twocicle

Very interesting numbers. But I doubt you could find any decernible racer who would honestly report that a set of 4lb heavier wheels felt as lively and accelerated as quickly with equal perceived effort as would a set of lightweight racer/climbing wheels. My experience in crits and track, flitting through corners and accelerating repeatedly at max effort says otherwise.

Just my opinion and bias I guess.

waynesulak

I am always only minutes from thinking about how to make the bike go faster or something like that. Like mentioned in the Gates Belt thread some of us have to keep changing things.

waynesulak

Part of the effect of heavier/lighter wheels is how they work as gyroscopes when spinning fast. With a lot of rotating weight they should be more resistant to turn and that should make the bike feel more stable or sluggish in a turn.

TandemGeek

Absolutely not; you can clearly feel the difference even without being a racer.

But, we're not talking about folks who are out racing crits here... are we?

That's the underlying message here: just understand what it is you're looking for in terms of your needs, wants, desires and expectations.

Spinergy's are not aero anymore than Topolino's, but neither is my body, clothing or riding position and I'm hardly the exception in our esteemed collection of recreational/sport riders.

I can get a bigger aero bump by wearing a tighter fitting jersey and hitting my drops than I'll ever see out of a set of 80mm deep HEDs, but that's not how I do most of my riding these days.

I do, however, enjoy the very fast acceleration you get with lightweight wheels when starting hard from a dead stop, sprinting out of a corner or jumping up out of the saddle to attack a short, steep climb. But, other than those very brief moments that make up less than a few hundred yards during a 25-30 mile ride, I'd be hard pressed to tell the difference between my 1,500 gram Topolino's or my 1,980 gram Deep-V/White Ind wheelset, but the comfort is there all the time with the Topolino's, especially when the pavement's not the best. The Spinergy are in the same realm as the Topolino's when it comes to weight/performance/comfort.

So, at the end of the day Aero's interesting if you can make use of it and is certainly a bigger pay-off if you're trying to go fast at a constant speed over long distance where you don't have the luxury of drafting and can hold a fairly aero riding position otherwise the benefit is lost in the noise level. Light weight is great for frequent, rapid acceleration and climbing which is, after all, nothing but a long series of accelerations for a lot of team that don't climb smoothly, but comfort is all the time and can pay off huge divendends if you spend a lot of time in the saddle.

IMHO, neither the aero or weight benefit of racing wheels will really do long-term good if you use them as your every day wheels. They'll just make it little easier to ride using the same effort you'd use with less slippery or svelt wheels unless you're measuring your power output, heart rate or some other biometric measure as a means of making sure you're working harder and not just piling up mileage. Note: We tend to pile up mileage these days.

So, a the end of the day being fresher and less fatigued may well yield a 1 mph increase in average speed, more so than anything else over the course of a 62 mile hilly... and that's what our friend Jack has described, as did another recent contributor.

I know that I feel a lot fresher after riding 100 miles on my Harley FXDWG than I do after 100 miles on my BMW R1100S... and the same is true of our Calfee vs. the Erickson.

WheelsNT

Interesting... I wonder what his cadence was for the climbing portion? It seems like the rotational speed variation of the wheels during each pedal stroke would be greater, maybe much greater, for slow-cadence standing climbs. If he was seated and spinning along merrily at 90 rpm, there wouldn't be much acceleration per stroke.

Also, I only see one set of graphs for each ride, so I guess he used the data as a base and then calculated the effects using his model. There have to be some assumptions involved in that process. The first assumption that occurs to me is that his body performs equally when the equipment is changed.

I also wonder what the resolution is on the acceleration data.

TandemGeek

I'm sure Jan H. and Mark VdK could demonstrate how a 650B rando bike with 45mm tires with 80lbs of air would out perform all of the given scenarios... God love 'em! Bicycle Quarterly remains one of my favorite reads.

It, like so many things I've read with interest, provide insights, opinions, data and even a few facts now and again that help you to challenge your own assumptions, correlate your experiences and draw your own conclusions as they pertain to your cycling interests and needs.

It's good to read and question what you read...

waynesulak

Interesting you should mention wide tires. I use them and love them but like aero effects I don't expect to go much faster with them. Your point about freshness at the end of a long ride is well made and applies to nice soft wide low pressure tires. I doubt the ride of any wheel can absorb more road harshness than a good 38-42mm tire at 70-80 psi on a tandem or 50 psi on a single. With those pressures the chip seal buzz never gets to the rim because it is absorbed in the tire. The tradeoff and there is almost always a tradeoff is that they feel slower (even though they are not slower) than a good high pressure racing tire. Feeling slower is less fun for most people and that is why my wife likes her Miata. It feels like you are going 80 when you are going 50. Lots of fun but not more speed than a nice fast luxury sedan.

Want a nice fun little drive take out Miata
If we want to drive a few hundred miles and feel good take another car.

twocicle

Some things just fly in the face of what we "know" as fact...

Fabian Cancellara racing a heavy 16.5lb bike (which will make him deathly slow), with titanium pedal spindles (which he will snap like twigs), all the while using cable actuated shifting instead of electronic (so he will inevitably mis-shift and fall over on the cobble climbs), and riding 50mm carbon rims on cobbles (which we all know is just asking for trouble). Net result... winning Flanders.

Moral of this insanity... everything is just icing on the cake. Lightweight wheels may help you be 1mph quicker, but you are still the motor.

Ritterview

As for the aero vs. rotating weight argument, theories are one thing and practice is another. If aero trumped everything, and rotating weight was negligible, then I'd expect that professional cyclists would use the same 60-80 mm rims on road races as they do on time trials. But, it seems that they favor rims of 45-60 mm on road races.


Road race, generally <60 mm


Time trial, >60 mm

True, on a road race the racers are often in the peleton, and thus are in a draft, which reduces the advantages of aero. However, since they end up having to add weight to their bike anyway to make the UCI 6.8 kg limit, if rotating mass was a negligible hindrance they'd just as soon add it to their rims, and gain some free aero advantage. But they don't. It must be, therefore, that the inertia of rim weight is not negligible.

TandemGeek

True...

But then again, we're not professional cyclists who have eeked-out just about every ounce of fat on their bodies and achieved a level of performance where tenths and hundreths of a second count and those .15% - 1.9% values have far more impact than they do on "fluffy" weekend warriors enjoying a spirited club ride, a nice metric or perhaps a 200k rando... which has been the context of the most recent chapter in this thread.

Then again, I haven't investigated why pro riders choose the wheels they do for certain stages of late -- and in particular UCI rules that most likely prohibit the use of certain equipment outside of a time trial -- and Lord knows there are a whole lot of different things to consider when trading off things like wheel strength, stabilty & confort against weight, drag and of course sponsorship agreements regarding what equipment will be used by a given team and/or athlete.

twocicle

Are pantyhose more or less aero than shaved legs?

Dang it... missed posting that topic by one day.

budhaslug

Don't tall rims catch crosswinds quite a bit more making them too much of a danger in a peloton? I think that alone explains the variety of rim heights in different types of stages. If crosswinds didn't exist, I would be surprised if most pro's didn't pick more aero wheels on everything but the biggest climbs.

But I'm definitely with TG that almost everything Pro's do and choose is largely irrelevant to most non-racing riders like myself.

Dean V

Accurately maneuvering and controlling a bike in a close packed group on even moderately windy days could also have something to do with it.
There is also no doubt that a lower inertia wheel feels significantly more lively but I think if you put the stop watch on it the maths will prove to be correct.

DubT

Stop watch, data, etc., I will always go light and as aero as possible. I do not care what the figures say, in my mind light and aero is faster so I go light and aero.

if I was the op, I would try to borrow a set of light wheels and see how that impacted their performance.

When we raced the tandem TT nationals back in the early 90's we used aero bars up front, a full discs in the rear and a 50mm deep front rim. We also wore skinsuits and aero helmets. We finished 3rd in our age group.

When my daughter decided to start racing, I told her if she wanted to go fast she had to go fast. If you want to average 16mph then you need to be able to ride 18mph for several minutes. Intervals are the way to get faster. However a light bike is still more fun to ride. We went from a 40 pound bike to a 27 pound bike and it is much more fun to ride. We have each lost weight which also helps.


Wayne

Ritterview

• The theory in the article in the link you provided was specific for neither professional racers nor tandem teams. Aero and gravity are universal, and their principles apply to all.
• The benefit of seeing what road racers do is that they are expertly coached, they are in a competitive environment, they are numerous, public, and have skin in the game. It is like looking at the stock price or the point spread or market based indices, rather than an academic treatise on a subject.
• Though full wheel covers are restricted to time trials, there is no restriction on 80 mm rim depth, as these are occasionally seen on road races.
• Though sponsorship matters, it makes no sense for a wheel sponsor to dictate disadvantageous rim depth.
• The other items you mention as affecting rim choice would be a source of variability among riders in a discipline, but would not explain the differences in rim depth between disciplines. For time trials, every change that is seen from road racing is due to aero unless proven otherwise.

waynesulak

I agree with the similarity but would use that example to point out the fact they are fallible. It is very common for companies to be bought out simply because the market greatly undervalues the company and another company can sell of the assets for a tidy profit. A lot of expertise making decisions but that does not always make the right outcome.

Aero helmets are an example. Much money and top expert time was spent in wind tunnels designing the aero helmets worn by Lance.




Now they are old school and the new style is used by Wiggins:





Giro and Lance had a lot of skin in the game and a lot of expertise yet now we see another result. It is easy to say these are advances and to be expected. I agree but it points out that the experts are learning as they go and do not have the final answers to their own challenges much less the challenges facing an middle aged couple on a tandem.

The pro usage is a good data point and the closer a team is to there situation riding their bike the more that data point can help. I think 15 mph is not very close aero wise. I have read articles that say that aero wheel benefit is not large enough to measure until speed reaches 30 kph. Maybe that is not exactly right but it is well over 15 mph.

Dean V

The deeper aero rims (look at the data, Hed etc) only get much of an advantage over the shallower wheels at higher yaw angles. Then they can generate more lift (less drag) due to their larger area. Higher yaw is due to more wind, specifically cross wind, which is exactly the time when you don't want to be struggling to hold your line in a peleton. So in other words, in light wind they won't help, in stronger winds they effect bike handling too much.

TandemGeek

[*]The theory in the article in the link you provided was.... intended to make readers "think" about wheel selection; it was relatively simplistic and instructive. If you'd like something more analytical, here's another excellent read replete with equations from our good friend David "Pardo" Keppel's web archives: https://pardo.net/bike/pic/fail-027/index.html

[*]The benefit of seeing what road racers do... is that through the power of marketing they help the bicycle industry and pro cycling sponsors achieve their business goals.

[*]Though full wheel covers are restricted to time trials, there is no restriction on 80 mm rim depth... Actually, that's not true. Bicycle wheels for use in UCI events must either meet a very conservative "standard" or undergo a fairly expensive testing protocol and be approved as "non-standard" wheels by the UCI for use in mass-start events. The list of approved "non-standard wheels" is huge, and so is the revenue it generates for the testing program and the wheel manufacturers who get those wheels approved. Interestingly enough, UCI rules mandate those huge graphics so that the wheels can be readily identified by officials.

[*]Though sponsorship matters, it makes no sense for a wheel sponsor to dictate disadvantageous rim depth... unless the disadvantage of the associated weight or depth of the rim is insignificant, i.e., road races on calm days without much climbing.

[*]The other items you mention as affecting rim choice would be a source of variability among riders in a discipline, but would not explain the differences in rim depth between disciplines. Weight on wheels is weight, and aero is aero and without dope it's hard to know what might give a rider a "boost" on a given day where the pros and cons of deep + a little extra weight vs. not-so-deep a little less weight net out and it's the placebo effect or just a good night's rest or the promise of a reward that makes one rider faster than another.

From Pardo's Rotating Weight analysis...

Quote:

A lighter wheel often gives a "snappier" steering feel. Even if that has no mechanical advantage, it still can help the rider go faster: If a bicycle "feels" snappier, the rider will go faster.

A U.S. Olympic coach famously told the team they had a "secret weapon", which was helium in the tires instead of air. "Helium is lighter". If you do the PV=nRT calculation you find the weight advantage is smaller than plucking out a few eyebrow hairs, but the riders, convinced they had a signficant advantage, rode faster.

Summary

Reducing weight is useful, whether removed from the wheels or frame.

One important question is whether a gram from the wheels is like two grams removed the frame. The answer is "no", it is at most like 1.5 grams removed from the frame. But for things like climbing and hopping, a gram removed from the wheels is no different than a gram removed from the frame.

A second question is whether reduced rotating mass effects are significant. Again, the short answer is "no". The big energy savings of lighter tires, fewer spokes, and so on is lower rolling and aerodynamic drag, not inertia. Further, reduced drag helps always, reduced mass anywhere on the bicycle helps during climbing and accelleration, but reduced rotating mass helps only during accelleration.

This analysis is useful in that it can help riders make smarter buying decisions. If the same price saves either 1g of rotating mass or 2g of non-rotating ("frame") mass, the 2g frame mass avings is almost always the better deal. Indeed, in most cases, whatever is the cheapest way to save a gram gets the most benefit for a given price: by going with the best value, a fixed spending removes the most grams and thus gets the biggest advantage.

This analysis is also useful in that it shows improving aerodynamics without losing mass can also be a good deal. Such changes are not quantified here, but it shows the effect of improved aerodynamics is often quite large, and thus can be a good value for the money.

DubT

Dean, we live in Illinois on the prairie and there is almost always a wind blowing. That is why I like the HED 3 wheels, at times it feels like we are getting a boost from the wind on the wheel. Since we ride alone 99 percent of the time then there is not an issue with riding in a peloton.

Ritterview

Of potential tandem interest, Zipp has announced they are making new disc wheels. The advent of road and cyclocross disc wheels is going to make for a lot more off-the-shelf tandem wheel possibilities in 135 OLD.

Zipp 303 disc wheels point to hydraulic Red group


The new Zipp 303 Firecrest disc-brake wheels will come in tubular and clincher


The new Zipp 303 Firecrest disc-brake wheels will be available in July

PMK

Consider also, the lighter wheel may feel better to accelerate or decelerate, but if it is flex prone in side loads, the gains are lost or at a minimum, moot.

This has happened with 29 wheels off road. I have ridden some light wheels that were all the rage, very nice until cornered hard or even worse, riding across root or rock sections where the wheels flex and won't hold a line. Good thing they are light and easier to get back up to speed since time was lost in corners or holding a line.

PK

diabloridr

A couple of nit-picks:

1) Wheel covers are not permitted in UCI events - however actual disk wheels are for non-mass start events.

2) Wheels over 25mm in rim height, less than 16 spokes, or spokes greater than 2.5mm in thickness require testing to something the UCI calls a "rupture test" to permit use in mass-start events. That said, the list of wheels which have passed this test is lengthy.

waynesulak

Firecrest road rims are famous for their width exceeding the tire width and the aero advantage that brings. Seeing the tires marked 33 makes me ask, what is the rim width of the those Firecrest rims?

merlinextraligh

^ The tire is a Dugast cyclocross tubular, which is a popular ultra high end cyclocross tire. The 33 almost certainly refers to 33mm, which is the widest tire allowed in Cyclocross, where UCI rules are in effect.


The 303 firecrest tubulars have a maximum width of 28.5mm, which is wider than the 404 firecrests, and wide enough not to work in some road frames.

merlinextraligh

As for deep sectioned rims in road races, Tyler Hamilton won the US Pro Championship using 808's on a course that included multiple trips up Paris Mountain.

Even at the amateur level you'll see people using 80mm or deeper rims in crits and road races, occassionally.

IMHO, the reason you don't see more really deep rims in mass start races is more handling,particularly in cross winds, and to a lesser degree ride quality, than a weight consideration.