Helmet field testing? CdA impact

[ed72]

You probably ride as many miles in a month as most people do in a year, so what has your experience been in this regard?

This is kind of a special event wheel. I probably only have 2,000 miles on it, the rim surface looks great but it does have some sort of treatment to improve braking and it works. WRT carbon I have found the FLo60 surface to be very durable. I have worn out aluminum rims touring in mountainous, rainy conditions.

The BikeRadar test against the Enve 7.8 wheels was helpful. The Enve wheels are fast in windy conditions and it was breezy on the day of ttest. Unfortunately, they used a big fat 25 mm GP4000 tire on the 2-spoke. The rim is fairly narrow at around 24 mm whereas the Enve is much wider and the 25 mm is appropriate of it but not the M5. Bram told me to only use a 23 mm if I want speed, faster than 25 mm. The fact that it beat a top contender while being relatively disadvantaged tire-wise was a selling point for me because they are Enve fanboys and should clearly have known a 27 mm actual width tire on a 24 mm width rim is unfair. The 2 spoke still won.

There was a Dutch study that tested four wheels IIRC. A regular box rim wheel, A trispoke, a disc wheel, and the 2-spoke. The wheels were in a fixture and spun to a specified RPM. There was a lateral wind of known force applied. I do not recall the yaw but it was significant (90 degrees??). They measured the time it took for the wheel, in the presence of the wind, to stop. The two spoke took like 4 times as long to stop as a disc. The idea was to show the sail effect of the NACA foil spoke.

 

[ed72]

Odd that so many people think they look ugly. I find them rather appealing

I get lots of people telling me my bike is beautiful. Often motorcycle riders. Young kids yell and scream. An older gentlemen in a Turbo S cayenne Porsche stopped and gave me the hugest 2 thumbs up ever as I was leaned in on a turn. Looked like a bent rack in the back of his rig but then again, I was looking in mirror. It was out in the country and I was haulin arsh.

Cyclists are so old fashioned. They think 36 hole aluminum rimmed wheels with 14g straight gage are stronger and more durable than a 28 hole carbon rimmed wheel built with butted spokes. I have never broken a spoke on the Flo wheels. I have had 3 sets of them. I turned my first spoke on the Flo60 the other day. Three spokes turned maybe 1/4 turn. I hit a pothhole so hard at 25 mph that an aluminum rim would have buckled. I point out that planes are made out of carbon. F1 cars are made of carbon, etc. I've had one bike break. It was steel. I have had like six carbon bikes starting in the mid 80's.

So, why would one think a carbon 2 spoke would be inherently unsafe? Airplanes have two carbon wings. If one of those fails...

 

[Osiris]

So, why would one think a carbon 2 spoke would be inherently unsafe?

I think it may in part be due to all those photos people post showing catastrophic structural failure of CF parts. If you see enough broken frames, wheels, and handlebars, you get the impression that CF must be like plastic, which just shatters on impact. I've even heard "old timers" refer to modern CF bicycles as "plastic bikes". There's one rider in my group who still talks wistfully about the 35 lb steel framed bike he rode in 1971, and how "they really knew how to build bikes back then."

 

[ed72]

There's one rider in my group who still talks wistfully about the 35 lb steel framed bike he rode in 1971, and how "they really knew how to build bikes back then."

I have one of those bikes. a pretty rare one built in Italy in 1972. I'll sell it to him.

I know the type. They like to play dressup. Metal bidons on the handlebar although one bottle on the downtube is considered acceptable. Only wool even in Summer. Tubulars. Clipless pedals are banned or shunned. Black leather shoes.

Back in the hairnet "helmet" days, I was the only racer with a plastic helmet. I took crap. And I did a lot of touring, too. In England, Wales, and Scotland. other riders laughed at me for wearing a helmet saying stuff like where is your armour, mr. knight? Or how often do you come off? I raced in a skinsuit on Avocet clinchers and my self built front wheel had DT bladed spokes and was about 50 mm deep.....in the mid 80's. Vitus Carbon 9 or a Cannondale in crits. They called it the Whale. Not popular with the boys riding silks, steel, and campy. In the early 90's I bought a Ferrari red Kestral with 8 speed Dura Ace STI shifting, I actually had riders (fellow cat 3 pukes) on the starting line tell me to get that "thing" away from them.

If one of the two air foils snapped during a ride, what would happen? Would it be like a snapped handlebar or fork crown? I suspect there would be a lot of rim wobble and unintended braking as the rim stuck the pads. In my mind, it would be slightly less exciting than a blowout on a bent but far, far less likely. I've seen tandem bikes sporting 2 spokes. They weigh a lot. The bearing are the smoothest imaginable unlike the crap Zipp puts into their wheels although one can upgrade for what is it, $300 per wheel. I don't know what 2 spoke uses but they rotate as well as the old Campy hubs of yore. I do know that top of the line NTN Japanese bearings are about $15 a cartridge, I had to put 4 into the rear Powertap hub. After around 2000 miles and at least 500 miles in rain, the 2 spoke bearings are still absolutely smooth as silk. It is a heavy wheel. An event that I considered doing listed 2 spokes as banned and then later also banned bents.

You might recall my opinion. Wheels are the least cost effective speed. If you have 808 wheels, just get a cover for the rear one.

 

[Osiris]

I have one of those bikes. a pretty rare one built in Italy in 1972. I'll sell it to him.

I know the type. They like to play dressup. Metal bidons on the handlebar although one bottle on the downtube is considered acceptable. Only wool even in Summer. Tubulars. Clipless pedals are banned or shunned. Black leather shoes.

This guy has quite a collection of modern bikes, but his favorite right now is a French made 1980's bike he's restoring. It looks a lot like my 1970's ten speeds, right down to those dreadful dual shift levers on the downtube and the metal cages on the pedals. There's nothing special about it that I can see, and he's already ruined whatever collector value it might have had by totally repainting it. He claims to have all the period specific riding gear for it, but always shows up at our groups rides wearing modern stuff, which looks totally incongruous.

Back in the hairnet "helmet" days, I was the only racer with a plastic helmet. I took crap. And I did a lot of touring, too. In England, Wales, and Scotland. other riders laughed at me for wearing a helmet saying stuff like where is your armour, mr. knight? Or how often do you come off? I raced in a skinsuit on Avocet clinchers and my self built front wheel had DT bladed spokes and was about 50 mm deep.....in the mid 80's. Vitus Carbon 9 or a Cannondale in crits. They called it the Whale. Not popular with the boys riding silks, steel, and campy. In the early 90's I bought a Ferrari red Kestral with 8 speed Dura Ace STI shifting, I actually had riders (fellow cat 3 pukes) on the starting line tell me to get that "thing" away from them.

When did pro racers start wearing helmets? Thinking back on it, I'm pretty sure I never saw anyone wearing one in the 1970's. I don't think stores even sold them back then.

If one of the two air foils snapped during a ride, what would happen? Would it be like a snapped handlebar or fork crown? I suspect there would be a lot of rim wobble and unintended braking as the rim stuck the pads. In my mind, it would be slightly less exciting than a blowout on a bent but far, far less likely.

Those spokes are massive. The only way I can see anyone breaking a wheel like that would be from a hard collision with a curb or something like that. I've seen a few CF wheel failures in events like Six Gap, but those invariably turn out to be cheap Chinese knock-offs. The busted frames I've seen were the result of crashing into a bridge, in one case, and into one of those concrete barriers they put up when doing road construction, in the second case. One rider managed to break off the ends of his handlebars, leaving only the center section, and snapped the top tube and down tube. The second guy broke his front wheel, fork, and top tube. Both of these guys were racers, so I imagine these were high speed collisions. By contrast, one of my friends hit a deep pothole which launched him over the handlebars and left him in the hospital for a week, but aside from a few scuffs on the handlebars and seat, his CF bike and wheels emerged unscathed.

You might recall my opinion. Wheels are the least cost effective speed. If you have 808 wheels, just get a cover for the rear one.

I have a full disk on the rear already, but I might use the 808 in place of the Flo 30 I have in front. I need to prepare for my 60 mile TT, so if I don't get a lot of instability from crosswinds, the 808 will likely be the wheel I'll be using.

I tested the new Eole track helmet today on my upright. According to the news, the high today was 91F, but due to the high humidity felt like 99F. They weren't kidding. I'm happy to say that despite the high temps, the helmet never felt uncomfortably hot. Visibility is better than the old track helmet I inherited from Phil, and it's at least as aero. Today I hit a top speed of 31.5 mph on a short straight section of the West Orange trail. It's only a tenth of a mile long, and you can't get a running start, so I always like to see how rapidly I can build speed on that little section. I've never before managed to hit 29 mph on an upright wearing my standard road bike helmet, so seeing 31.5 mph flash on my GPS made me think there must have been a tailwind. I went back to look, but there there wasn't a leaf or blade of grass moving. My power readings weren't higher than usual, and I was wearing the same riding gear I usually do, so I don't know what to attribute it to other than the helmet. I may have to do some coast down testing just to be sure.

On my favorite hill climb I also set a new personal record, averaging 561 watts for close to a minute. My goal is 600 watts for one minute, so I'm slowly getting there. Pity riding the upright doesn't seem to improve my power on the bents, because I could get some serious speed on the M1 at even my current one minute power output.

 

[ed72]

When did pro racers start wearing helmets? Thinking back on it, I'm pretty sure I never saw anyone wearing one in the 1970's. I don't think stores even sold them back then.

I think it was more like 2001 that helmets became mandatory and widely used in the professional ranks. I stopped going to watch them in person around 1991, when I changed jobs and also got married. I did not go every year but I tried to at least watch something in person, I loved Paris Roubaix in person.

I had a red helmet like a hockey helmet and also a yellow Skid Lid helmet back in the late 70's, IIRC.

I tested the new Eole track helmet today on my upright. According to the news, the high today was 91F, but due to the high humidity felt like 99F. They weren't kidding.

It was 94F today and 97F yesterday. Tomorrow will be 97-100F with heat index 108-112F. I am doing a 300k brevet in the hills tomorrow after much contemplation, the bad side won. What did Nietzsche say? If it doesn't kill you, it will make you stronger? But then again, he is dead.

Your high temps and high humidity are very fast conditions, so, that plus the helmet probably explain some of the increase. I suspect you are getting more fit, too.

 

[Osiris]

It was 94F today and 97F yesterday. Tomorrow will be 97-100F with heat index 108-112F.

Sounds like your part of the country is even worse off than Florida. A few years ago I was vacationing in upstate NY at exactly this time of year and it was 74F all week long, while Florida was roasting. So glad I brought the bike with me.

Your high temps and high humidity are very fast conditions, so, that plus the helmet probably explain some of the increase. I suspect you are getting more fit, too.

The odd thing is that today I was on my "slow" upright; the Specialized Roubaix. I didn't expect it to be as fast as the much more aero Specialized Venge, much less faster. It is shod with a fast rolling set of Vitorio Rubino's though. Maybe the Gatorskins on the Venge slowed it down.

 

[ed72]

I picked the old faithful helmet yesterday, the one with the big honking mirror and lots of vents. I walked four climbs in the 15% range. Rested at the 9 controls on the 300K, more than 11,000 feet of climbing per Garmin but it felt like more. 12:33 moving, 13:55 total time. I figured the amount of energy and overheating trying to muscle up extended pitches and real climbs of 15 degrees wouldn't be smart. It hit 101F supposedly.

 

[Osiris]

I picked the old faithful helmet yesterday, the one with the big honking mirror and lots of vents. I walked four climbs in the 15% range. Rested at the 9 controls on the 300K, more than 11,000 feet of climbing per Garmin but it felt like more. 12:33 moving, 13:55 total time. I figured the amount of energy and overheating trying to muscle up extended pitches and real climbs of 15 degrees wouldn't be smart. It hit 101F supposedly.

Yesterday my group did a metric century, all on open roads. Reportedly several riders couldn't finish due to the heat. To be fair, none of these guys were in particularly good shape, and shouldn't have been on that ride in the first place.

I did my own 33 mile ride, testing my new Eolus helmet. Despite the absence of vents, there was a surprising amount of air movement inside it once I got going. It really wasn't that hot unless I had to stop for any reason; then it felt like the inside of an oven. It should be fine in cooler weather though. I was relieved to discover that despite having more of an egg shape than the old helmet, I can still wear it on the M1 without the back of the helmet coming in contact with the rear tire. There's only about 1/2 inch of space between them with my head tilted all the way back, but that's all I need. Visibility is much improved over the old one. The longer visor not only creates much smoother airflow over my face, but now the lip of the visor is no longer interfering with my view of the road. This may just turn out to be the ideal helmet for all of my bents.

 

[ed72]

testing my new Eolus helmet. Despite the absence of vents, there was a surprising amount of air movement inside it once I got going. It really wasn't that hot unless I had to stop for any reason

It does look fast.

I tried to find reviews on it and came up dry. It was introduced about 5 years ago. Bad marketing?

 

[Osiris]

It does look fast.

I tried to find reviews on it and came up dry. It was introduced about 5 years ago. Bad marketing?

Bad marketing indeed. I wasn't even aware of it's existence until I it showed up randomly in one of my searches. At a sale price of $279.00, I just couldn't see how the $500 Casco helmet could be that much better, assuming I could even get one.

Given that the old Eolus proved to be nearly as aero as a full blown TT helmet, I'd be willing to bet that you'd need a microscope to find any advantage my LG Vortice has over the new Eolus.

I'll probably do a power/speed comparison next weekend between the Specialized Evade and the Eolus. I'm interested to see how much an advantage the Eolus might offer at sustainable speeds on my upright. I hate this sort of test because I find it very difficult to hold exactly the same speed or power output for long periods, but I'm thinking two back to back tests, going both directions on a 4 mile Strava segment should give me a pretty good idea. I may do more if it doesn't get too hot out there.

 

[ed72]

I hate this sort of test because I find it very difficult to hold exactly the same speed or power output for long periods,

I agree on an upright. I am confident to hold a position on a bent. On my 12 mile long river road section, there are many strava segments and it is unusual for my power/speed nexus to vary by more than a watt or two in calm conditions, adjusting for 0.08% elevation difference in direction.

 

[Osiris]

I agree on an upright. I am confident to hold a position on a bent. On my 12 mile long river road section, there are many strava segments and it is unusual for my power/speed nexus to vary by more than a watt or two in calm conditions...

I can't manage that level of consistency even on a trainer. It's not the fault of either the Garmin Edge head units or the power meters, because I've had the same result with all of them. I would much prefer doing coast down tests, but I haven't been able to find any slope that would allow me to approximate my rolling speed on an upright. They're either too steep or not steep enough.

The thing I keep wondering about is, if track helmets like the Eolus are so much more aerodynamically efficient that just swapping your road helmet for one will add ~2 mph to your top speed, why isn't everyone wearing one? The lack of ventilation seems to be the most plausible objection, but having used one for the past two weeks in hot July weather, I can't see that being a deciding factor; the Eolus isn't that much hotter than any of my road helmets. In cooler weather it wouldn't be a factor at all.

Of course it could be said that the +2 mph advantage occurs at speeds that few riders could match even in a sprint, so let's say that it's only +1 mph at the kinds of speeds a fit rider can maintain. A +1 mph advantage is still huge.

Maybe it just boils down the the fact that track helmets look kind of dorky, like something out of a low budget science fiction film.

 

[ed72]

Of course it could be said that the +2 mph advantage occurs at speeds that few riders could match even in a sprint, so let's say that it's only +1 mph at the kinds of speeds a fit rider can maintain. A +1 mph advantage is still huge.

I do not doubt the order of your helmet testing. I usually like to do ABBA testing just in case the wind changed slightly. To be clear, I am sure your Spesh helmet is slower. How much? Not sure. When I do testing on the road, I feel like several days are needed to make a clear determination if I want to know how much something is improving my speed but some effects are so great, it isn't worth the time to quantify. For instance, riding in loose wool LS and tights, it might take me 140 watts to ride 20 mph and only 110 watts in fast kit. So, why bother with more precision.

 

[Osiris]

I do not doubt the order of your helmet testing. I usually like to do ABBA testing just in case the wind changed slightly. To be clear, I am sure your Spesh helmet is slower. How much? Not sure. When I do testing on the road, I feel like several days are needed to make a clear determination if I want to know how much something is improving my speed but some effects are so great, it isn't worth the time to quantify. For instance, riding in loose wool LS and tights, it might take me 140 watts to ride 20 mph and only 110 watts in fast kit. So, why bother with more precision.

I agree with this in principle, though being a "show me the numbers guy," I find it deeply unsettling not to have precise data. Ideally I'd like to have a chart showing what each component (tires, handlebars, wheels, helmets, clothing, etc.) contributes to speed in 1 mph increments from say, 18 mph to 35 mph. I'll bet Dave Brillhart already has something like that.

 

[ed72]

I agree with this in principle, though being a "show me the numbers guy," I find it deeply unsettling not to have precise data. Ideally I'd like to have a chart showing what each component (tires, handlebars, wheels, helmets, clothing, etc.) contributes to speed in 1 mph increments from say, 18 mph to 35 mph. I'll bet Dave Brillhart already has something like that.

My data is precise, it just isn't accurate. This is why I can accept anyone who wishes to criticize any absolute values I throw out. This is also why my approach is to test the same day under the same conditions and not to compare to other days. I control what I can control or compensate. Dave is a very bright fellow; however, I am not so sure he spends much time on aerodynamics or I have never seen him write about it.

For example, I test on two different roads. I sweated getting the Crr for GP4000 tires correct on both surfaces. Now that I ride GP5000, I just keep the speeds the same and that way I have a high confidence when I compare two different pieces of gear aerodynamically. It takes a lot of time to measure Crr on real roads and then temperature has to be compensated when you are looking for small aero gains. A PITA. I just keep the same wheels and tires and the same speed to be able to ignore any variation in tire Crr. If I use Crr of 0.004 instead of 0.0045, I get a slightly inaccurate final CdA but the variation or precision of the CdA figure is minimally impacted. I know my tires run in that range, closer to the lower level on the good roads and maybe a little higher (0.0046??) on the not so good road. A much bigger mistake is not getting the humidity, temperature, and atmospheric pressures.

In the end, if changing position or a helmet or clothing lowers CdA from another position, helmet, or clothing, it will show up in performance (KoMs?, TT, etc) and that is what really matters not the imputed absolute CdA. All the individual pieces work together, they are not really independent. Quite frequently I measure mine at under 0.150 but other times closer to 0.170 but on any given day, it will be consistent. I know clothing has a big impact for me. I also "think" how I close my tailbox matters a lot. I crashed it and unless it is taped shut, it catches a lot of air. The problem I was chasing before was a lose aerojacket cover on the rear wheel, unbeknownest to me it would open and close flapping in the wind. Once it failed outright, my CdA went back into my normal ballpark. I had been thinking a brake was dragging or it was this or that. What has surprised me is the seemingly minor things that cause huge variations.

I have come to the conclusion that a wind tunnel trip is only worthwhile once all the low hangin fruit has been picked but that level of testing is pretty easy albeit time consuming.

 

[Osiris]

Since you've done quite a bit of tire testing, when it comes to outright speed on smooth pavement, what would you say is the best air pressure for a set of 25mm GP4000's with a 165 lb rider? I imagine the type of inner tube might factor into this, but I don't know how much it matters. I've asked people's opinions on tire pressure for years, but the answers I've gotten vary quite a bit and don't seem to have any empirical basis.

Also, if you were training for a 30 mile TT, how would you go about it? I watched a presentation by one of Britain's top TT racers who insisted that it's essential to actually ride the distances you plan to race, and that interval training isn't enough.

 

[ed72]

Since you've done quite a bit of tire testing, when it comes to outright speed on smooth pavement, what would you say is the best air pressure for a set of 25mm GP4000's with a 165 lb rider? I imagine the type of inner tube might factor into this, but I don't know how much it matters. I've asked people's opinions on tire pressure for years, but the answers I've gotten vary quite a bit and don't seem to have any empirical basis.

This series of blog posts is the most thorough and balanced view of tires and tire pressure that I have read.

In my opinion, latex tubes are always faster than butyl. It is better to err on the side of under inflation than over inflation. The uprights typically use less pressure in the front tire to obtain Frank Berto's 15% drop. On my bent, the front to rear balance is about 50/50. I run 95psi in 25 mm. This works best on my roads. On smooth surfaces like a track or really good pavement, I might go higher. On the Van Fleet trail, the pavement overall is pretty good. I might go 100-105 but no higher. On normal paved bumpy roads, the best pressure for you is probably in the 85-95 psi range as the fastest overall. Caution.....the gages on pumps are often very inaccurate. Mine is wrong by 12 psi.

https://blog.silca.cc/part-4a-rolling-resistance-the-history-and-previous-works

https://blog.silca.cc/tire-size-pre...resistance-and-more.-part-1-how-we-got-to-now

 

[ed72]

Also, if you were training for a 30 mile TT, how would you go about it? I watched a presentation by one of Britain's top TT racers who insisted that it's essential to actually ride the distances you plan to race, and that interval training isn't enough.

Those guys know a lot over there. Take what I write with a huge grain of salt. But, it is also important to understand that individual response to training regimes vary.

I would personally use longer and longer intervals over a period of months that cover the time of the race (about an hour). You have to get your brain used to the discomfort. Specificity, specificity, specificity. The ability to burn lactate is part of what you are training.

You could start with shorter intervals, say 6x5 minutes. Then 5 x 8 minutes. 4 x 10 minutes eventually working up to 3 x 20. The intensity of efforts obviously declines as the time interval increases. I seem to recall Andrew Coggan doing something similar recently and claimed it got him in the best shape of his life. Not sure it if was UKTT forum or Slowtwitch (before they banned him). The reason I think this might work for you (building up the time duration hard efforts)? An hour at threshold is hard physically and mentally.

 

[ed72]

WRT 30 mile TT.....most important to train on the bike you intend to use (obvious, I think)