[Closed] Deep Section Wheels?

I wouldnt expect you to notice much if any difference apart from cross winds being sketchier on the 50s.

I have 40mm wheels. Not any grief with crosswinds; not much weight penalty, and still look bling enough to make you want to pedal harder.

50mm will catch the wind more and you probably won’t notice a great difference at ‘normal’ everyday speeds.

But if you like them the go for it.

Go as deep as you dare depending on what side winds you think you’ll encounter. Though you pay a weight penalty for deeper section rims but they are stiffer. If you’re A heavier rider then the side wind effect will be less.

These days I don’t think 50mm is considered that deep. Modern rounded profiles are supposed to be better in cross winds that older straight triangular sections.

The aero benefits are probably small, but greater than the rolling inertia a few grams of Rim weight saving will give you - aero benefits apply all the time, inertia benefits only apply when you’re accelerating or braking. Both marginal gains but one is more marginal than the other.

If you like them, go for them. That’s all the reason you need.

Bit of a hijack - what's the thinking on mismatched rim depths?

Circumstances might lead to me ending up with lower profile front than rear rim. Is that the "correct" way to have it, if you have to? (front wheel being the one you don't want caught by wind?)

I run 82s on my TT bike. Doesn't take much cross wind to make that a handful passing gates etc. It's ok when there's constant wind but gusts make it murder

My new road bike comes stock with mismatched carbons 45 up front and 65 rear. Will update when it arrives but it makes sense.

Worth noting also that deep section wheels actually offer benefit to slower riders.

Straight on a deep section wheel offers almost nothing compared to a standard rim. Add ~12deg of yaw to that and you're saving 20% of the bikes drag.

An average rider spends most of their time riding at a greater yaw angle because their speed is lower relative to the wind (15mph speed vs 10mph wind on an average day?). The pro peleton on the other hand, unless it's a really windy day doesn't suffer anywhere near as much as they're doing 30mph in the same wind.

So the rider at 15mph is saving 20% of the drag (riding at 12deg yaw).

Double the speed and halve the yaw (ish), and the drag reduction halves as a percentage.

The downside of that is that drag increases with the square of velocity, so the 'average' rider is saving 5W off 25W of bike drag at 15mph, the pro is saving 10W off 100W at 30mph.

Circumstances might lead to me ending up with lower profile front than rear rim. Is that the “correct” way to have it, if you have to? (front wheel being the one you don’t want caught by wind?)

The front wheel gets more of ana advantage from being aero than the rear. But a disk front wheel would be unrideable outdoors!

Not sure it is only marginal gains personally, of course Depending what speed you ride at... I can notice a very perceptible difference, maybe 1-2mph when going from box sections to deeps. I happily ride 40s on the road bike in all but the windiest conditions and have used a 60-90 combination on the TT bike even in fairly breezy conditions. Rim design and shape is a bigger issue than absolute depth. I also find it easier to handle if you keep in an aggressive position or on the aero bars. If you sit up or stop pedaling you feel much more effect. Deepest always on the rear because there's no steering pivot over the rear, and your weight is over it. Even a disc has not given me any issues. Oh, and they sound awesome!

I have 62mm, 40mm and standard box section. I race on either weather depending. Personal preference is the 62mm just because they look better.
Performance wise, get the ones that look the best and will make you train harder. Yes there is a benefit for the aero wheels, but honestly it’s not like you will jump from averaging 20moh for a 50 mile ride to 22mph for the same ride.
Dealing with cross winds is also minimal drama, you quickly learn how best to deal with gaps in hedges, it’s easy, just like riding a bike. I don’t use my 60s in all weather but my 40s are on my winter bike.

There was a mag test that showed on a velodrome at 200 watts 50 mm rims were about 1mph quicker, which isn't insignificant.

I bought a set and my average speeds went up overnight. Whether this is important to a non racer is debatable, but shows you don't need to be putting out huge power to get a benefit.

Thanks guys, sound like there’s no reason to not get them!

Once you buys the wheels you then need an aero tyre. All depends on rim width, but there is some thinking that an oversized tyre on a rim will kill any aero gains from the rim depth. I run 23s on my deep (faster) wheels.

https://www.hambini.com/blog/post/bicycle-wheel-aerodynamics-which-one-is-fastest/

I run 50mm rims all the time on my road bike. I noticed a big difference going from the std wheels. Lighter and quicker. Out of interest what are u buying? After a bit of research I ended up with a pair of carbon speed cycle ones. They have been brilliant and i run them tubeless on 25mm tyres. No need for rim tape either. Think they were the sat ones. Worth a look for the money I wouldnt hesitate to buy another pair.

Once you buys the wheels you then need an aero tyre. All depends on rim width, but there is some thinking that an oversized tyre on a rim will kill any aero gains from the rim depth. I run 23s on my deep (faster) wheels.

Worth noting that on the wider rims (and pretty much all rims are now "wide") that the difference is <3W in most of the tests. Looking at rolling resistance tests 3W is about what you gain between 23c and 25C. Some 'aero' bikes even come spec'd with 28mm tyres now, so presumably they've been tested by the manufacturers!

Also there's the aerodynamics of the tyres. You don't want a smooth tyre (Schwalbe ultremo, etc) you want some tread, particularly on the shoulders and sidewall to help the airflow remain attached to the rim.

I'm looking at the 50mm Hunt wheels. Probably going to be running 28mm Pro One tyres.

Hunts are really nice looking wheels. Whether you will see any performance benefit with 50mm Hunts and 28mm wheels is debatable though. Look at the table in my previous link.
My shallow wheels are Hunt Aero, also nice wheels, don’t think they are particularly wide though. But for reference I use a 32mm tyre on my 40mm wheel, comfort over speed on those for me.
Schwalbe Pro One 25s on my rim is quite wide. I also like those as have them tubeless on the Hunts, and grip for me has been good. Lots of people complain about them in the wet and their longevity, but been ok for me.

my 50s are noticeably less prone to sidewinds than my 40s. I guess it's not all about depth but profile too. I use the 50s whenever i can because they do seem to feel a bit stiffer and I perceive that they better hold speed once up to speed. But mostly because they make a slight whooshing noise when cranked up

I need some for the velodrome. Currently got Mavic Open Pros on, and I don't think it's doing me any favours!

Whether you will see any performance benefit with 50mm Hunts and 28mm wheels is debatable though

I'm not really expecting any noticable performance benefit with them, I'm just being a bit of a bike tart and I like the looks of the deeper 50's rather than 30's 😀

Ah OK, I thought when you mentioned advantages of 50mm wheels, you were meaning performance advantages.
Also being a bit of a tart, I much prefer the deeper look. I do like the whooooshhh noise as well, I have Reynolds deep sections on my Aeroad, when I ride with a pal when he's on his Propel it sounds like a light sabre fight!

Any performance advantages would be much needed and much appreciated but not really expected.

A mate of mine has just bought some Giant aero bike with the deep carbon wheels on so that should make for an interesting soundtrack on future rides!