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

by PaulBox   May 19, 2014  

Hi, sorry if this is a really stupid question, but I'm currently thinking about buying some new wheels for my road bike and can't find the answer elsewhere.

I'm considering a set of Pro Lite Bracciano A42's because they are supposedly strong (I'm a big lump), have the upside of being aero and look quite nice. Obviously not a sexy as their carbon equivalents, but due to being heavy I don't want to risk getting carbon wheels at this point.

What's putting me off is that I keep seeing references to aero section wheels not being good on climbs and in windy conditions. The windy conditions bit is self explanatory, but I can't see why they would be detrimental to climbing. Being a big lump I certainly don't need any other hindrances on climbs...

Thanks in advance for help/advice, Paul.

44 user comments

Latest 30 commentsNewest firstBest ratedAll

vorsprung wrote:
the lower rotational weight, especially on climbs is helpful. For beginners this is more likely to be the case. So it's possible that light wheels could actually give someone with a poor pedalling style a small but measurable advantage on climbs.

Measurable? I doubt it. We're talking about tiny micro-accelerations within each pedal stroke. An improvement in pedalling technique (and choice of gears, if possible) will be far more beneficial. Lighter, fast rolling tyres and lightweight inner tubes would be a better bet.

vorsprung wrote:
Secondly, the 1%-1.5% figure for aerodynamics only applies for time trialists moving at 25mph+ who have presumably already adopted an aerodynamic position. For general riding any effect is unlikely to be noticeable at all
The numbers are from wind tunnel tests of just the wheel and tyre. The aero effects still exist at lower speeds since physics doesn't change from 15mph to 25mph. But I agree, it's meaningless for general riding.

700c wrote:
It's basically personal opinion. This has been covered many times before and there are a couple of usual suspects here who always come out against aero/ lightweight wheels - or perhaps the idea of someone else spending what they consider to be a lot of money on equipment.

It's not my opinion, the numbers are consistent across a wide number of sources. We all like shiny kit but just because brand X says their wheels are fast/light/whatever doesn't mean you just buy it and automagically go faster.

Simon E's picture

posted by Simon E [1910 posts]
19th May 2014 - 16:18

like this
Like (109)

Thank you all for your inputs and sorry for opening this particular can of wriggly things...

It seems that this is the roadie equivalent of the Flats vs SPD's debate in my more familiar world of mountain biking.

posted by PaulBox [12 posts]
19th May 2014 - 17:18

like this
Like (107)

Simon E wrote:
The numbers are from wind tunnel tests of just the wheel and tyre. The aero effects still exist at lower speeds since physics doesn't change from 15mph to 25mph. But I agree, it's meaningless for general riding.

It's strange how the 'you have to be going fast to benefit' thing is so often repeated when it's not the case, as you can see with a play on here:

http://www.cyclingpowerlab.com/componentaerodynamics.aspx

posted by olic [8 posts]
19th May 2014 - 18:05

like this
Like (107)

I don't notice any disadvantage going up from either my low profile alloy tubs or the 50mm carbons, but if you're going up then generally you're coming down at some point. This is when I prefer to be on the low profile alloy rims, crosswinds hit harder when you're going faster and the braking surface is a bit keener.

posted by Nick T [763 posts]
19th May 2014 - 18:40

like this
Like (108)

I wouldn't buy expensive bike kit based on manufacturer claims, I'm not sure anyone is that stupid are they?

I also wouldn't base decisions on wind tunnel figures. You simply can't factor in real world and human factors.

The idea that anyone would neglect their own training or technique and rely on expensive equipment 'to make them go faster' is also pretty patronising in this debate, to be honest. Yes I like my carbon wheels, and I disagree with the 'you won't notice the difference' brigade, that doesn't mean I've bought some manufacturer BS or am relying on expensive gear to make me go faster.

I've just put on my summer wheelset and it's improved my ride and speed to a significant extent -ie I notice the difference and I'm setting my fastest average speeds of the year now.

I'm not claiming they'd be right for everyone, but certainly wouldn't be so dismissive of a different opinion like some are on here

posted by 700c [556 posts]
19th May 2014 - 20:41

like this
Like (109)

Strava tells a story of an average speed difference of about 2.6kph between winter bike (blue ribble / 11kg / 36 spoke low profile rims) and summer bike (carbon Ridley /8.2kg / variety inc deep section carbons). Right now, that is a comparison of almost exactly 3000km on each so quite a good comparison. So - something is making a difference, and its not just the legs!

posted by edster99 [148 posts]
19th May 2014 - 21:06

like this
Like (109)

i live in plymouth, and i have ridden 50mm carbons for the last 7-8 months. they look AMAZING!

(see my pic on the bikes stickey, tcr with 50mm near the bottom of the list)

but i am getting rid of them asap to get some rs81 or something similar as they are terrible in the wind, verging from annoying if you want to say take your armwarmers off to down right lethal in strong coastal winds.

and no im not a chopper, i race and have ridden for 20 years.

on a wind free day they are great, best things ever! sound amazing and all that.

but there are 2-3 routes which are always dogged with a perma cross wind and holding a straight line sucks the fun out of my ride.

i say buy them if your area is not inherintly windy but if you live anywhere windy like fecking plymouth dont waste your time

posted by russyparkin [579 posts]
19th May 2014 - 22:10

like this
Like (108)

edster99 wrote:
So - something is making a difference

The weather?

Noli porcum linguere

captain_slog's picture

posted by captain_slog [263 posts]
19th May 2014 - 22:30

like this
Like (109)

PaulBox wrote:
I've been told that aero section rims will improve average speeds on the flat by between one and two miles per hour, is that bull?

If you want aero wheels because they are shiny and everyone wants them, get it. But for the majority of normal people riding around they offer very little to no increase in performance. If you have money to throw around you are better off getting some lighter wheels. OR you have enough money to get wheels that are both light and aero.

pants's picture

posted by pants [72 posts]
20th May 2014 - 7:23

like this
Like (107)

My tuppence worth is that if you're doing a lot of climbing, you are likely to be riding in exposed conditions and deep sections catch crosswinds and pull the front wheel.

I don't have any proper 'aero' rims, but even at that, the deeper sections are noticeably more hassle on a windy day, not so much at high speed descending, but at low and medium speeds.

All Campag

posted by Flying Scot [480 posts]
20th May 2014 - 7:40

like this
Like (106)

700c wrote:
The idea that anyone would neglect their own training or technique and rely on expensive equipment 'to make them go faster' is also pretty patronising in this debate, to be honest.

Really? Many, many people are buying bike kit (often prefixed with the word "carbon" or "lightweight") simply because they can. For lots of cyclists training is not a priority, while having the 'right' gear most certainly is.

If you're happy with your wheels that's great. I really don't have a problem with it, and you don't need to justify yourself. I am merely trying to explain that the marketing guff and the real world can be some distance apart. Wind tunnel data is certainly not irrelevant, it's how people test aero performance.

Simon E's picture

posted by Simon E [1910 posts]
20th May 2014 - 9:59

like this
Like (107)

edster99 wrote:
Strava tells a story of an average speed difference of about 2.6kph between winter bike (blue ribble / 11kg / 36 spoke low profile rims) and summer bike (carbon Ridley /8.2kg / variety inc deep section carbons). Right now, that is a comparison of almost exactly 3000km on each so quite a good comparison. So - something is making a difference, and its not just the legs!

That may be true but unless you are using both bikes in exactly the same conditions it may simply be you travel slower in the winter than the summer.
My winter average is 1 to 2 mph slower.

posted by Wesselwookie [110 posts]
20th May 2014 - 10:25

like this
Like (105)

Wesselwookie wrote:
edster99 wrote:
Strava tells a story of an average speed difference of about 2.6kph between winter bike (blue ribble / 11kg / 36 spoke low profile rims) and summer bike (carbon Ridley /8.2kg / variety inc deep section carbons). Right now, that is a comparison of almost exactly 3000km on each so quite a good comparison. So - something is making a difference, and its not just the legs!

That may be true but unless you are using both bikes in exactly the same conditions it may simply be you travel slower in the winter than the summer.
My winter average is 1 to 2 mph slower.

Yeah maybe. Some of it (as has been noted) is due to the weather and dancing carefully round wet corners. But the other thing I notice is how much more effort it takes to drive the blue battleship round the corners and accelerate out. thats at least partly due to the lighter weight of the wheels. If I'm getting back up to speed more quickly, then that will help my average.

posted by edster99 [148 posts]
20th May 2014 - 10:35

like this
Like (107)

To the OP.
You may be over-analysing it.
It will make **** all difference to your average speed, acceleration and enjoyment of riding whichever half decent wheels you're going to choose, especially as in your own words you are a "big lump".
Pick the ones that look good.

I don't follow trends. Trends follow me.

posted by BBB [172 posts]
20th May 2014 - 14:46

like this
Like (105)

I started riding 50mm carbon clinchers on my road bike (though i bought them for windy days on the TT bike in Lanzarote). I can't say i've noticed the winds too much in the UK, but then on the TT bike I usually ride a disc and an 808 so may be i'm just a bit more used to it?

I love them. They look great, sound great, are lighter than my previous Mavic KSYRIUM Elites.

Buy what makes you happy!

dangoscomb's picture

posted by dangoscomb [5 posts]
20th May 2014 - 15:41

like this
Like (102)

Wesselwookie wrote:
edster99 wrote:
Strava tells a story of an average speed difference of about 2.6kph between winter bike (blue ribble / 11kg / 36 spoke low profile rims) and summer bike (carbon Ridley /8.2kg / variety inc deep section carbons). Right now, that is a comparison of almost exactly 3000km on each so quite a good comparison. So - something is making a difference, and its not just the legs!

That may be true but unless you are using both bikes in exactly the same conditions it may simply be you travel slower in the winter than the summer.
My winter average is 1 to 2 mph slower.

Colder air is denser...

glynr36's picture

posted by glynr36 [280 posts]
20th May 2014 - 17:15

like this
Like (103)

To be fair, I'm not really analysing anything, I only asked why they are not so good for climbing... Wink

posted by PaulBox [12 posts]
27th May 2014 - 9:35

like this
Like (61)

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

Argon18 E-112 - Scott Spark 910 - Boardman Team Carbon - Planet X XLS

posted by colinth [183 posts]
27th May 2014 - 12:26

like this
Like (55)

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).

posted by drmatthewhardy [299 posts]
27th May 2014 - 21:40

like this
Like (53)

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.

posted by Gordy748 [74 posts]
27th May 2014 - 23:23

like this
Like (53)

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.

posted by timtak [20 posts]
28th May 2014 - 0:33

like this
Like (56)

timtak wrote:
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.

I 100% agree with the principal that enjoying your bike makes it easier to get out on it, but I don't find that it helps me to lose much weight, probably due to the cake stops etc...

When I say I'm a big lump, yes I am overweight, but I'm also 6'4" so even at my fighting weight I'm still 105kg. I also agree that losing a bit of weight is the best way of improving climbing performance, I certainly notice a huge difference when I've knocked off a couple of lbs.

posted by PaulBox [12 posts]
28th May 2014 - 8:45

like this
Like (47)

Gordy748 wrote:
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...

I don't think that wheels that light would be a good idea given my weight. I'm looking at Zipp 30's at the moment, forgetting the aero section now as I want something that I can use every day, i.e. not worrying about wind etc. (I don't race or anything). They seem pretty reasonable value for a big brand factory wheelset. Do you think they would do a job for me?

Paul.

posted by PaulBox [12 posts]
28th May 2014 - 8:59

like this
Like (49)

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).

posted by bashthebox [619 posts]
28th May 2014 - 11:51

like this
Like (48)

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.

posted by drmatthewhardy [299 posts]
28th May 2014 - 22:43

like this
Like (42)

timtak wrote:
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.

Why can't you spell "lose" ?

posted by dreamlx10 [134 posts]
28th May 2014 - 23:42

like this
Like (41)

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.

posted by Colin Peyresourde [1086 posts]
29th May 2014 - 0:03

like this
Like (43)

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

Charlie Horse

posted by ch [100 posts]
29th May 2014 - 7:16

like this
Like (41)

bashthebox wrote:
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).

Just half? Devil

Ghedebrav's picture

posted by Ghedebrav [1026 posts]
29th May 2014 - 8:29

like this
Like (41)

drmatthewhardy wrote:
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

That just demonstrates how crap those charts are, when I was 105kg I had a 6 pack and was in top shape. I'm never going to look like a pro cyclist as my body shape just isn't right. Right now I'm unfortunately more than overweight... Thinking

drmatthewhardy wrote:
To become competitive you probably need a BMI of about 22.7

I'm not worried about being competitive, I just didn't want to buy wheels that were going to add to my struggles up hills.

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

Amen!

posted by PaulBox [12 posts]
29th May 2014 - 9:59

like this
Like (39)