Carbon wheels, why would you bother?

[Andrew_Culture]

Now here's an add thought; why would you bother buying carbon wheels if they are many times more expensive than aluminium and heavier?

I've been rim shopping (paging @fnar) and have been looking at these Campag wheels for a future project, they weigh 1550g and cost £229.

Whereas these Mavic carbon wheels weight 1630g and cost a whopping £2290! I guess they could have amazing bearings or something, but £2k worth of amazing bearings?

Am I missing the point?

 

[swee'pea99]

I don't know the answer, but I did read somewhere recently that 'weight', per se, is less the issue than weight at the rim. Most wheel weight-saving takes place at the hub, where it really makes very little difference - no more than weight-loss in any other (static) part of the frame. All that really matters is the weight you have to push around. (A friend who recently spent £600 on a wheelset reports 'bugger all difference, really') The piece I read said that by far the best bang for your buck comes from investing in lightweight tubes 'n tyres - the rest is mostly voodoo.

 

[Andrew_Culture]

Interesting, also makes sense. This is of course discounting @mattobrien 's research into new wheels making you faster.

 

[Koga]

Interesting, also makes sense. This is of course discounting @mattobrien 's research into new wheels making you faster.

Yes don't discount Matt's important research !

 

[Mr Haematocrit]

I find carbon rims to be a little stiffer in general which I like and if they have a reasonable rim depth and from a proven design you may get an aero advantage.

Having said that I just like them cost they look super cool and make a whoosh whoosh sound when you ride (im easily pleased)

 

[LimeBurn]

Because they look sexy of course!!

 

[Hacienda71]

Aero benefit is a major reason, although the benefits become more apparent at higher speeds. So an aero wheel at 15 mph isn't going to make much difference but at 28 to 30 mph in a TT it starts making an appreciable difference.

 

[Dusty Bin]

I don't know the answer, but I did read somewhere recently that 'weight', per se, is less the issue than weight at the rim. Most wheel weight-saving takes place at the hub, where it really makes very little difference - no more than weight-loss in any other (static) part of the frame. All that really matters is the weight you have to push around. (A friend who recently spent £600 on a wheelset reports 'bugger all difference, really') The piece I read said that by far the best bang for your buck comes from investing in lightweight tubes 'n tyres - the rest is mostly voodoo.

Rotating weight is largely irrelevant on any wheelset, except for some very minor (and very temporary) benefits. What matters more is the overall weight.

 

[LimeBurn]

Rotating weight is largely irrelevant on any wheelset, except for some very minor (and very temporary) benefits. What matters more is the overall weight.

I thought it was the other way around, rotational mass and unsprung weight is something you always need to reduce in performance cars so thought the principle would have been the same for bikes too.

 

[jowwy]

I'm staying out of this thread

 

[Dusty Bin]

I thought it was the other way around, rotational mass and unsprung weight is something you always need to reduce in performance cars so thought the principle would have been the same for bikes too.

I don't know about performance cars. It's true that a lighter rim will accelerate marginally quicker than a heavy rim - but it will also decellerate quicker. A heavier rim will take marginally more effort to accelerate, but will, in turn, decellerate more slowly. The two effects cancel each other out. It's one of Newton's Laws of Physics. Anyway, on a bicycle, you are not just accelerating the rim - you are accelerating the bike (and the rider), so the real issue is the total weight - not where the weight is.

 

[mattobrien]

Right then, time for my five penneth, it's like two penneth, but more...

1. Carbon wheels will be new, new = faster! proven by research

2. Likely that carbon wheels will be more expensive, expensive = faster (even if in truth they are slower)

3. Carbon are more likely to be aero, aero = cool + a nicer noise

4. Carbon wheels look better. I will forgive Andrew as he hasn't seen the difference between my bike from alu wheels to carbon wheels. That is my fault for only going on moist or wet rides with him and using the other bike.

5. Rotational mass. I will stumble into this one with a little past experience. My previous track car was a Caterham R500, it weighted in with about half a tank of fuel at 480kgs. The difference between the magnesium wheels and light slick tyres vs. standard wheels or even mag wheels with non light tyres was immense. Bearing in mind this car was light and had a genuine power to weight of 500bhp / tonne, you could very much tell the difference.

Rotation mass does matter, the lighter the better. A lighter overall weight will make getting up hills easier, but having lighter wheels to achieve this, will also make accelerating take less power and overall any change in momentum.

Even better if the carbon, lighter wheels are aero, as being aero they will take less power to maintain at speed.

A light non aero wheel out to take the same power to maintain as an identically shaped but heavier non aero wheel. But the advantages of the light wheel is the easier change in momentum, accelerating and braking. The heavy wheel will have more momentumn, so in theory will slow down lass quickly, but I don't necessarily see that as an advantage, especially if they take the same power to maintain at any given speed.

A light aero carbon wheel will take less power to change momentum i.e. accelerate, but will also take less power to maintain due to the aero advantages. Light and aero beats light and not aero. And light and non aero beats heavy and non aero.

That's my five penneth and some of it has even been scientifically proven...

If you are just going alongside flat at the same speed always, weight of wheels makes no difference, only aero will make a difference, but if you encounter any gradient or need to brake or accelerate then lighter comes into play, along with aero.

 

[Nigel-YZ1]

I'm staying out of this thread

So am I. Don't know nowt about carbon wheels

 

[jowwy]

Right then, time for my five penneth, it's like two penneth, but more...

1. Carbon wheels will be new, new = faster! proven by research

2. Likely that carbon wheels will be more expensive, expensive = faster (even if in truth they are slower)

3. Carbon are more likely to be aero, aero = cool + a nicer noise

4. Carbon wheels look better. I will forgive Andrew as he hasn't seen the difference between my bike from alu wheels to carbon wheels. That is my fault for only going on moist or wet rides with him and using the other bike.

5. Rotational mass. I will stumble into this one with a little past experience. My previous track car was a Caterham R500, it weighted in with about half a tank of fuel at 480kgs. The difference between the magnesium wheels and light slick tyres vs. standard wheels or even mag wheels with non light tyres was immense. Bearing in mind this car was light and had a genuine power to weight of 500bhp / tonne, you could very much tell the difference.

Rotation mass does matter, the lighter the better. A lighter overall weight will make getting up hills easier, but having lighter wheels to achieve this, will also make accelerating take less power and overall any change in momentum.

Even better if the carbon, lighter wheels are aero, as being aero they will take less power to maintain at speed.

A light non aero wheel out to take the same power to maintain as an identically shaped but heavier non aero wheel. But the advantages of the light wheel is the easier change in momentum, accelerating and braking. The heavy wheel will have more momentumn, so in theory will slow down lass quickly, but I don't necessarily see that as an advantage, especially if they take the same power to maintain at any given speed.

A light aero carbon wheel will take less power to change momentum i.e. accelerate, but will also take less power to maintain due to the aero advantages. Light and aero beats light and not aero. And light and non aero beats heavy and non aero.

That's my five penneth and some of it has even been scientifically proven...

If you are just going alongside flat at the same speed always, weight of wheels makes no difference, only aero will make a difference, but if you encounter any gradient or need to brake or accelerate then lighter comes into play, along with aero.

i'm sure @Dusty Bin @Rob3rt @T.M.H.N.E.T will be along soon to disprove all of this with their superior technical knowledge and lamblast anything you say to negate their argument

 

[User6179]

i'm sure @Dusty Bin @Rob3rt @T.M.H.N.E.T will be along soon to disprove all of this with their superior technical knowledge and lamblast anything you say to negate their argument

Knew you wouldn't stay out this thread !