat most of the time, would a lighter wheelset be better in this instances?

Luke

[wheelsONfire]

I read Alberto Contador was told by Zipp to use the 404 wheelset. They managed to sway him over on 303 but his mechanic said he liked 202 best.
Does this say anything?
I guess not, except possibly we all have different preferences.

If i rewind a bit. I swapped between a few of my wheels and i did and do notice, i forget how they are.

I ran CCU and Ax Stream 38 head to head. Sold CCU and bought Easton Aero 55.
Like the Aero 55 and used them all the time.
This season i ran Aero 55 a few times and swapped for Stream 38. To my surprise, now Stream 38 felt quicker and easier than i remembered.
I think Aero 55 might be a bit faster on the flats when speed is up. But honestly, i can not prove that.
It may be a placebo effect.
In effect, i would admit that i believe that the sense or feel is what gives most pleasure.
Because we adapt to things so fast and the gains could probably be discussed.

If i would have alot of money, i would probably give many people bikes and all that they needed for biking.
My only advice would be, get a bike that fit and buy that build which feels best.

I am convinced that if you feel at best on one build, this is the one you will perform best with.
I am not talking short track top speed. I aim at the full on experience and common use (what ever that is for you).

I don't think there is a right and wrong. This is simplifying things!
If you are convinced aero bikes and wheels make you faster and you want this, go for it!
If you are preferring something else, you should buy that.

Never underestimate the power of perception and passion. That is such a big boost in itself.

[kgt]

good post

[iliedanila]

Bora 50 would be a great choice. Others to consider would be ENVE 4.5 built around a stiff hub. I've found that stiff wheels are highly desirable during crit racing to handle the acceleration without any deflection.

Would you give me a f***ing break with Bora???
Those are *NOT* aero wheels.

Aero wheels are developed in the wind tunnel: Zipp, Enve, Reynolds...

Just because the italians decided after all this time to build a wider rim, doesn't make it aero..

Take a look:
https://intheknowcycling.com/2015/07/10 ... ke-wheels/

[junchen]

Bora 50 would be a great choice. Others to consider would be ENVE 4.5 built around a stiff hub. I've found that stiff wheels are highly desirable during crit racing to handle the acceleration without any deflection.

Would you give me a f***ing brake with Bora???
Those are *NOT* aero wheels.

Aero wheels are developed in the wind tunnel: Zipp, Enve, Reynolds...

Just because the italians decided after all this time to build a wider rim, doesn't make it aero..

Take a look:
https://intheknowcycling.com/2015/07/10 ... ke-wheels/

Don't be rude, and it's "break", not "brake".

Sent from my SM-G920I using Tapatalk

[ichobi]

They are aero wheels alright. They just arent the best aerodynamically but probably arent far behind. Griepel won 4 Tour stages last year and Dowsett broke the hour record on these wheels. Did't seem to slow them down one bit.


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[kgt]

A really good wheelset has to be torsioanlly stiff as well. Torsional stiffness test (2012) by roadbike.de site:

Zipp 303 Firecrest Carbon Clincher 15,7mm !!!
Bontrager Aeolus 5 D3 Clincher 6,2mm
Lightweight Meilenstein Clincher 4,2 mm

Zipp 404 2,7° !
Lightweight Standard III C 1,1°

[superdx]

Bora 50 would be a great choice. Others to consider would be ENVE 4.5 built around a stiff hub. I've found that stiff wheels are highly desirable during crit racing to handle the acceleration without any deflection.

Would you give me a f***ing brake with Bora???
Those are *NOT* aero wheels.

Aero wheels are developed in the wind tunnel: Zipp, Enve, Reynolds...

Just because the italians decided after all this time to build a wider rim, doesn't make it aero..

Take a look:
https://intheknowcycling.com/2015/07/10 ... ke-wheels/

Don't be rude, and it's "break", not "brake".

Sent from my SM-G920I using Tapatalk

Every time I see that site I cringe a little bit inside. In that particular post it's clear he's only got the Enve 4.5 rims to do testing with. The rest of the info are just specs pulled from the internet and put into an Excel and his opinions. All the other wheel sets he has done comparisons with are stock images. Definitely no dcrainmaker here with actual test data.

And would you look at this stem, holy cow. Can you really take advice from a rider that can't do a halfway decent bike fit?

[tikka]

Quoting intheknowcycling.com as an authority... LOL

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[audiojan]

Bora 50 would be a great choice. Others to consider would be ENVE 4.5 built around a stiff hub. I've found that stiff wheels are highly desirable during crit racing to handle the acceleration without any deflection.

Would you give me a f***ing break with Bora???
Those are *NOT* aero wheels.

Aero wheels are developed in the wind tunnel: Zipp, Enve, Reynolds...

Just because the italians decided after all this time to build a wider rim, doesn't make it aero..

Take a look:
https://intheknowcycling.com/2015/07/10 ... ke-wheels/

WOW! A bit testy there are we?! You're of course entitled to your opinion, but there's quite a few people riding and recommending the Bora's simply because they work extremely well. Wind tunnel tested or not.

[Krackor]

A really good wheelset has to be torsioanlly stiff as well. Torsional stiffness test (2012) by roadbike.de site:

Zipp 303 Firecrest Carbon Clincher 15,7mm !!!
Bontrager Aeolus 5 D3 Clincher 6,2mm
Lightweight Meilenstein Clincher 4,2 mm

Zipp 404 2,7° !
Lightweight Standard III C 1,1°

What practical impact does torsional stiffness have? I previously heard of studies or data attributing poor performance to a lack of torsional stiffness. I've often seen this article, which considers torsional stiffness to be a non-factor, referenced in wheel stiffness discussions and I've never seen anyone challenging that notion.

Does a 15.7mm torsional deflection translate into some amount of power loss, or time delay between pushing the pedals and tire pushing the road? How much?

[kgt]

I've often seen this article, which considers torsional stiffness to be a non-factor, referenced in wheel stiffness discussions and I've never seen anyone challenging that notion.

It is true that according to the article:
"In general, nobody talks about torsional stiffness – simple as that. Torsional stiffness varies little between wheels, and the small differences aren’t generally perceptible by a rider."
But roadbike.de proves that this is not the case. Unless slowtwitch considers 6mm vs 16mm of torsional deflection as a "little variation".
My experience with more stiff and less stiff wheelsets is that if you have a bike with a stiff front end (fork-headtube junction) a stiff a wheelset really makes a difference. If you have a flexy front end any wheelset feels similar.