Confused about weight and height of rims....

[Cif]

Hi all, I'm looking for a new set of wheels for my titanium roadie.

I usually ride almost flat terrain. When lookingbfor wheels I see that a 50mm wheelset is heavier then a 24mm set.

I now ride a 35mm ALU set with a weight of 1560g. Seems quiet weird to but a 50mm carbon set that 100g heavier, or am I wrong in this?

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[MisterNoChain]

It depends where you look. Some years ago they couldnt make full carbon clinchers, the rim couldnt handle the pressure. The WH-9000-C50 is the first full carbon clincher from shimano and weighs 1685 grams, thats a lot when you compare it to a 50mm wheelset from Farsports http://nl.aliexpress.com/item/Basalt-brake-surface-3K-matt-50mm-carbon-tubular-bicycle-road-wheels-only-1210g-30g-pair/690562060.html

Why cant shimano make them lighter? Do they want riders to buy the more expensive tubulars? Are they afraid rims wont hold if they make em lighter? Once a wheel is rolling a heavier rim will continue rolling more easily so is it necesarry to make the rims a lot lighter?

[efeballi]

Shimano DA C50 clincher is carbon/alloy laminate.
It is natural for deeper wheels to be heavier, there is more material on the rim. Farsports rims have full carbon construction and thus lighter.

MisterNoChain, the tubular is easier to design by nature and does not need walls that need to resist the tire pressure. The tubulars are a closed profile and the braking surface is supported by the rim bed, unlike the clincher braking surfaces. Ergo tubular rims are lighter than clinchers, mostly.


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[HillRPete]

It really depends what you're after. Some people prefer the inertia of heavier wheels, the "freight train" feeling of the wheel carrying speed. Others prefer the nimble feel of very light wheels, the "whip like" acceleration when getting out of the saddle on a climb.

[efeballi]

Freight train effect, that is why I'm using my 1900g RS10s


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[pushstart]

It is also worth pointing out that Farsports by default use really light Ed/Bitex hubs (~250g for the set) which I imagine is saving some considerable weight vs Shimano, but not at the rim [where it matters more]. The 50mm x 24mm Farsports rims I had were not themselves that light (~500g/rim, I believe) -- though I imagine that is still lighter than comparable carbon/alloy options.

[Cif]

Am I correct in assuming that a light wheelset (24mm) would cost less energy?
My main use for the bike is my 3x times per week commute of 30k.
And at 6 o'clock in the morning, I want to spend a minimum of energy.

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[aaric]

A lighter wheelset at the same profile would in theory use less energy on large climbs. If your route is flat, the weight won't matter.

The deeper wheelsets are going to be faster due to aerodynamic gains in almost every case.

[efeballi]

+1


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[Zen Cyclery]

@Cif- Like Aaric said a lighter rim may save you a couple watts on larger climbs, but in most situations in the real world it won't give you any noticeable energy savings at all. I prefer slightly deeper, mid weight rims seeing as they are a good balance of light and stable on the flats.

[Cif]

Ive had a Shimano RS80 set on my previous bike. On my new titanium bike, a 35mm alu wheelset is mounted.

If it isn't the weight , could it simply be hub quality that is slowing me down? (Drag in bearings, ...)
To get the same speed, I notice that I need more power then on my previous bike.

Geo and weight of the bikes are about the same.

[btompkins0112]

On shimano wheels the bearing preload is key.....once that is set correctly, they are some of the smoothest running hubs ever.

[aaric]

If being slower is in fact down to the wheelset, its also entirely possible the RS80 wheelset + tires is actually more aero than your 35mm aluminum wheelset + tires...Shimano's lower profile wheelsets have traditionally tested well aero wise.

However, its more likely due to your position on the bike, if in fact you are going slower...It's hard to notice differences by feel, really. Barring a wind tunnerl, or properly calibrated power meter and riding a known course multiple times with comparable wind / weather its almost impossible to gauge accurately. Much like in a car, you can feel faster by being lower, which might not in fact be the case. Changing out the whole bike, and trying to attribute your perception of speed to the wheelset alone is going to be a futile exercise.

You can also look at tires/tubes, and tire pressures, which have some bearing on speed, though more so on your perception of speed. Often times, a faster tire/pressure combination will feel slower, as its smoother.