Fast hubs ? possible ?
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It's amazing that these vastly more expensive wheels are no better than the cheapo's that are sold with the bottom end bikes ... it makes you wonder why we bother at all - being that it makes no difference ....
Wheels can make a (small) difference, but not by the hubs.....the form/weight of the rims and form and number of spokes can cause small aerodynamic differences.
I really don't bother at all about the hubs, even the crappiest hubs will not have any significant difference on the performance of the cyclist.0 -
The problem of reducing the all issue to aerodymanics and tyres rolling resistance is that it doesn't account for empirical evidence of some wheels being quicker than others downhill given same tyres and maybe worse aerodynamics, which is a fact of life... so you have to "drag in bearings/freehub drag" to try to make sense of the evidence
I rather believe in Karma of Superwheels or the power of shiny decals than difference in hub drag.
I have not knowledge of any evidence (real or anecdotic or whatever) of some wheels being quicker by something else than aerodynamics and rolling resistance.
The position of the head (look down or forward) alone makes far more difference than any possible difference in hub bearings.0 -
You've said you are as aerodynamic as a brick - from the scant evidence we have here it sounds like your pal is less aero than you. Is his position higher ? Wider ? Knees out ? His drafting skills not as good as yours ?0
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It's amazing that these vastly more expensive wheels are no better than the cheapo's that are sold with the bottom end bikes ... it makes you wonder why we bother at all - being that it makes no difference ....
Wheels can make a (small) difference, but not by the hubs.....the form/weight of the rims and form and number of spokes can cause small aerodynamic differences.
I really don't bother at all about the hubs, even the crappiest hubs will not have any significant difference on the performance of the cyclist.
So all this carp about ceramic bearings .... not worth it then ...
ok ...
I'm not an expert in bearings, but I do have experience of bearings under load - far higher load than you'll find on a bike - and the quality and type of bearings makes a HUGE difference - you may not think it makes any difference, but any moving part is going to have drag - drag = lost watts as it's turned into heat - you may or may not notice it - it depends on how big a percentage that lost power is compared to other losses ... but it'll play a part ...0 -
I remember seeing a video on this site, I think, where someone flicked the pedal on Contador's bike and it just span and span for what seemed like a minute... Mechanic wouldn't reveal what the secret was but if the bearings can make such a big difference to summat like that - and are deemed worthy use of a busy team mechanic's time - then surely their quality and maintenance in a hub is even more significant?Job: Job, n,. A frustratingly long period of time separating two shorter than usual training rides0
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The secret of Contador is: leave the seals out and lube with oil.
Like weight weenies , some are dragweenies.
Sometimes when I'm bored (rare) I read a couple of minutes on Weightweenies, always good to cheer one up because of the ridiculous nonsense sold there.
I've made my points, anyone who looks for speed with hubs has my blessings....0 -
So all this carp about ceramic bearings .... not worth it then ...
ok ...
I'm not an expert in bearings, but I do have experience of bearings under load - far higher load than you'll find on a bike - and the quality and type of bearings makes a HUGE difference - you may not think it makes any difference, but any moving part is going to have drag - drag = lost watts as it's turned into heat - you may or may not notice it - it depends on how big a percentage that lost power is compared to other losses ... but it'll play a part ...
A huge difference of a tiny part is still tiny.
Assume the drag of hub bearings is 0,1W % (just an example, you may propose something else) on a unloaded wheel to keep it turning (in vacuum of course) at 3000 RPM.
Fully loaded , the resistance raises with 900% and is now 1W.
The power needed to roll 60 km/h loaded with bike+cyclist (not in vacuum...) is 500W (total drag is 500W)
So the difference in drag is 0,2% which IMO will not lead to a noticable difference in descent speed.0 -
You keep saying you're not aero, but only refer (subjectively) to your weight. Depending on how tall, wide you are, the clothes you wear, how you ride and the geometry of your bike, I'd be willing to bet aero could still be a factor - especially if your mates ride very differently.0
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How many spokes do you have in your wheels compared to your riding partners?
As others have said, the major drag load on a spinning spoked wheel is aerodynamic.
Consider that the top of the wheel has an airspeed of twice that of the bike. And that aerodynamic power consumption increases as a cube of airspeed (force increasing as a square law).
The aerodynamics of spoked wheels famously vary enormously, particularly between wheels from cheaper brands; it is not cost-effective to conduct fluid modelling trials on anything but ultra-high-end wheels.
There are also very complex and difficult-to-model fluid windage characteristics around the fork and chainstays/seatstays.
If there is a significant difference in hub drag load then it's more likely to be a poor setting of axle axial preload in your riding partner's hubs than any particular low drag characteristic in your hubs IMO.- - - - - - - - - -
On Strava.{/url}0 -
Could be down to the fact your on 28mm tyres, which means you have larger diameter wheels (because 28mm isn't just wider but taller, giving you a larger overall circumference). Put it another way, imagine fitting 26" or 24" wheels to your bike, you'd probably not be able to coast as quickly as someone with 700c wheels because overall circumference does affect how much resistance you experience. Try riding a bike with 36" wheels, you can coast along over everything without losing speed. And 28mm tyres will absorb more road buzz (which is a form or resistance) than skinnier tyres. The heavier tyres will add more centrifugal force to the wheels also.
Have you tried swapping bikes with one of your heavier mates and seeing if they coast downhill as quickly you?0 -
You have to love internet forums.A guy asks if his hubs are making him faster and the overwhelming answer is no but the op decides to take no notice what so ever. Why do you think bike company's spend fortunes on developing aero bikes and aero equipment?The wheels arnt the only moving part,the whole bike and rider are moving as one through the air.0
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You have to love internet forums.A guy asks if his hubs are making him faster and the overwhelming answer is no but the op decides to take no notice what so ever. Why do you think bike company's spend fortunes on developing aero bikes and aero equipment?The wheels arnt the only moving part,the whole bike and rider are moving as one through the air.
Well, quite a debate in the few days I've missed......
Re the above, - as the OP, what says I've taken No Notice ???
The facts are still thus.......and case in point Friday evening, as per our usual rides:
One friend is on a Spec Allez, which is lower front end than my Roubaix, so should in theory sit him more aero on the bike. However, he's perhaps 10kg lighter than me, so that accounts for why I'm always quicker downhill than him, Gravity works in my favour, that part of physics I understand.
Friend 2 is perhaps 5kg heavier than me, and wider than me, and riding a Spec Secteur, which I believe is same Geometry as my Roubaix, or very similar, but despite weight 'advantage' when going downhill, isnt as fast. That said, he's more cautious, so perhaps touches his brakes more than I.
Friend 3, who wasnt out this week, is about same weight, riding a new BMC Gran Fondo, which again I think is similar geometry to a Roubaix, but again, I am clearly faster rolling downhill than.
By downhill, lets clarify, - we are'nt drafting, or racing, just freewheeling down the many rolloing sectors of the East Yorkshire countryside, nearly always on the hoods, and pretty much all wearing same gear, - ie Bibs/jersey, Helmet & shades, no flappy clothing to slow us particularly, and no discernable difference in posture, and of the bunch, there's only FRiend 2 thats perhaps 'stockier' than I.
I'm a stocky built 5'11', 44" Chest etc.....and no racing snake. Friend 2 more so, Friend 3 less so but taller, and as Friend 1 is lighter, I'll leave him out of the equation.
My wheels & Hubs are Ksyrium Elites, 2yrs old, and the Spokes are a flat spoke, - perhaps these are the more aero advantage and the cause of my speed ?
Or, its the Hubs........'cos there certainly aint anything about me or my riding style that is !
I aint complaining, or arguing, just genuinely curious as to the cause :-)0 -
Swap the wheels around with your friends. Then set off from exactly the same speed at the top of a hill, side by side, wearing largely identical clothing, identical helmets, identical tyres, identical riding postions, identical frames and finishing kit. Then come back to this thread.
I'm sure you understand what I'm getting at.0 -
Mavic use rather large bearings and a freehub with only two pawls, which sit on the axle rather than on the freehub body... there might be less drag in this system, which would explain why they have stuck to it for as long as anyone remembers.
Aerodynamically the R-SYS should be dreadful, yet they are fast wheels downhillleft the forum March 20230 -
CUT
Or, its the Hubs........'cos there certainly aint anything about me or my riding style that is !
I aint complaining, or arguing, just genuinely curious as to the cause :-)
Definately the hubs, as you describe only half a page of possible other more likely explanations.....
Never guessed there could be a market for fast hubs, but you opened my eye for a hole in the market.
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Tyres will be a factor. Pressure, profile and type. Tubs and tubeless will roll faster than clinchers, fatter tyres will roll faster at the same pressure. Bearing resistance could make a difference, but I'd be surprised if it was that material. Aero will trump all of that, and weight could trump aero, depending on the disparity.0
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Personally I think hubs make a slight difference, both my King r45 and Da9000 hubs spin feel faster descending. How marginal it is I've no idea. I would say it palls into insignificance when I compare my 50mm deep wheels to my c24's, the difference deep wheels make is very noticeable. If you want to improve descending speed then aero is the way to go.0
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but you opened my eye for a hole in the market.
The market has no holes, only gaps...
left the forum March 20230 -
It's all about aero here.
Are your handlebar widths the same? This is a big factor in aero performance.
2 riders can look to have similar positions from the side, but look at them from the front, and the guy on 38cm bars is a lot more aero than the guy on 44's.
A lot of the pro peloton has gone for narrow bars recently.
I went from 42 to 38cm bars and it's been the best thing I ever did. I am way more aero than any of our 30 or so Sunday group (I always was, but now even more so!)0
