Doge

I'm not challenging folks credentials or lab tests, but I saying I have not seen data on pack riding - as I assume its real hard to get. I also don't see tests introducing random wind conditions gusting etc., the data I see is based on repeatable experiments with controlled conditions and calculations by smart people, but not so much how my kid rides.
Pros - Sagan was on both a Venge and a Tarmac @ ToC. All riders have a choice where the weight is located. I'd prefer to put a lead weight on the BB than have it in the rims. My son says a bike feels lighter when the weights are low - comparing two bikes the same mass. Froome - the year he won the TdF had 800g wheels (SRT-24) and weight on the bike for climbing stages. There are many USA Cat 1/2/3 amateurs that need to ride under UCI rules, not just pros. My focus is on the juniors, but same with the U23 and same with masters worlds (I think).

I did the video below (posted already I think) on one of the first tests we testing the aero vs. weight thing. We found for my son's riding light 50mm profiles better for him in every real riding situation. His HR is also higher at the same watts on the 90mm. My guess is he uses more core to stabilize it. My testing is NOT scientific as it is not repeatable and I can't control the variables - just like a real pack race.

Doge

Seen today at the ITT. See prior two pages for the discussion. Somebody else is having fun too.

tetonrider

there's been lots of stuff by people who model actual wind on courses. some of it is pretty surprising.

you can read a whole bunch written by poertner--it's pretty fascinating stuff. in brief, our minds very easily grasp differences in weight (both in terms of feel (lifting the bike) as well as measurements). reduction in drag is less easy for people to grasp (intellectually) and to feel because we get used to the additional speed very quickly...but very easy to see in terms of data.

what pro riders choose is not always the best indicator of what is fastest. that said, CONFIDENCE is huge, and if a rider believes he has the best stuff, he might ride better even if he has put himself at a disadvantage.



pretty much......no. can you name a single road race where bikes were weighed? (for TTs this happens at national championships only and NRC events--but even for NRC events road bikes aren't typically weighed, nor are they weighed at national championships.)

if you know of a situation where this is not the case, i'd love to hear it. (can't speak for junior stuff....maybe they check the kids @ stuff like VOS but i doubt they do anything other than gearing for the RR.)

(for the record, my TT bike is UCI legal in terms of dimensions and weight, but many that i race against choose not to ride a UCI-legal position in the events that don't check.)

using someone else's data is not a substitute for one's own testing, and now you get to some interesting stuff....like energy required to control wheels that might be too deep for a light racer. i can believe a light rider needs to use more core to stabilize a bike in windy conditions with 80mm rims--and that means less energy to put into the pedals.

as always, do your own testing, but ignoring testing performed by some of the most knowledgeable guys in the industry can mean not giving oneself a head-start in that process.

a buddy of mine is an aero advisor to a number of world tour riders; they don't always listen to objective data, and it is interesting to hear his stories. some of them have very deeply head beliefs that were passed down to them by their parents, coaches, etc. it's not surprising--we see this all the time in normal life.

how many people do things like use shoe covers in a TT without having tested them, just as one example?

Doge

I didn't think I suggested I was ignoring any of it. It is good, I believe it, but what I have seen does not deal with riders controlling their bikes from external forces causing a change in momentum. Things like road variations (bumps), air turbulence as well as response to race conditions, such as attacks cause the rider to have to correct - accelerate even if its just from a minor road bump. I want to see that data on the work dealing with corrections and non perfect straight line riding with constant air flow. I have to admit I have not looked much because I think it isn't there. If you have links to such data or even discussion I will read them.

Doge

He didn't write this, but is quoted. Am I reading correctly that as speeds increase from 20mph to 30mph the drag on the wheels barely goes up - even 28 spoke wheels? https://www.zipp.com/_media/pdfs/tech...nary_speed.pdf


Also mentioned is the disruptive sound pressure from solid spoke wheels. I remember David Nayer of Welcome to Nimble some 10 years ago discussing this and how changing the spoke design and fork width would eliminate that. Current TT bikes have a lot of space between forks. We use Nimble Crosswinds still (today) and they are silent at 30mph.

tetonrider

not directly what you're after, but if you look into the design of the first carbon wheels used in P-R you get some insight into the design and testing process.

tetonrider

yes, your interpretation of that chart is correct.

re: the 2nd point....much is made about the disruption in airflow with a bladed wheel & forks. IME there is a bunch of repeated lore in that area. generally wider forks handle that better. also........rotational drag (or lack of) is a thing that is not measured in most (all, i believe) tunnel testing, but it is evident in velodrome and field testing.

even an "authoritative" test (tunnel) can be wrong if the use case is not understood--or if one is focused on an incomplete subset of parameters.

Doge

Zipp chart shows no significant increase in wind resistance force from 20mph to 30mph while Mavic (just a quick Internet search result) says 20kph to 40kph = 4X aero drag. Why weightings should be applied to wheel drag data to measure aerodynamic performance ?Engineers talk

I don't know if its an editing error, or if they actually saw those numbers and thought nothing of it, but for Zipp to have a rather old article on their website indicates few call them on it - or I still have no idea what they are saying.

RChung

The closest thing I've seen are data from Team Pursuit riders. As you probably know, the riders swing off and rotate through so although their speed shouldn't vary a lot, it does vary some -- and their power varies a lot as their drag rises and falls. The yaw range isn't huge but it's not zero. I can't remember seeing anything in this context that was fundamentally different than what we saw for each individual rider. That is, if a rider had low measured drag from individual tests, that rider still had low drag in the team pursuit even though the "racing situation" was much more variable (the actual values were, of course, different but if rider A had lower drag than rider B as an individual, rider A had lower drag than rider B when in the team -- there was no magic cross-over that invalidated the ordering). Team pursuit isn't open road racing but everything I've seen suggests that test results gathered in "controlled" conditions carry over to less controlled conditions.

Doge

I wouldn't expect any. Team pursuit riders are on a near perfect surface, controlled air flow (indoors), are particularly smooth riders and hold their acceleration changes to a minimum. That is also why more than not they use front discs. I don't think the laws about aerodynamics change.

This started where I mad a recommendation to a poster:
Originally Posted by Doge I believe the tests, but think about how you will be racing and those tests may not be as relevant to you. Aero bikes are not the most predominant in the pro peloton.

To which there were responses with articles about how pro riders are slow to change and how the mental matters, which are all true. But what is still true is aero stuff may not be the best choice for how you ride. I/my son are not resistant to change, we test tons, and find the real world way he rides makes some aero equipment not the best for him.

We did a fun thing using TTish wheels and helmet for a crit. Other than NCC and UCI races these wheels can be used - including in NRC races. They worked fine in a TT off the front mode, but my son didn't like them for general in pack riding. He said they were too slow to respond and the bike moved differently. I recall not seeing any pros/cat 1s or Cat 2s riding with these this last year. Would they if they knew they were more aero?

tetonrider

i'm not commenting on the validity (you are reading Triathlete magazine)--just saying that your interpretation of the data on that chart is correct. but you knew that because it is in the text as well.

ask josh poertner about what they saw. i bet he'd reply.

RChung

The laws of aero don't change, but the laws of rolling resistance and wheel inertia don't change either. The aero effects measured in wind tunnels have been validated by field tests outdoors. The rolling resistance and wheel inertia effects measured on smooth rollers have also been validated by field tests outdoors. The drag for individuals, whether in wind tunnels or on velodromes, have been validated by field tests outdoors. Wheel inertia effects tested in velodromes under near-controlled conditions have been validated by field tests outdoors. Aero results for individual and team pursuit and team TT riders have been validated by field tests outdoors at non-zero yaw, both on the flat and on rolling terrain. So all of these results have been shown to be consistent across these tests. What we haven't yet seen is whether results in a peloton vary from what we've seen -- but that's because no one wants to wire up everyone in the peloton with needle-like yaw sticks. However, everything we've seen thus far is consistent with the simple tests (in the sense that ordering is preserved although the actual absolute raw differences will, of course, differ).

Doge

The other conditions don't come into play on the track. You can ride 19mm tires at 160PSI on the track and they will pass all kinds of tests - on the track, while not so much in many road races.
When these other conditions do come into play equipment is changed. Which is why what the pursuit guys are using is not used on the road. I'm assuming you do not recommend road racing with a disc rear and front. Not so obvious is deciding on 90mm profiles, or 50s or 24s tire width etc. for a real crit or RR. When these other variables enter, other things besides aerodynamics become a larger % of the equation - aero still being the biggest.

Do you think there is a better choice for a RR than a light 50mm profile spoke wheel? Or a 7% climb than a lower profile spoke wheel? The Zipp 808 is faster than both, but a rider riding it may not be - depending on the race.

RChung

Of course. But we've also tested road equipment on the velodrome, and those measurements are consistent with road equipment in the wind tunnel and in field tests on real road surfaces. And when we've tested road tires and tubes on smooth rollers, we get the same results as when we test road tires and tubes on the velodrome or on real road surfaces. So wind tunnels, velodromes, smooth rollers, and field tests produce consistent results when the same equipment is used. And when we tested groups of riders on the velodrome or in team TTs on real roads in real wind conditions, we get consistent results.

The big picture is that thus far we haven't seen a situation where the ordering of drag (inertial, rolling, or aero) is different in these different situations. The absolute measurements, of course, differ but not their ordering.

Doge

What do you mean by "not their ordering" and
What did I post on this thread you disagree with?

Doge

He might. I worked for this guy (Inventor for Inventors) early 80s and went on to work for the company he sold (part of Raytion). At the time we were working on bikes without seat stays and later without seat tubes - they went faster and road better. UCI squashed it, but it might be fun to talk as that was one of Zipps first endeavors. Note the address. I used to ride that Boulevard course 4X a week, then ride RT to San Clemente on the weekends.

Doge

You are correct, and they closed the Ethics thread which is where this belongs. This is a huge problem IMO. Junior has a 13# RR setup. He has a completely UCI compliant TT rig while some riding in National's for a berth on USA worlds team may not. Bikes are not weighed, drug tests are not taken. These are minors and I believe they think its goods to look the other way, but have your roll out 1mm over 26ft - and you are DQ'd.

Last year some USA referee AFTER the TT bikes passed told a kid their seat was not flat and had it adjusted it before the TT. The refs who do not enforce things all year get religion at nationals. If a non compliant rider takes my kid's worlds spot do we turn him in? I think not, but I'd like the officials to be on the ball and not make up rules about seat tilt and number pinning. They should have the rules memorized and enforce completely the rules that are published. This thing in the Giro where the TT rider received a wheel from a non teammate and both received a 2 min penalty amongst the uproar of the media was right on. Know the rules and use the rules. Still - we won't be turning a USA rider in.

tetonrider

i'm subject to the rules for at least one race per year, and i see inconsistent enforcement all the time. some years it is "we're just checking the extensions", others it is "we're only checking something else." occasionally 3:1 is enforced for bottles; other times not. the officials who check the day before are not the ones who check 5' before your start. my personal view is that i'd love to see either ALL rules strictly enforced or NONE of them. in fact, i go with the latter for any amateur (my definition is anyone below the world tour level which is the first level where we can guarantee there is a team mechanic paid to worry about this stuff).

just my $0.02.

Doge

Better yet for amateurs trim the rule book and have only things all refs will enforce. Let them decide if something is OK. For pros with money - Kudos to the Giro refs. Its not about sportsmanship - it is a job. I'd still take referee judgment over rules, but judgment means seeing something, acknowledging it as a rule violation and then determining if and how it should be penalized. A pretty tall order to expect this.

I mentioned I was a soccer referee for over a decade. Same problems, different sport. In many areas they worked it out as it is the referee that decides what is OK or not. I prefer that.

shovelhd

The rules are pretty vague as they are. That's by design. They want refs to make decisions. There are few exceptions. Rollout is one of them.

Doge

I'm a big fan of humans deciding what is cheating or not / what should be penalized or not. But when a rule is spelled out - like 6.8 kg, then a ref should not allow a 6.9 kg bike. Likewise a UCI TT requires a seat 5cm back and some degrees off level. A referee should not have the latitude to decide otherwise (fact - they did), and also should not allow deviations from that.

Not a response to you...
Junior did State TT junior championships yesterday. As our team took 1-4 I have a good idea/know the power of some kids. @hack asked if it mattered so much. A less than recovered kid doing less than the best power can win a TT on technique/experience, and equipment. My guess is power was about 3rd or 4th best for his age group, yet he won.

Daniel is the 3rd bike off. Excuse the music - I hate cycling video to music, but I wanted to prove a point - which I did.
.be

RChung

Hmmm. I've known other people who think that when someone tries to inform them of the current state of affairs that they're disagreeing with them.

Doge

I don't understand that post as it relates to my posts. What did I post that you do not agree with? I assume - you agree with everything that I posted. If not, what was it?

tetonrider

RChung *REALLY* knows his stuff.

just taking a step back, you were implying that experiences in testing may not translate to "the real world" (seems like you are defining it as RRs, crits, pack-riding). RChung stepped in and mentioned that all the rules apply and while something like absolute Crr might change from a velodrome to a chip-sealed road, the ordering of tires tested remains the same.

anyway, you may not feel this way, Doge, but your posts sure do read like you are saying that testing has limited applicability to your boy/road racers in general feeling fast. again, this may be unintentional on your part.

shovelhd

I agree with you in general. Clear cut rules are clear cut rules, and what good are rules if they are not enforced. There may be logistical considerations, though, like they don't have a battery of scales to weigh hundreds of bikes, or enough gauges to measure setback in a reasonable amount of time. So why have the rule at all? Maybe it has to do with insurance, or compliance with UCI regulations. There's lots of fishy stuff going on at USAC.