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I hear/read everywhere that if you can spend some extra money on the bike, buy better wheels. can someone explain for me why? Is it because they are rotating or are there other comfort factors? thanks

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    I don't say this is a duplicate, but a logical extension to your question is to ask about rims and rim depth (think about when you see time trials, or track, where wheels are often solid disks). There's a good question here (among others) touches this subject. – PeteH Dec 9 '14 at 17:31
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    Wheels are important because the front forks kinda dig into the ground if you don't have them, har har. – David Richerby Dec 9 '14 at 20:01
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    @cherouvim - It would be interesting to somehow do a "blind" test of that. Concert violinists can't tell the difference between a $2000 violin and a $200,000 one. – Daniel R Hicks Dec 14 '14 at 13:58
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    That's what the concert violinists thought. – Daniel R Hicks Dec 14 '14 at 14:27
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    Per the help center: Comments should not be used for “...secondary discussion or debating a controversial point; please use chat instead.” – jimchristie Sep 1 '17 at 14:32
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Wheels and tires are the interface between the bike and the road; and are the parts that take the most stress (wear and tear) along with the bottom bracket. (IMO)

  • lighter wheels will reduce the rotating mass (rotational inertia); you will need less energy to make the wheels accelerate/decelerate.

  • higher quality bearings in the hub will reduce friction.

  • better aerodynamics in the rim and spokes (less energy needed to cut through air)

IMO, In the end it all matters to weight.

If you are doing serious cycling (i.e. keeping time, strava segments, ... ) it might be a good upgrade; but if you are a little less serious about it, maybe just an expensive christmas gift to self. :-)

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    Buy or buy :) that is nice! – Johan Dec 9 '14 at 17:08
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    Don't forget that a tire upgrade brings instant gratification up front as well for not a lot of money. You might not notice a weight difference in other components but going form a cheap OEM tire to a quality street tire which improves rolling resistance or puncture resistance can be a big improvement upfront. – BPugh Dec 9 '14 at 21:08
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    The whole "rotational inertia" thing is bogus. On a bike weight is weight. There is a very slight increase in inertial from having weight on the wheel rim vs elsewhere, but it's miniscule. – Daniel R Hicks Dec 11 '14 at 1:33
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    @ChrisinAK - When you change tires you change tread pattern. I'm guessing your winter tires are thicker and knobbier, making for significantly increased rolling resistance. – Daniel R Hicks Dec 12 '14 at 1:52
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    Tread pattern is actually the same. The main difference is the rim weight/width. – Deleted User Dec 12 '14 at 17:05
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Wheels are an easy upgrade to make as you can put them on your bike immediately with little mechanical hassle.

There are many factors related to a wheel's performance, but the one that makes the greatest difference to energy/power demand, speed and accelerations is aerodynamics. Hence why one of the most popular upgrades is to wheels with better aerodynamic properties. Wheel weight is generally way over rated as a factor in performance, and I'll come back to that later.

Factors other than aerodynamics and weight include:

  • strength
  • durability
  • ability to stay round and true
  • lateral stiffness
  • cost
  • repair-ability and service cost
  • suitability for the purpose/race/riding situation
  • braking demands
  • handling characteristics
  • available tyre choices
  • bearing and freehub quality
  • rules of competition
  • suitability for the bike (e.g. will it fit?)
  • sex appeal / bling factor

and so on.....

Even adding weight to a wheel rim in order to improve aerodynamics is a good trade off. However don't get sucked into thinking that the performance improvement will turn you into a racing star. The performance improvement is incremental, not revolutionary, and other factors are important when training or rolling around town.

While reducing a wheel rim's mass does give you very slight advantage during accelerations (it has no impact on steady state riding), improving the wheel's aerodynamics is by far more important.

A heavier but more aero wheel will still accelerate faster (or require less power to accelerate at the same rate), and it will attain higher speeds (or require less power to sustain any given speed). This is also true even when climbing, except when the climb gets very steep (how steep depends on your individual power, mass and aero properties).

Here is a blog post with more detailed example of the small impact to performance of adding mass to your wheel's rims, and how that extra mass is worth it if it results in better aerodynamics, even for the hardest acceleration scenario there is on a bike, a standing start:

The sum of the parts II

  • The hub is very important too, imo – gaurwraith Sep 9 '16 at 20:24
  • Agree, which is why I mentioned it in the (non-exhaustive) list. – alexsimmons Sep 9 '16 at 22:13
  • Yea, I mean that you lumped it with other minor factors where I would have it in higher regard than aerodynamics – gaurwraith Sep 10 '16 at 10:21
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    Well the OP was asking about racing wheels, not comparing with some old rusty clunkers. As for hillclimbs, aero still matters there too and more than the tiny hub frictional differences between (new) wheels. It depends on gradient and the W/kg of the rider but for a good amateur racer the aero benefits still outweigh wheel weight differences up to gradients of ~7-8%, let alone tiny hub frictional differences. And besides, you present a false dichotomy. One can have aero wheels with good hubs. – alexsimmons Sep 12 '16 at 2:12
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    As for cross winds, wheels perform differently yes, and handling is a factor hence why I stated suitability for the riding situation - but that's not a factor for which hubs play a part. Note that well designed aero wheel rim shapes actually get more aerodynamic with increased yaw angles, not less. IOW their benefit increases with cross winds. At least up to a point where excessive cross winds cause other issues. – alexsimmons Sep 12 '16 at 2:16
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[My knowledge is not racing-specific, but as they say, any time two bicycles are moving in the same direction, it’s a race.]

Hand-built wheels will tend to be stronger and more reliable than machine-built wheels. That is only very loosely true, but the way it was explained to me by an experienced wheelbuilder in a large local shop was that wheelbuilding machines can turn out wheels just as good as hand-built, but to do so the output speed has to be turned way down. This brings up the finished cost of the wheel to a point where the insanely expensive machine has no cost advantage over the human, so is rarely if ever done.

A more rigid wheel will transmit more energy to the ground because any deformation is inherently a loss of energy, or least a diversion of energy away from your goal of going forward quickly.

Lighter wheels give you a large advantage, as rolling weight matters much more than static weight. How much is a matter of some debate, and I find the 2x value given here to be overly pessimistic, but it’s still definitely more than 1x.

Better spokes matter, too. Spoked wheels are an aerodynamic cluste— well, they’re extremely sub-optimal. So more aerodynamic spokes will help considerably. As will lacing patterns with lower spoke count (which also help with weight), although those sacrifice some durability.

Now as to whether all those improvements will help? I am of the opinion that even for those of us who aren’t competing (but see qualifier statement above), anything that makes us feel like we are riding faster and/or with less effort is helpful in that it increases effective endurance. In other words, if you make a cyclist feel faster and/or more powerful, they will tend to ride more, which will, over time, make them faster and/or more powerful.

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    rolling weight matters much more than static weight -- It matters a little more, and only for acceleration. Weight on wheel vs frame has no effect at all on rolling resistance. – Daniel R Hicks Dec 11 '14 at 1:36
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You win non-TT bike races by being able to accelerate just that little bit much more than your competition. 99.9% of the time you are riding exactly the same speed as everyone else, what makes the difference between winning and losing is your ability to accelerate just a bit better than your competitors.

Humans are very low power engines. Since F = MA, one of the easiest ways to increase A is to decrease M. Low weight, low drag wheels will help you accelerate faster. Since wheels are rotational mass, you get a bigger bang for your buck in reducing their weight.

Bike racers obsess over the weight of gear to improve their ability to get to speed, reducing weight generally doesn't help your average speed much ( except when climbing a long hill).

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    This isnt really correct. Numerous academic papers have identified that in the vast majority of racing scenarios, the impact of aerodynamics substantially exceeds the impact of weight. Even the minor benefit gained from spinning up a lighter wheel out of a corner is negated rapidly by the aerodynamic inefficiency. Unless youre riding up and down <insert mountain range here> all day, really lightweight wheels are just something to brag about in the pub ;) – richzilla Feb 14 '17 at 13:20
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Less rotational mass can be felt immediately, even 200 grams. It would be incredibly evident right away in acceleration. The number one thing I hear people say after buying stock bikes is they got a new wheelset and "it feels like a new bike". Now, it's been proven why complete with formulas.

https://www.wired.com/2016/06/cycling-physics-extra-mass-bike-wheels-enemy/

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    Umm... your link says exactly what Daniel R Hicks wrote above, rotational mass matters a little more - but only during acceleration. I'm editing your answer to remove the ad hominem. You may still be downvoted for other reasons, but at least it isn't for an ad hominem. – RoboKaren Feb 14 '17 at 1:10
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    As a physicist myself, I couldn't stop giggling when I read the rotational mass weight weenies (i hope that's not ad hominem) theories on a cycling blog the first time. (Assuming not a lot of people here are doing 1 km track time trials where it might matter in the <1% area.) – gschenk Feb 15 '17 at 19:44
  • Welcome to Bicycles @Crankdango. As with all new members we recommend that you take the tour to make best use of the site, and since you're answering see How to Answer also. Enjoy – andy256 Feb 15 '17 at 22:34

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