Newbie - Why aren't Aero section rims good for climbing?

I'm heavy, 95kgs and switched to 52mm aero rims from climbing wheels. The aero wheels are roughly 300 grams heavier and I'm faster over rolling / moderate hills. I haven't done any major climbs on them, but overall my average speed over a rolling 30 mile test loop I do which has a couple of half mile climbs at 5% is 1.5mph faster.

If I was doing some serious climbing in the Alps etc I'd probably switch back to climbing wheels, but that'd be mainly due to them being a bit more stable to side winds on fast alpine descents

British Cycling say the greatest climbing improvement you can make is to lose weight... losing a couple of kg will make a big difference for next to nowt, whereas as taking 2kg off a typical bike will cost you a couple of grand, at least.

Cruel but fair:

"Bodyweight
It’s no coincidence that the most explosive and best climbers tend to be rake thin. If you’re carrying a few excess pounds then, some sensible weight loss, is one way to guarantee better climbing performance. Don’t try to crash diet though as you’ll compromise your training and, if you lose weight too quickly, you could end up losing muscle mass, power and end up climbing worse. Nigel Mitchell, Great Britain Cycling Team Nutritionist and Insight Zone expert, gives advice about safe, sensible and effective weight loss during training in our Power to Weight Ratio feature."

Remember that Wiggo had to lose 10% of his weight to be competitive in the TdF.

They go on to say:

"Bike Weight
Once you’ve trimmed down your waistline, shedding some weight off your bike is a fun but expensive way to improve your climbing performance. Before you start obsessing about titanium bottle cage bolts though, remember that the most significant performance gains are to be had by reducing rotating weight. Upgrading your wheels is usually the bang for your buck most effective way to buy some uphill speed. Additionally lower spec and heavy wheels, relative to the rest of the bike, are a common way for manufacturers to produce attractive looking packages, so it’s not unlikely that your wheels aren’t doing your bike justice."

All at http://www.britishcycling.org.uk/insightzone/techniques/climbing/article... (may need to log in).

Having just built a pair of race wheels for a hill climb specialist...

The best way to climb faster is to lose weight. Unless you're an elite athlete, the chances are you can shift at least 5 - 10 pounds, and many could lose 20. Effectively this is the same as having a bike that weighs nothing or even floats. Plus you'll look buffer than David Hasselhoff in Baywatch. Cool, huh?

The next fastest way is position. Work on staying on the hoods or the drops if you can. Using the hoods offers a more aerodynamic position. After that, focus on tighter clothing; you'd be very surpised how much drag is created by a ballooning jacket that's too large, even at 15 mph. Getting an aero road helmet like a Giro shield is arguably one of the cheapest ways of shaving time.

Regarding wheels specifically, you can get down to 1,100 grams for low profile alloy clinchers for about 700 quid, but these would be for races only. Whether these would be faster than heavier, deeper wheels is dependent on a number of factors, such as:

1) gradient. The steeper the climb the more important weight (or lack of it) is. The lesser the gradient the more important aerodynamics is.
2) wind. Some places are a lot more exposed than others so deeper wheels are more likely to get pushed around.
3) direction. Deep rims work the same way as aircraft wings. Contrary to the above they are quicker on flats in a direct headwind, but as the angle of crosswind increases so does the likelihood they will stall. You won't fall out of the sky but the deep rim will cause more turbulence than benefit so will actually slow you down as well as cause instability.
4) road surface. Deep rims are stronger but more rigid. If your hills tend to be on poor tarmac then you're better off on shallower, more flexible rims.

That said, what goes up must come down and go across flats. Unless you live somewhere where there is a gale every other day then deep rims will be overall faster than shallow rims.

The best way to climb faster is to loose weight. The best way to loose weight is to get on your bike. One good way to motivate yourself to get on your bike is to get one with a lot of bling including aero wheels.

Read Michael Hutchinson's book, Faster, and specifically the section on aerodynamics and tech. He explains really well all the aero tech.
The biggest point you can grasp is that wind resistance increases with the square of velocity - i.e. the wind resistance increases exponentially the faster you go.
Apparently this is complicated at cycling speeds because we go roughly at the threshold speed for turbulent and laminar flow - so it's really hard to design components to have good aero properties in both.
Also, our big lumpy bodies are rubbish in terms of aero profile, and the frontal area of the bike compared to the frontal area of us is tiny.
The lesson being - work on your flexibility so you can ride with your back as flat as possible. That'll give you fairly big gains. After that, sort out baggy and flappy clothing. Then get an aero helmet. Finally, upgrading first wheels and then frame will all give you an extra half watt or so.
Basically, the bike bling makes no noticeable difference unless you're TTing on your own against the clock... and even then, a few seconds per km.
So just buy the wheels you want rather than agonising over it. Remember half the reason pro teams ride all the bling is so the sponsors can advertise and sell the bling. If it made much difference, they'd all be on very similar tech all the time (see aero helmets for sprint finishes).

I don't want to get personal, just to put it all in perspective regarding marginal gains. At 6' 4" (193.04cm) you have a BMI of 28.2, which is in the 'overweight' range:

http://www.nhlbi.nih.gov/guidelines/obesity/BMI/bmi-m.htm

The maximum BMI in the 'healthy range' is 25, so your maximum healthy weight would be 93kg.

To become competitive you probably need a BMI of about 22.7 (the average BMI of nine cycle racing champions including Merckx, Altig and Gimondi, see http://www.etape.org.uk/BMI1.htm) which means a weight of 84.5kg...

So just enjoy riding your bike! Don't worry about your weight, or your bike's weight, unless you want to race.

Back to the original question: there are two issues at play on a wheel when ascending on a bike. One is the rotational forces of the wheel. A moving wheel can help generate momentum, but it your stroke rate is slow and wheel moving slowly and unsteadily you're going to have to work hard to generate momentum and so the likelihood is that it will slow you.

The other is the 'aero' effect. Basically at lower speeds the benefits of aerodynamics are much reduced. There's very little point in slip streaming anyone at less than 12 mph. So basically the benefits of deep section wheels evaporate when going uphill and they only tend to make you look like you got lost on your time trial. As other posters have mentioned the pros don't use them on climbs, and cross-winds can be a problem.

These wheels have their place, but a solid set of Ksyeriums will see you round most things.

If you say they are strong, and you are heavy, then I think you have the most important point covered already. Bent spokes and out-of-true wheels spoil rides.

Another issue when you buy wheels is the whether the new true wheel is lemon or a peach. On a peach the new true wheel's spokes will have pretty even tension between themselves, but on a lemon the tension among spokes may vary by x2 just to keep the wheel true.

So if you buy the last wheel of type A on sale, be careful of the relative spoke tension required to make the wheel true.

If you are willing to accept a relatively heavier with higher spoke count but high quality robustness, consider a wheel-builder with whom you can get verbal confirmation that max spoke tension ration will be <= 4:3

I'll throw my 2 cents in.  There is no perfect all round wheel but a good quality aluminium rim with a reasonable profile might come close. Deep rims have a greater inertia but once powered up, maintain their speed better, which makes hill climbs a little inefficient as you constantly loading and unloading power.

side winds are only an issue with 60+ cm rims.  If you using a 40cm it's not that much of an issue under most circumstances.

as said before a light set of aluminium wheels would be good for climbing but if you on rolling terrain then a 40cm rim would be a good choice.

also as said, loose weight, get a power meter, a better helmet albeit there is no benefit when climbing, work on your flexibility and position change your cassette to a better hill climbing ratio.  You can improve your climbing with little or no money.

Even though it's a 2 year old thread, made for interesting reading, some clearly for deep sections, some for lighter rims, others extolling the virtues of proper training, surely the idea is to combine the best training that you can manage with the best wheels for the type of riding that you do? I'm no expert and don't profess to be but I research products by reading many reviews, on the product itself, more about quality and durability than claims regarding performance, because if you don't look after yourself and keep your diet and training to their optimum, then it doesn't matter what you buy, you are always going to be fighting a losing battle when looking for improvement.

When I purchased a new wheelset I actually bought a set a little bit heavier. The first ride out confirmed they felt far stronger and rigid than the originals. For me,the pedalling when climbing seemed far more efficient.

I know there are facts and figures showing that weight makes virtually no difference to climbing but I'd rather ride my 1500g wheelset than the 2000g one here in the North Pennines.

I have two sets of Campagnolo wheels that I use regularly - Zondas (which are not aero) and Bora One 50s (which are aero and also shod with tubulars).

The Boras are absolutely faster on the flats - I go faster for the same effort.  I do not notice any difference on the climbs and it has to be howling an absolute gale before sidewinds become an issue.

Braking is better on the Zondas, but it's not like the Boras are awful - I've done plenty of Alpine and Dolomite descents on the Boras with no issues.

Deep section aero wheels make your bike look good. But lighter wheels offer better bragging opportunities. For most of us this is where the discussion ends.

Does this inertia lark even have a real effect? Intuitively it doesn't feel like it; I can quickly spin up my wheels to a considerable speed (and stop them even quicker) by just lightly using my hands. Pretty sure I can't accelerate my body similarly with so little force. Seems absurd that a 300g difference between an aero and shallow section wheelset will make any noticeable difference. I probably pee out >300g of water on long distance toilet breaks yet I'm pretty sure I'm not faster up the hills at the end. I'd like to see the science proving me wrong.

The only way to settle this is to put some sort of cycling robots that can hold set wattage and body positions on different bikes and then see the true differences. Too many variables when humans are doing it.