Carbon wheels, why would you bother?

[Dusty Bin]

You are an utter moron.

and resorting to insults just demonstrates that you have nothing else to give...

 

[ianrauk]

@400bhp @Dusty Bin
Enough! Walk away.. both of you. If not, I can help you walk.

 

[400bhp]

Sometimes you have to tell it like it is.

Black and Yellow.

The sky isn't blue..

 

[andrew_s]

The fact that lighter rims will accelerate faster than heavier rims is understood and I don't think that is in dispute. But both riders will have performed the same amount of work to cover the same distance, regardless.

Not so.
My conditions were stated such that the two riders were still travelling at full speed at the finishing line, and therefore the rider with the heavier wheels had no opportunity to recover anything from the extra momentum his wheels had.

Yes, if the riders had cut off power at the correct moment to coast to the finishing line, the rider with the heavy wheels may have been able to cut power at the same instant as the other, despite being further away, and thus use the same amount of energy.
However the challenge was this

There are no circumstances under which two identical bicycles (with differing rim weights) ridden by identical riders, using identical power, over an identical distance, will use a different amount of energy.

, so I provided some circumstances, nice and simple with no gravity or acceleration other than at the start to complicate things.

In general, heavier wheels mean you have to work a little harder to get up to speed. You can only recover that energy if you slow down without braking. If you brake, the extra work you did to get up to the speed you were doing when you started to brake is lost as heat in the brake blocks, and you have to work harder to get up to speed all over again. It's not much, but it can add up over a long ride.

 

[GrasB]

Ah, you have seen me on my way to work then?

Not unless your commute takes you downing Madingley Road, The Backs & Silver street at 12:30 every monday & tuesday...

BTW did you deliberately miss the point of my post?

 

[02GF74]

But both riders will have performed the same amount of work to cover the same distance, regardless. This assumes that you turn the pedals more than once - and if you do, conservation of monentum comes into effect. And even if you did only turn the pedals once, the result would be the same, assuming all else is equal.
.

In an ideal situation were there are no losses and the course is flat and totally straight then that is almost correct as it also assumes that the riders did not use brakes and were ablle to come to a halt exactly on the finish line so they can recover the energy in the rotating mass (fywheel) i.e. conservation of momentum.

you may not live in the real world but all cycle races take place in it - touch the brakes, rider with heavier rims needs to put in more energy to keep up with the other rider, turn a corner same thing again.

PS Are we on page 10 yet?

And where has all the rain predicted by the Met Offivce website gone?

 

[User6179]

Go back to my first post Eddy where I say "better (however you measure that)" i.e. better means different things to different people - if you are not contradicting that, which apparently you are not, what are you saying?

I am saying you are correct if you are comparing like for like ,i.e. two sets of alu aero wheels or two sets of touring wheels or two sets carbon rimmed wheels but like I was trying to say ( badly) that a cheap set of factory wheels could be better than a £1000 pair of wheels depending on purpose of use .

Joe Bloggs could be using a pair of Fulcrum 5s and upgrade to a set of carbon aero Zipp,s and find them to harsh a ride as he is 90kg and not much aero benefit as he spins along about 15mph and concluded the F5s are actually better for his riding style even though the build quality is not as good.

Spending a fortune on a wheel set might not buy you better wheels depending on who you are and how you ride because more expensive wheels for racing bikes usually mean Lighter, less durable , stiffer , harsher ride.

 

[thegravestoneman]

I have had Zonda's (the tubeless ones) for about 3 weeks now I am more than happy with them, before I rode on non-aero sew-ups which weighed in at 300g lighter for what it is worth. The sew-ups were more 'chuckable' on corners but overall the Zonda's are a better ride and will be staying on.

No carbon involved anywhere there so not really what this thread was about.

 

[fossyant]

There are quite a few folk on here that have done their best to explain, but it's not working.

I've ridden lots of different wheel sets, from ultralight alloy rims with tubs, heavier duty rims, carbon deep sections, and disc wheels.

Weight at the rim matters, as does heavier rims for different purposes though. The main reasons for disc wheels, is that they act like a flywheel, great for TT racing. One can argue about aero advantage as the air coming off the bike isn't clean, and manufacturers like zipp have taken into account wind yaw angles etc to develop very quick wheels.

If I was to ride in the hills, I'd not be taking a 'reasonable' (less than £1k) cost set of deep section wheels up there, I'd pick a light set of alloy rimmed wheels. I did a sportive earlier in the year up in the Peaks. It was rather windy up top. Most of the guys with deep section carbon wheels bailed as they couldn't hold the bike. It was bad enough with light semi aero alloy rims.

Jowwy has got the best wheels for all round use - aero and light, but at a cost - you can't top Zipp 202's.

I'm happy with my 28 spoke Mavic CXP 33's on Dura Ace hubs. The hubs aren't light, but are durable (20 years old) but the rim is light for a semi aero wheel. Add in light tyres and latex tubes, this makes a very quick wheel to accelerate, or change speeds - great in the hills, but the pair are about 1800g (because the hubs are heavy).

I've got a set of Hed Jet's (vintage), but I wouldn't bother with these in the hills. They are just as light (titanium hubs from Hope) and the rim is a carbon fairing (like mavic), but the rims are heavier than my alloy rims. Also the constant crazy side winds in the Peaks make them a mare as well as the additional rim weight. On the flat and TT's then the Hed's were the bit of kit I used (for TT's).

The point is, different wheels have a time and place. You have a massive choice and can pick the wheels to suit you and the type of riding.

Rotating weight is different to overall static weight.

 

[VamP]

I am relishing the irony of the fact that all the people on this thread who are so very aware how much faster lighter rims make them are non-racers, while the few racers are all in the meh camp.

I wonder if anyone actually read the Zinn piece that RecordAceFromNew linked to.

Here is a taster:

Lighter bikes are easier to get up hills, but the cost of "rotating mass" is only an issue during a rapid acceleration, and it is small even then.

Anyone who thinks they can tell the difference between the acceleration of their winter wheels and their best wheels, on a pootle ride, is kidding themselves.

 

[Pedrosanchezo]

I am relishing the irony of the fact that all the people on this thread who are so very aware how much faster lighter rims make them are non-racers, while the few racers are all in the meh camp.

I wonder if anyone actually read the Zinn piece that RecordAceFromNew linked to.

Here is a taster:

Lighter bikes are easier to get up hills, but the cost of "rotating mass" is only an issue during a rapid acceleration, and it is small even then.

Anyone who thinks they can tell the difference between the acceleration of their winter wheels and their best wheels, on a pootle ride, is kidding themselves.

You mean you can't tell the difference?

To be fair guys how many people buy/build handbuilt wheels with specifically light rims for rotational gains, whilst climbing? Better still how many people notice the difference?

FWIW i agree that rotational weight at the rim will make for quicker acceleration, that can be quantified, but i am pretty sure it is not measurable by average Joe who is going to be purchasing such wheels from a local wheel builder or Wiggle.

Bottom line though is we all buy add ons for our bikes which are far more bling than do any-thing! If it makes us feel better or provides a placebo effect then maybe it's worth double the price to the individual.

 

[VamP]

You mean you can't tell the difference?

To be fair guys how many people buy/build handbuilt wheels with specifically light rims for rotational gains, whilst climbing? Better still how many people notice the difference?

FWIW i agree that rotational weight at the rim will make for quicker acceleration, that can be quantified, but i am pretty sure it is not measurable by average Joe who is going to be purchasing such wheels from a local wheel builder or Wiggle.

Bottom line though is we all buy add ons for our bikes which are far more bling than do any-thing! If it makes us feel better or provides a placebo effect then maybe it's worth double the price to the individual.

I race crits and cross, the two disciplines with heaviest emphasis on acceleration. I have quite a lot of wheels with different rim weights. Can't tell any difference in the way they accelerate. I am quite attuned to the way different tyres and even inner tubes affect my speed, I can just about distinguish an aero effect of deep sections, but the impact on acceleration is imperceptible.

BTW I love nice wheels, there's a lot to like about modern carbon rims, and my next wheels are going to be just a few grams over 1000g. I expect better performance from them. But I don't really expect them to make me accelerate noticeably faster.

 

[Pedrosanchezo]

I race crits and cross, the two disciplines with heaviest emphasis on acceleration. I have quite a lot of wheels with different rim weights. Can't tell any difference in the way they accelerate. I am quite attuned to the way different tyres and even inner tubes affect my speed, I can just about distinguish an aero effect of deep sections, but the impact on acceleration is imperceptible.

BTW I love nice wheels, there's a lot to like about modern carbon rims, and my next wheels are going to be just a few grams over 1000g. I expect better performance from them. But I don't really expect them to make me accelerate noticeably faster.

I'm a huge fan of nice wheels and tyres also, or what i perceive as nice. I use them for many different disciplines - road racing, hill climbs, TT'ing and recently CX racing. I find this sways me toward good overall wheels rather than a specialist of one area.
I've looked at super light carbon tubs before but stuck with the 50mm's that weigh around 1400 grams. In the end i had decided that the difference would be negligible, in terms of climbing, between the two wheels getting up to speed on an ascent. More importantly, to me, is my fear that they would be a little too flexy under bigger watts, such as climbing out of the saddle and sprinting. For spinning in the saddle the weight reduction from the wheels would be most welcome.

Interested to see how you get on with them. I know a few chinese manufacturers with a decent rep such as Dengfu.

 

[VamP]

Interested to see how you get on with them. I know a few chinese manufacturers with a decent rep such as Dengfu.

I'll do a separate post with end of season summary. They will get thrown into the deep end of the cross season, so any weaknesses will be rapidly exposed. I am quietly excited about them, as if they prove half as good as the press they're getting, they are a VERY affordable route into high performance race wheels, and I'll be getting a whole bunch more for next season.

The ones I'm getting are Far Sports.

 

[Hacienda71]

I'll do a separate post with end of season summary. They will get thrown into the deep end of the cross season, so any weaknesses will be rapidly exposed. I am quietly excited about them, as if they prove half as good as the press they're getting, they are a VERY affordable route into high performance race wheels, and I'll be getting a whole bunch more for next season.

The ones I'm getting are Far Sports.

That link was not routing you to a carbon wheel site..............