I rode Raleigh 70.3 last week avg 24.8 mph.

So for higher yaws and lower speeds: gp4000's?

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In general...

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http://bikeblather.blogspot.com/

That combo (same as mine) begs for a SS23 front/ Force or SS23 rear. That has been my strategy and has worked well. I am trying a GPTT 25 on the rear though for a 70.3 next month.

will a gp force be faster on a fc 808 than a gp4000s?

Yeah I'm thinking about switching to SS's. I may just need someone to push me over the edge to pull the trigger.

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I have been running Force rear and Gran Prix TT front with Challenge latex tubes for years looks like I don't need to change thing:)

Yes

I think I'll put a GP SS 23 on my Jet 9 plus and run the GP TT 23 out back on my Enve Classic rim with disc cover. Been running a Force up front and the Specialized Turbo Cotton out back.

I have been running SS for as long as I can remember with Challenge latex tubes and have never been happier. ZERO flats during a race and I ride them in training as well with ZERO flats.

Sorry to hear you are injured. I hope your recovery goes well.

i felt the same way, Gerlach's words gave me that little push over the edge, been running them in all races on my front wheel for all races in 2016. Zero issues, run them with latex and sealant. I have been running a TC rear but after reading this going to switch the TC out for a force i have laying around. Also have a GP TT 25mm on order.

Take the leap to the dark side of the SS! FYI when you first feel it feels sooooo thin don't be scarred.

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2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

Josh,

So I took some measurements from different tire/wheel combo's I'm running and curious how to interpret the information - or is it just "fun facts"?

Combo 1 (Rear): Max rim width - 30.2, brake track - 25.2, bead - 17, tire width - 26.5
Combo 2 (Front): Max rim width - 30.2, brake track - 25.2, bead - 17, tire width - 24.5
Combo 3 (Rear): Max rim width - 27.5, brake track - 26.5, bead - 17.25, tire width - 25

Assume I'm around 81-82 kg on race day - 160lbs + 18lbs bike/gear.

Two questions - are these width ratios "good" in your opinion (rim greater than 105% of tire) and what pressure would you run? I've been running 95 psi on all these combos.

Thanks!

Hi Tom,

I'm wondering if your injury is gone now (which I hope for you) and you'd be able to test a Force again ?
I need to decide between GP TT and GP Force on Flo 60 CC for my next IM ;-) . I've seeen GP TT testing faster in RR many times so on a low wind day I'd probably go TT (from Swiss Side testing and Flo Testing of now awesome aero tire... we still see under 7.5° tires are close enough for RR to be the most important factor), but just in case it gets very windy it can be smart to have a pair of Force in the car ;-) ... so I'm curious to see if it was the one you tested at 0.0029 that was a very lucky tire or of it was the 0.0034 one that really came from a bad batch !

Thanks,
Pyf

Majoring in minors here. Their are always two things that a wind tunnel cannot measure and they are the most relevant of the entire study--"Relative Wind" (RW) and road surface caused rolling friction. RW is the wind that the bicycle creates going through the air medium combined with the direction of the wind and speed and the direction of the bicycle and speed. RW varies with speed and the regular wind, it varies constantly in both speed and direction and nothing can be done about it. Years ago, the creator of ADA wheels (Cees Beers), instrumented VDB (TDF competitor and World Champion) with sensors all over him and the bicycle to assess the aero of his wheels. Problem was, VDB was unable to maintain a straight line for any length of time due to varying wind conditions. Nevertheless, the results were taken to the Dutch Aerospace Super Computer and input. The computer stalled and had to be cleared--it could not crunch the numbers. My brother is an engineer at Boeing, so I asked him to ask the wind tunnel guys about the various bicycle and wheel aero tests and when he did, they fell out of their chairs laughing, because ALL bicycle wind tunnel tests are bogus. The reason for this is that wind tunnels were created to learn how to make a shape do something with the air it is going through, because they want the wind to do something--like fly the aircraft. However, an aircraft is a relatively stable thing in the air medium, a bicycle isn't. The wheel is constantly vibrating from road impact and the bicycle is constantly moving around, and that interrupts the laminar flow around it and the wheels and the tires and that creates a very high CRR, which instantly invalidates the test--the vibration disturbs all laminar flow. There is no way around it. The cyclist should choose their tires for how they feel to them. If they feel draggy, try other tires, because they probably are draggy, size of the tires should be chosen to match the road surface for the lowest rolling friction. We do know that wheel rims should have a slight taper to the inside of the rim to smooth air flow around them. We also know that a smaller tire cuts air better at high speed, but it can also increase rolling friction due to road conditions. You have to decide what works for the conditions. Also, extensive testing has shown that thin round spokes are better than any aero spoke made (thus destroying the myth of so-called aero spokes). The fewer the spokes the better, because they can really rip up the air, aero or not, and again, the RW always changes, making so-called aero spokes, not so aero. If conditions permit, the use of disc rear wheels makes sense, even though they have a lousy CRR. The reason for this is that the disc fills up the area behind the seat tube which has an even higher CR than the disc. However, a disc wheel, and for that matter, a deep dish front/rear rim have other problems. Any time the RW is from the side there is a force vector from the wind that forces the rider to lean into the wind to correct his course. The larger the cross section of the wheel, then the more lean is induced and the higher the CRR of the wheel/tire combination. This flies against what most people are worried about on this thread, but it has been proven over and over again. So, why do national and international competitors ride what they ride? Simple, they are paid big money to ride the stuff they ride...You, dear reader, aren't. So, ride what works. Personally, have found that Continental tires (both sewup and wired) have a lively, relatively low friction ride, but they are also harsh which are two conflicting attributes. However, when they are cut, the cut tends to spread, because the tire itself is allowed to expand (it's the thread belts that allow this) with air pressure, so the rubber is under tension. The cut can enlarge, thus endangering the tire, and can't be repaired. If you compete, sew-ups are the way to go. Every TdF ever won has been won on sewups. I like wired on, ride them a lot in training--go thru many sets per year. But when I race, it is always on sewups--currently--DuGast silks, or very ancient Veloflex (Egyption Cotton) or Clement Campaniato del Mundo Setas (almost 30 years old). And believe me, none of those sew ups can come close to the Continental Force tire, except that in the real world, their is virtually zero road friction as I fly past guys shod with Continental Force tires. It has little to do with training or leg strength, because I'm 68 yrs old and has everything to do with what works in the real world. My personal recommendations are to use Veloflex or DuGast silk sewups on the lightest Mavic wheels you can afford. Mavic wheels have a superb bearing adjustment and bearings. Go for a very small rim cross section with as few spokes as possible (depending upon rider weight, of course). If wind conditions allow it (Hawaii, Kona never allows disc or deep dish wheels, due to wind conditions) use a disc rear wheel and slight dish front, but be sensitive to wind--any wind from the side, forget the dished wheels. As an aside, Heather Fuhr won the Kona Ironman and the World Championship on ordinary sew up wheels that I trued and balanced, and with ceramic ball bearings that I designed and installed (synthetic clock oil was the lubricant).

I love this guy... Helping me get to Kona since 2008 and now helping me earn a living... Free chicken.

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So what wheel set would you recommend if one could only afford one set for racing?
Cheers

The injury (a fractured pelvis) is mostly healed. Bone is good, now I just need to work through some muscular issues. I've actually been cleared to ride outside now, and since the weather has been awesome, I've really had low motivation to get on the rollers ;-)

I'm hoping to get to test that tire, along with a few others soon....i.e. in the next few weeks.

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http://bikeblather.blogspot.com/

This a lot to unpack. First, I do not know exactly why you replied to my joke about gatorskins. Second, while an airplane is stable in the macro sense, I have seen a bunch of data from accelerometers mounted on various parts of aircraft and it is definitely vibrating. Let alone on landing where you are working the wing hard, there are lots of dynamics. Third, how does the movement create high CRR invalidate the test? Wouldn't it at the very least impact all of the tires equally, so the results would still be meaningful? It would not impact the fastest tires more, making the CRR equal for them all.

How many times have you been in a wind tunnel? How much testing have you done in a wind tunnel? I have done testing in wind tunnels and that testing was all aerospace related. I can assure you that some Boeing engineers believe that some of the wind tunnel tests are meaningful.

If you want to use clinchers, go with a 22-23 mm Veloflex tire on the lightest Mavic wheels you can afford, preferably weighing around 1200-1400 grams (lighter is always best). If you like Continental tires, well...sure, use 'em, have ridden them a lot, not the Force tires, but the 4000 series and they are OK, just think Veloflex is a bit better. I think Mavic is still using Velomax Aerohead rims--love those things. The Aeroheads have a slight aero shape to them that actually works under most conditions, is light and strong enough to spoke up with 28 or less spokes. The Mavic hubs are the best, and feature a bearing adjustment that can be done while installed in the forks.

I built a wind tunnel to test scale models of spokes. My partner has a PHD in physics and was rated #3 in the nation at the time. Sure, aircraft vibrate all over the place, but they do not disturb laminar flow, bicycles do disturb laminar flow.

Ok thanks, so this will be faster than any deep dish wheels? I feel like I've been screwed by advertising, stolen from.

Ok, so windtunnels do not produce relevant results for bike wheels because of the flows wheels see. But you windtunnel testing is meaningful for spokes. Also, why did you need to test scale models of spokes, was it a windtunnel for ants? Spokes full size are not exactly large to test their different cross sections. Seriously, why would you bother making scale models of spokes and dealling with the problems of scaling wind tunnel tests? A Phd in physics could be very relevant to this or it could be completely irrelevant. Maybe your partner should be the one to talk about this and the data from your windtunnel tests is good, because you are making all sorts of weird statements that make me questions the testing.

Also, shape is still important if the flow is not laminar and a correct shape will reduce the flow even turbulent flow. In fact sometimes a shape works better with turbulent flow.

Thank you. I drink a latte every morning which leads to a pretty good burst of energy about 1 mile into my morning ride. By, the way, have been to the GM wind tunnel and the GM Quiet Room while discussing high current liquid cooling and balancing of motors, but that has nothing to do with bicycles, nor does it have anything to do with vibration analysis affecting wing loading during high speed cruising or landing at 160 mph. When you can safely ride a bike at 550 knots, please let me know how it felt.

"The wheel is constantly vibrating from road impact and the bicycle is constantly moving around, and that interrupts the laminar flow around it and the wheels and the tires and that creates a very high CRR, which instantly invalidates the test--the vibration disturbs all laminar flow. There is no way around it. The cyclist should choose their tires for how they feel to them."

Is this possibly throwing the baby out with the bath water? On the surface, it looks like you are arguing that because the system is complexity, no testing is indicative of relative improvements. If so, that seems pretty unscientific, and the recommendation to pick tires on a guess might be worse than using the test data available.

"Also, extensive testing has shown that thin round spokes are better than any aero spoke made (thus destroying the myth of so-called aero spokes)."

Can you cite any of the testing? I have read results from both Zipp and Flo that argues the opposite. I am curious to see what is different between the tests and papers you have seen versus those of a couple leading wheel makers. (They do agree that fewer and shorter are better than more and longer.)

"The larger the cross section of the wheel, then the more lean is induced and the higher the CRR of the wheel/tire combination. This flies against what most people are worried about on this thread, but it has been proven over and over again."

Are you arguing here that deep dish wheels are inferior to traditional box/aero cross section rims (except with very low yaw angle)? If so, could you reference any of the supporting data or studies. It seems like we have a plethora of examples of riders testing on velodromes and measured courses that validate wind tunnel results that deep dish are superior to traditional rims. Maybe some of the system complexity reduces some of the absolute advantage measured in a wind tunnel, but it seems the real life test examples do support the relative advantages.

Not necessarily faster, but different. Advertisers want to sell their wheels and so wind tunnel tests can offer a measurable and repeatable advertising statistic, in their wind tunnel. Aero wheels have their place. You find a smooth flat road with very little wind or even a head wind and as long as everything else is equal, the aero bike will win every time. Problem is, an aero bike is very specialized, it goes to hell and gone under different circumstances, such as climbing, rough roads and capricious winds, which as we all know exist most of the time. The rider has to choose and know what will work under different circumstances. That's all I'm trying to say here. Froome just won the last TdF time trial. Several riders didn't use aero bikes, he did. He won. His aero worked for him. He is also a very good cyclist.