There are deep section aluminum wheels and the additional weight makes almost no difference. You can make a Tour bike out of aluminum with aluminum wheels at the UCI limit so why is there any push for super expensive carbon wheels and frames? Most of the ride quality is the tires. If you like throwing your money away that's fine but I ride steel and if I'm concerned about weight, I ride aluminum. Look up the old 8 speed Campagnolo Shamals. Or the newer Pro Lites.
Recently at the end of this season, I hung up my $2.7k carbon clincher rims and went back to the aluminums that came with the bike. I warped the front carbon during a huge decent so I wasn’t happy but knowing it was covered under warranty I really didn’t care. However only 2 years of warranty exists on most brands. Anyway,, after going back to the aluminums, I did a killer solo 100miler with about 6.5k of hills at around 17.3avg speed, one of the most epic rides of my life. Then, the following week, I took off 1.5min on my PR up a 2 mile climb. Also very important to note that I became a monster in downhill cornering because the braking was that much better on the aluminum. I had gotten so used to inferor braking with the carbon wheels that when i went back to aluminum, i felt like a different rider. Back to the warped one, I got a brand spanking new carbon replacement under warranty, after kicking and screaming, and guess what? I’m not going back to carbon on that bike because of the rim braking. Knowing what i know now from this before and after experiment, I would have not "upgraded" ....If money is tight, stick with the aluminums and don’t invest into carbon, however..carbon hoops and rim braking is a stop-gap combination until disc technology dominates. The carbons feel like velvet however. In the end it’s all just marketing hype to sell merch to the mass consumer market. On the road, I often get blown away by people with entry level bikes and I’m often as strong if not stronger than some that are riding $12k rigs. Genetics and consistency dictate,, where money and gear can’t compensate.
Carbon rims save "30 secs over 40km at 40kph" - "cor, that sounds a lot!" I don't think so !!! Stop trying to justify carbon rims for any other reason than they look BLOODY SEXY!!!!
Anyone who can keep that speed up for that long deserves them. I'm pretty sure for the vast majority of us that stamina is way out of the question. But Yes, they do look Stella.
martin brown I’ve had that same thought on my FLO wheels. The surreal moment when you are standing on the cranks and the odd whistle that carbon makes is distinctive. Great observation to describe what makes them worth the price. But the cost of bladed spokes is also a bit pricey. ... Well if you jam the dropout into them at high speed... #whoopsie
I never noticed my carbon wheels making sounds at any speed. Maybe you have the hearing of a bat. Or maybe you have a tread on your tires that matches the oscillatory frequency of your wheels.
The reason for deep rims being made from carbon is not that the alloy rims would be too heavy, but the fact that it would be hard (almost impossible) to make them (winding deep alloy profile into a circle causes wrinkles).
I upgraded the 2.2kg alloy wheel set on my Giant road bike with 1.5kg carbon Prime wheels from Chain Reaction. The difference on any sort of up hill gradient is night and day. Sure, climbs still hurt, but now I only feel like I’m fighting my own body and my own fitness, not fighting the bike itself.
You’re just making yourself less powerful. If you’re cycling to be fit and healthy then stop trying to make your bike lighter. If you’re cycling to win races and pay your bills then fair enough
You did well, but you would sense about the same with good alum wheels just a few grams more, you would still make the wheels lighter by 0,5kg, and a hub more effcicient.
All the aero gains and aero talk is nothing but a marketing scheme. people who cannot hold average speed of over 30 km/h for 100km should only think about getting a right frame size and proper fit for comfort so they can maximize their power output. instead of thinking about better bikes and carbon wheels or slamming their stem just to be more uncomfortable and possibly slower. honestly if your 5 minutes interval speed on flat road doesn't exceed over 40km/h you don't even need a race bike. get an endurance bike. it would be a better training tool for developing power because it's more upright and comfortable. they exist for a reason.
The science says otherwise. Aero gains make a huge difference, even to those that can 'only' average 20kph. You don't have to spend a lot or be uncomfortable to be aero, just make well informed equipment choices. You'll get way more value for money (and speed) than by buying 'lightweight' products.
Haha, totally agree... unless your racing non-draft races and holding 40km/h through out it wouldn't make sense to have deep section wheels. As soon as there is drafting, that 30 second advantage over 1 hour will not mean anything unless your the one pulling everyone the whole time. Just spend the money on a bike fit, get the right set-up to your body and you'll do better than what wheels can give you. Nobody likes snapping wheels in half on a crash, save your money...
rararroro 100 kms that's open ended mind you. If you do a flat ride it's easier to.keep an average of 30 kmh. If I do lots of country hills and busy traffic on the back end my average comes off 30 kmh. If anything my carbon wheels my average. I can buy alloy disc wheels in 24h.but.the sub 1500g sets are getting into cheaper carbon. I.just like the ride feel.If carbon.They just don't flex when climbing.
snowJT if you're worried about snapping.wheel rims don't ride a carbon frame or fork, seen frame and forks crane yet carbon wheels were fine. Tbh if you race or ride fast groups and you aren't well.off.best to ride, alloy, steel or titanium and alloy wheels.
Jon, dead right mate. Unless you have a budget of over £1k stick to aluminium. For most of us average riders there is no significant performance gain (average speed 40km/hr - right!).
My beloved Canyon Endurace SL 7.0 Disc - yep that's right, 105 group set baby, and proud of it - came with ever-reliable, durable DT Swiss Alloy wheels. They're friggin' awesome. Are carbon deep-dishes more, ya know, eye-popping? Yeah no doubt. But I'm both happy and impressed with my bike as it came. If I accidentally catch a pothole, I don't worry the way I might with carbon wheels.
And the difference between the trimax 30 and Metron 55...about £1,200. Yeah, I'll stick to aluminium and get a turbo trainer, and have a couple of cycling holidays.
I have a set of Dura-Ace C24s. The rims are aluminium alloy with a CFRP (carbon fibre reinforced polymer) laminate on the inner surfaces. They weigh in at about 1420 grams, which means they are nearly 500 grams lighter than the stock wheels that came with the bike, so that's huge. None of the aero benefits of a deep section wheel, of course, but I simply do not ride that fast, and there is no question that the lighter wheels have contributed to me to keeping up at speeds I just couldn't manage before. The best bit is that I got them second hand from someone who was upgrading to full carbon deep section wheels so I got them for a little over 50% of the original retail. So yes, the rest of you lot go out and buy really cool wheels and I'll be waiting around for your hand me downs.
I have 2 sets of them for daily riding and a Dura Ace Carbon set. I'm more and Indian not the arrow kind. Hard work pays dividends. Too light things break. I avoid carbon like it has Cooties now. Ride daily on gravel. Need reliable equip
I've got a 30 deep alu front for stability and reliable braking with a 66 carbon rear for a little bit of aero. Perfect combo for rim brakes if you ask me.
Carbon bike parts, you don't need them, but you want them anyways But really: Go for alloy rims. They're better for your wallet and for the environment.
I just picked up a pair of Hunt alloy wheels that weigh less than those carbon Visions. They're not deep sections, but that doesn't really matter when you live in a hilly area. They feel really peppy when climbing, and they were actually affordable. They have a great freehub sound, too.
@@deivytrajan They're great - just did a slight true on the rear, but they've been an amazing investment. I'm running them tubeless with some GP5000s. I wrecked the front rim in a traffic accident a couple years ago, and Hunt customer service was incredibly helpful in getting me a replacement quickly.
Back in the day I was one those crazy city couriers and would destroy wheels all the time, so I taught myself how to build wheels, it's not too difficult and very Satisfying, and a good skill to have. I sourced the parts on line and built my own 50mm rim carbon wheels for less than £250. They're light and stronger than I thought they would be. All the info you need is on line. Personally I have found that hand built wheels are stronger and fast as or faster than expensive off the shelf wheels that I've bought. Do a little research, build your own wheels, it will put a smile on your face.
@@kpsig they're pretty readily available to be honest, wiggle & sigma sell rims only. You'll save some change. I'm going to Starr building my own wheels
i recently picked up a pair of carbon dt swiss rc 38c db basically brand new (demo) for a nice price. at ~1425grams they are around 300gram lighter than my aluminium ones. while i can´t verify this they seem to be a bit "livelier" when accelerating. its not night and day of course, but noticable. i wanted to switch back to the stock wheels for winter, but it felt somehow draggy. so they stay on. they are also more comfortable than the OEM Rose ones that came with the bike. but lets be honest, the real reason i bought them was the looks :D
Carbon wheels are generally stiffer laterally and more compliant radially. Since changing to carbon, I have found the steering to be more precise and the shock-absorption to be better.
In regards to stiffness, rim depth and spoke bed location are very important. For example, my Reynolds 72 Aero wheelset is 72mm deep and the spokes are bedded at the innermost edge of the rim. That means the spoke nipples are located roughly 60-70mm from the outer edge of the rim. Now, on a full carbon rim that aims to be as light and Aero as possible, this is an issue because the wheels become very floppy when sprinting or railing up a climb. In my 25mm aluminum Bontrager wheelset, however, the spokes are bedded very closely in relation to the outer edge of the rim (roughly 10-20mm). This means there is less surface of the sidewall that can flop around under load.
I’ve recently sold my Trek Madone 9.8 w/ carbon Aeolus 5 wheels. And, went to a aluminum bike with aluminum wheels, found good success racing. But, nothing beats a Super Bike w/ carbon wheels.
I have a pair of high end aluminium wheels with titanium spokes on a Columbus steel frame bike with rim brakes and I wouldn’t change it for any carbon manufactured bike. It’s light, comfortable and incredibly quick.
Carbon frame and good aluminium wheels is the best mix for a social rider. Would love to have the power for better wheels, but simply a waste of money.
My 2 cents. I like to climb. Weight matters. My aluminium wheels are 1410g. Got some carbon wheels as well (1480g). Carbon wheels do not brake well with rim brakes, and less so when it gets wet. Carbon wheels work only well with disk brakes. Disk brakes add between 250g and 500g to the overall bike weight. Why again would I want to do that ? Carbon wheels look sexier. I know. I have enough time looking at them while waiting for my mates riding carbon wheels, slowly, uphill ;-)
A lot can be said for simply upgrading from the stock alloys to some alloys which simply weigh less. Little more speed for little less cheddar. Not to discount carbon hoops; they make you go fast and look fast! I have been wanting some Reynolds R4s for a while now!
Good morning GCN, It is thought that GCN is one of the best channel for all cyclists! In my view, i just wanna see the subtitles in every video. Thank you!
Appreciate the good detail and generally practical approach. I've got deep carbons on my tt bike and alus on my roadie, and I'm perfectly content. Seems like a lot of people out there think they're gaining like 4mph by switching to deep wheels, which is obviously just silly. Nice to see a more pragmatic approach.
If I was a tour de France rider I would want the best, fastest and lightest. My alu rims work beautifully, it's shimano whr550 rims which is not the newest wheel on the market but it works for me, and I'm still on an old raleigh RC 6000 alu frame with 105 groupset... The geometry just works for me. But I respect that carbon is the present and the future. Alu still has a place in cycling
You should make a comparison of a top tier alloy wheelset around £1k (e.g. Ksyrium SL or a high end DT Swiss PR wheelset) with a comparably priced carbon wheelset.
I use a 42 mm high aluminum wheelset and with 1,85 kg the weight is still ok.... but they are tough to ride, have absolutely no suspension and are only made for perfect roads. Fortunately, I have the privilege of having 125 km of the best cycle path in Germany right on my doorstep.
I've ridden a set of Aclass cxd4's on my tiagara equipped Spesh Diverge which cost me $250 Cdn. Sub 1600g and have been bulletproof over 2 seasons riding road/gravel/cross. Saved 500 to 600 grams over stock. Feel stiffer and livelier and are the best upgrade. I'm not a lightweight either at 85kg.
The cost/benefit analysis of getting a cheap carbon wheelset that weighs just as much, if not more, than the Campagnolo Shamal Ultra wheels I chose wasn’t to the carbons advantage. For less than cheap carbon, the Shamal has ceramic bearings, carbon fiber hub body and bladed spokes that provide a stiff and responsive ride.
Good quality Alloy wheels are fantastic. Great braking, fit and forget. By the time the rims are worn out your hubs, your spokes and nipples probably will be too so is really of no concern. My aero and wide Carbon wheels are fast but braking on rim brakes is much inferior to alloy, and I'm constantly aware I'm wearing the braking surfaces out. Also my alloy wheelset is much narrower so have to adjust the brakes completely, so usually don't bother and just ride my heavy slow commuter roadbike if its wet or I'll be doing lots of descending, which isn't as enjoyable.
I bought into the carbon wheel hype. I picked up a pair of 2nd hand set of Bontrager XXX Lite's. I was running a set of Pacenti SL23's. I am a casual rider the only reason for getting the XXX's was the $200.00 price. The wheels are similar in depth 24mm but the SL23's are 23mm wide vs the XXX's 19mm wide. Both fitted with the same 25mm rubino tires I didn't feel or notice any real difference. The SL23's weighed appx 1500g and the XXX's 1200g. I didn't even feel the weight difference. The braking on the XXX's with bonti cork pads is surprisingly not much different than the SL23's with basic shimano pads. Please note this only my layman observation on non aero wheels.
Yeah, way too much product placement. Did anybody count how many times they said Vision or the wheels were visible? For me over the verge of being annoying...
@@Bungle2010 id buy that if they didnt namedrop every 15 seconds. Look at canyon for example - they usually just use their bikes and thats about it. This one is definitely paid for.
These guys are getting painful with their sponsored segments. They didn’t mention many positives about aluminum which is a shame. Most cyclists don’t need carbon. I have several custom aluminum wheel sets and they are bulletproof and cheap to fix
I bought my bike on a budget. MASI bicycles does, however, use the same exact frame for their entry level VIVO road bikes as they do the top end ones... they just change the components and the paint job to match the level you buy. That being said, by switching from the low end alloy wheels the bike came with, I stand to save a ton of weight on the bike and really wake it up a bit.
can you review a tommaso bike? They make high quality bikes that compete with companies like trek and specialized with a much cheaper price tag. I own a bike from them and it is absolutely amazing. I feel that a review from you guys would help out the company a boatload!
@Nate Dog My point was that the video mentions what they consider to be two cons of carbon wheels, despite the comment above saying that this wasn't the case. Since you mention it though, in my experience (which may be different to yours) disc brakes are indeed stronger, especially in the wet. Cycling is all about compromises though, and rim brakes are considerably lighter, which may explain why the pros still use them. For what it's worth, when I bought my "best" road bike, I made a point of buying one with rim brakes due to the weight (and cost) saving. My cyclo-cross bike has disc brakes though, as they give me more confidence off road, as well as on road during winter months.
I often hear the statistic. A deep section wheel will save 30 seconds at 40kph over a 40 km distance. Only a small percentage of people could average that speed over that distance. So a no nonsense statistic for most of us.
The wheels must save at least 30 seconds or it's not worth it. To get the savings so large, the distance and speed also must be large. The average rider on a after work ride will save so little... Still, if you like it GET IT!
My vision metron 40 carbon wheelset on a scott foil full carbon (7.3kg) is only 0.2mph faster than my ultegra alu wheelset on a kinesis steel bike(10.5kg)on the same course, the same distance, roughly the same weather conditions and most importantly the same average power. Carbon looks cool but doesn’t necessarily makes you a lot faster. Unless you are racing for a podium or gc contender on a world tour then a few seconds help.
I've got a Scott Foil 10. First generation carbon 3T 62mm tubular wheels (crazy cheap in the States since everyone's going since everyone's going tubeless) gave me aero advantage and handled unbelievably well, super light. Zipps didn't handle as well on the foil, but held their speed well. 3T's were stiff and broke, so bought some 45mm Pancini carbon tubular, the handling's back, and get up to speed and hold it great. Black spokes and hubs give them a stealth look, I'm happy.
Just came across this video. And I’ve seen every available video hyping disc brake compared to carbon rim braking in the rain. And yet I’ve never seen a video comparing disc stopping vs aluminum rim. Would love a disc bike but can’t justify it.
I’ve said this every video I watch there’s so many electric vehicles now it doesn’t even need to be an expensive one could get a Nissan Leaf film with the boot open
Mavic Ksyrium ES (aluminium) for me, 1520g. Light enough in the mountains and safer with rim breaks. Mavic used to only recommend aluminium rims in the Alps. Incidentally noticed a warning on some DT Swiss carbon wheels, not to position close to car exhausts! Obviously concerned that long periods of heat exposure (while transporting bike) could affect rim structure! ... Carbon still look the best though.
"30 secs over 40km at 40kph"? What if I sit in the bunch for most of the race? I bet the benefit is negligible. It won't affect my positioning in the bunch, and the difference in power required to stay in that bunch with either wheel is also negligible. I will just go for a stiff aluminium wheel, thanks.
Steel is best with leather lined brake blocks, preferably rod operated, maybe with a drum brake at the rear. They can be straightened out with pliers plus you can always cut a chunk out and re-weld them, e.g. if you had a 700c tandem wheeled bike and wanted to go for a 26" mountain bike instead. With steel wheels you also get the most out of training rides, it is cheating to go out on a bike weighing less than is proper.
People say you only go 1-2 mph faster. I also thought,you save a watts . So if your into racing, it's worth it. I also want to upgrade my wheels to make my bike accelerate faster.
what i would really like to see is a test between an old style Low profile time trail bike and a top of the range new carbon time trail bike on the same course i.e g10/42 like you did before with the other mob,maybe get a lotus 110 to,all ridden at the same power of course with the same tyres.
The lighter the rotating mass the less gyroscopic action. This can make a huge difference in stability or ride feel. It takes more balancing than with a heavier set of wheels.
Great to know the difference is not much other than the things you would think. -> carbon is a bit lighter, but simultaneously more expensive. And that very deep wheels, that would cost a lot, make sense only when you are quite a pro biker anyway..
Speaking as someone who is not a skilled rider, I have just switched to a carbon frame bike with carbon rims, and I have noticed that the new bike is a little less stable than the old one, and I believe it’s at least partially due to the lower moment of inertia of the rims. This may be less of an issue for a more skilled rider.
Just got a set of Rolf Ares LS carbon wheels to replace a set a Easton EA 90s. The wheels do spin up much faster and I noticed that they maintain momentum better when spinning. I gained about 1.5 mph avg speed on my last ride. Lastly, I’m more comfortable when I ride due to having wider rims and 25c tires.
I’m new to cycling. Riding on Swift and will be going outside in March. Went for a full carbon bike and wheels because it looks good. And when you look good, you’re half way there. Also went for the black/red look because of these 2 guys.
Well that was all the convincing I needed.. I'm sold !💵💵 Get those carbon deep section disc brake wheels in the cart🛒! Okay, so on a more serious note it is cool to have a comparison but its not totally fair as you cant do the same thing both materials. There are limitations to both... Carbon is at its best using it for deep section aero wheels with disc brakes and aluminium are best for hard wearing wheels for roubaix or nice climbing wheels with excellent braking....horses for courses 🐴
Hi team GCN , I just wanted to say I was a bit afraid GCN wouldn't be GCN anymore when all the new presenters came, but I wasn't right at all. The new ones are lovely personalities and the combinations off them work well just like before. I am glad a few of the old bunch sticked though.
These expensive deep section carbon wheels are all about marginal gains. Shaving off seconds when it could be the difference between you winning a TT/ race or not. Great for the pros who can really turn up the pace and need the best performance to match. For ordinary road cycling, they're absolutely pointless unless you're really that concerned about fashion. A decent set of all round alloy wheels and tyres will serve you better.
You have compared the weight of some crappy entry level aluminum wheels to $2000 carbon wheels, good job. You can easily find solid sub 1500g alloy wheels that will still have a very competitive price compared to carbon wheels. Of course, carbon wheels are lighter, but I don't remember ever seeing 2000g alloy wheels. Even very basic $200 Mavic Aksium are 1850g. The main difference is that, while doubling the price, you can have 50-60mm deep section carbon wheels that weight roughly the same or slightly less than high quality 30mm alloy wheels. The comparison should be: 1. 30mm alloy wheels to 35mm carbon wheels - the price of carbon wheels is roughly double and you can gain around 100-200g in weight, so the question is - is 200g difference worth double the price? 2. 30mm alloy wheels to 50mm carbon wheels - the price of carbon wheels is roughly double and the weight is roughly the same, or the price is more than triple and the weight is 100-200g less, so then the question is - are the aero gains worth double the price, or are the aero gains and weight savings worth triple the price? Look, carbon wheels are nice and I am riding them myself, but let's be honest and keep things real. Comparing 2kg alloy wheels (that I have never seen) that cost $200 to $2000 or $3000 top-of-the-line carbon wheels is not a fair comparison.
I got my bike with an optional 'superduper' Scope carbon ( € 1.400,-) wheelset. I am not gonna say here what I think of them, but fact is that in a few weeks I will be riding alu DT Swiss 1600's 32mm (€ 500,-). Looking forward to it.
I have dt swiss pr1400 dicut oxic disc brake wheels......i have just bought some Hunt 40mm aero disc carbon wheels. I cannot believe the difference once you get above 25km/h,the wheels give a feeling of aiding your pedalling and they roll far better than the dt swiss,especially on shallow rolling roads,if you are thinking about going aero carbon i would say go for it
Saving 30 seconds or so over 40 kilometres is nothing and is totally not worth the money, unless you are doing Time Trials. Carbon Wheels for everyday riding or even club runs is totally not worth it, unless of course, you care more about how something looks and don't want to feel embarrassed because you don't have deeper section wheels.
My son started cylcing Jan 2019 he races and on average does 180-250 M a week he is 15 he has a Specialized Allez sprint Got him a pair or cosmic elite alu ok, saved 600g over the standard wheels but dropped on a pair of little used second hand American Classic 38mm carbon tubulars what a difference they are generally kept for the races with the cosmics as back ups but in total 1.1KG weight saving over the standard wheels, if your still on rim brakes look out for second hand ones as people change to discs
3:37 They are saying that rotating weight is important here in this video, and later they made another video debunking the "myth of rotating weight"... What is worse, their example in this video is criterium, on which the debunking video's research was done. I support this video and completely oppose the other one.
Maybe I missed it but you don't cover one of the most important topics in my mind. STRENGTH and ENDURANCE. Are the carbon wheels as "bullet proof" as alloy? Am I going to hit a pot-hole and crack my carbon wheel, whereas my alloy wheel powers on and survives another 6,000 mile riding season? My Aluminum Fulcrum-Racing-One wheels have 19,000 miles on them. If you're just an amateur rider with no racing concerns, 30 seconds over 40Km is irrelevant. But a cracked rim from a small pot-hole that requires buying a new wheel? -- that matters!
You can good alloy wheels at the same weight as deeper carbon wheels. Deep wheels might be great for faster riders or racing. That is not me, and not most of us.
Basically unless you ride at pro level speed for pro level distances, you wouldn't be fast enough to get a faster time with aero rims. If you could, you would be pro and be getting them for free anyway. It's like putting a big rear spoiler on a golf cart. So for 99.9% of riders, it's function would be purely cosmetic in effect. The metric for getting faster is body and bike weight.
My Mavic Kysium SL alloy wheels weigh less than the Mavic Cosmic carbon 40, so I havent noticed anything when climbing. I ride on fairly crappy roads too and to true the wheel costs about 20 euros. I agree that carbon deep rims are probably faster for an am rider like me!
A few Mavic aluminum wheels are lighter than many carbon wheels. I have in my bike a Vision Comp Team 35. It looks good and on descent goes faster than few carbon wheels in my friends bike.
I have two bikes with Mavic Kyserium Pro SL Exalith wheelsets. The Hub Doctor freehub kit is an easy for the plastic freehub bushing and the Exalith brake track is on par with any disk brake bike I've been on. And the weight is about 1350 grams for the set. Great wheels!
I built an aero bike from ground up for about $1,700 US including tools ilink aligator cables, fsa k force microshift sella italia slr s3 time xpresso and 38mm aero rims etc etc comes in around 16 lbs. It was fun to build the bike, and i feel like I own every ride. I dont care if I PR but I can tell you its much faster than my canondale Six13.
Everybody in the comment section just confirmed what I’ve always suspected. There really is no difference between aluminum and carbon wheels. I’ll spend my money on a new group set instead.
And all aluminum used for bike components are aluminum alloy. It has been used as a synonym for ages, we need to change it when titanium gets more popular though.
Hmmm, when mentioning aluminium wheels they say “kilograms” but when they mention carbon wheels they say “grams.” 1000 grams is one kilogram. So the carbon wheels weigh 1.5 kilograms and the aluminium ones weighs 2000 grams.
Question lads: What are the gains to be had, if any, to carbon wheels over 40k at an average speed of 30km/hr?? (This is unfortunately more like my average speed!!)
hi Ryan. The Specialized people have a number of videos where they look at various things you can do to improve your speed aerodynamically. Changes to the bike and even shaving your legs. They quote their improvements as minutes or seconds over 40km. They say that the times are the same no matter what your speed. This is because even though the aero advantage is greater at 40kph than at 30kph you are out there longer so it evens out. So the GCN guys will see their time go from 60 mins to 59.30 and you will see yours drop from 80 mins to 79.30. You have to consider whether spending $1000 to save 30 secs is worth it. I don't think so but each to their own. Carbon wheels are certainly popular.
