I have two wheels with the same cassette. When I put wheel #1 into the bike, spin it, I rotates well and stops slowly. For wheel #2, it rotates and then stops faster than wheel #1. Can I assume the hub on wheel #1 is better and faster? Is there such as a thing as a faster hub and thus a faster bike?

This comes up so often it deserves a sticky.

The differences in drag related to how long a wheel spins off the bike are miniscule. They have about as close to zero as possible effect on the drag or speed of a bike.

It's a simple question of inertia, compare the mass of the wheel to the 200# bike and rider as a unit.

There is such a thing too tight axle bearings, have you felt the turn of the axle with the wheel off the bike, by twiddling them with your fingers?

From your description of the relatively sudden stop my bet is that you have an out-of-true rim rubbing the brake rather than too tight bearings on your hub. Either way, I'm agreeing with FBinNY that it isn't affecting your bike speed significantly. If it was my bike, though I'd still fix it.

I've found that factory wheels often have the hub bearings adjusted way too tight. You are likely seeing that difference. However, it could be the difference between loose bearings and cartridge bearings or a well sealed hub compared to a poorly sealed hub. Or even the difference in freehub pawl drag.

If it is considered that the drive train is connected during this testing, there may be differences between the freehub ratcheting mechanisms that cause the rotating differences you are seeing.
I recently built a wheel with an unused Ritchey hub whose freehub mechanism was fairly stiff compared to that of the previous hub. The only comparison in performance was how fast I coasted down even a shallow grade compared to my riding companions whom I had always outcoasted. I noted no difference with the new hub............

If it's really tight when you spin it by hand, (holding the axle in your hand for example) then sure loosen up the cone. That's just common sense, but counting spins until it stops isn't a test for friction.

Spinning the wheel without weight on the axle does not translate into spinning while loaded. The test doesn't tell you anything. It would be better to find a slight down-slope, coast from a stop and see how far you go.

FWIW, I just replaced a rear wheel because my lbs said the freehub body was shot and could not find a replacement (too old). The difference between that wheel and the new one in terms of pedaling effort is substantial. I was definitely getting a lot more resistance or drag off the old hub. Maybe it only applies is the hub is "broken" but the difference has allowed me to cycle at my preferred cadence in one higher gear for the same effort.

In general, no. Mechanical resistance is a small portion of the drag on you and the bike and it becomes proportionally less with greater speed. Here's a nice graph:

(From Bicycle Drag Force Formulas )



If you want to go faster, work on these things in this order:
1. Your physical condition
2. Your aero position
3. Your bike's implementation

Unless the bearings were seriously overtightened the hub is not the proper explanation for the difference. One gear higher is easily more of a difference than the contribution of the entire drivetrain and bearings.

I'm not a mechanic, so it's just my observation. The only thing that changed was a new hub. The old one was making all kinds of noises, and sometimes vibrations felt in the pedals. The lbs did not explain exactly how it was "shot". But I usually think if there is vibration then there is also some kind of rubbing or resistance? It definitely spins better when on the bike stand - the old wheel rotated a few times then slowed and stopped, the new one spins a long time. No brake adjustments, and the old wheel had been adjusted by the lbs to run as good as it could.
If it was not the hub, then I magically gained some muscle

A hub that makes "all kinds of noises" obviously could have a problem serious enough to slow one down. Again, under normal conditions nobody can tell the difference between hubs while riding

+1 (and repeating myself) that the perceived difference in the hubs is meaningless real world riding.

But, since I know that people are obsessive and can't leave well enough alone, here's things to consider.

1- The differences could be inherent in the design, such as a freewheel ratchet that's a bit stiffer.
2- Viscous drag from more or stiffer grease
3- Seal drag, from tighter or dry seals, or no seals on one.

4- Bearing friction, which is more complex, and which I mention only because others reference tightly adjusted hubs. This is tricky, because an improperly loose hub will have less friction when spinning in your hand, yet more once it's loaded with your weight. So, before you decide to readjust the bearings stop and think.

Spin the axle between your fingers, and feel the drag. Grease and seal drag are very smooth and silky (unless there's dirt contamination). Bearing drag from a tight bearing, feels "mechanical" with a sense of metal to metal contact and vibration. However, a properly adjusted hub has a bit of preload, because that's what the design calls for, and so you should feel it slightly.

Component makers set the hub bearings on the tight side for two reasons.
1- loose bearings are more of a problem, so they err tight. Also it's difficult to properly align a wheel if there's any hub play.
2- a hub adjusted to the tight side will wear to correct tolerance, whereas a loose hub only gets worse.

Without knowing any specifics and having the ability to see if there might be a problem, I repeat my earlier advice.

STOP OBSESSING and ride the bike.

Okay, I get that but then I have to wonder why people spend more money on certain hubs. I am going to try my hand at building wheels and, if this is true, does it matter if I buy a cheaper hub or a more expensive one? What's the benefit of more expensive hubs then?

They lighten the wallet more, thus putting more profit in the bike shop's pocket. If you're building your own wheels, "average" hubs will perform as well as "boutique" hubs.

I've built my own wheels for 35+ years. Most of the time I use mid-range parts: Shimano Deore, 105, or Ultegra. These are the sweet spot, IMO, between cost and durability.

I only mentioned the hub bearings because it's a thing you want to check. If they are too tight, or loose, it will lead to problems down the road.

Depends on the end user requirements/preferences. Some look for weight savings or faster pawl engagements (3+ pawls). Others want bragging rights or like noise.

Sometimes you don't have a choice if you want a hub that isn't 32h or 36h. Then you may be limited to either generic hubs or high end (expensive) hubs.

You get parts that cost more to make .. little things like hardened steel cones and Races, polished to a Mirror like surface ..

Vs Good enough to do the job , for Most Peeps..

Quite common on some wheels. Mavic Ksyrium SL seals swell and can drag.

Acknowledging your admonition to not be obsessive, I've trimmed Ksyrium freehub seals slightly with a good scissor.


-Tim-

Are these bare wheels or with identical tires & tubes mounted?
A heavier tire could make it rotate longer.

WRONG. The hub that has the extra drag probably has DAMAGE, and/or has been improperly adjusted. The ONLY thing, other than bearing condition/adjustment/grease, that might cause higher drag would be any rubber seals on the hub.

as to MOMENTUM... the rim and tire/tube weight lends momentum to the wheel when spun in-frame... I always test for bearing tension with the wheel OUT of the frame, and tire/tube removed... i lay the axle on two open fingers after spinning it up... if the axle wants to turn on my open fingers, it gets readjusted or rebuilt as needed.

"slightly tight"... this will cause heat buildup during use... the product of heat is increased friction... the heating can, and DOES, cause melting of the cones' hardened surface! Ever taken a close look at the "worn" cones with pitting going on? yep, MELTED surfaces. Heat and pressure causes GALLING of the surface. Rust can also promote galling... once again, the extra friction from the rust pitted surface causes heat to build up... add pressure, more heat gets produced, expansion of parts involved further increases heating... whalla! time to replace cones and balls....

A properly adjusted set of hubs does in fact effect your "speed", since a dragging hub bearing set WILL slow acceleration, and yes, TOP SPEED. a bit of fresh, light grease, and proper adjustment makes for a happy, FASTER, rider. Rotating mass also plays into enjoyment... Note all those fancy bikes with carbon fiber and aluminum bits all over the place on them... there are good reasons for those pieces!

Grease... too heavy of grease viscosity will cause issues, too... "FLOWBACK" is needed to keep grease on the bearing surfaces... friction sets in... heat builds... guess the rest... i use a bicycle specific grease... it is light enough to allow flowback, without getting too thin during use.

Reduce any ROTATING MASS to improve acceleration... and get those bearings right, if you have the tools and skills needed.

^ ^ Wow, just Wow. The paragraph following "WRONG" does nothing to refute the quote. I would welcome any documentation that can support the claims/beliefs above about melting of cones and any significant effect of minor hub adjustment or weight differences on speed.

As has been said in many different ways, above, the difference between two properly adjusted, lubricated and functioning bearings should be nearly nil. And if a bearing was poorly lubed or maladjusted enough to notice, you'd .... well, you'd notice. Grinding in the bearings, or tough to turn the axle at all. And if the bearing was adjusted to be a bit too tight (to much "preload", in the parlance), and this created friction, it would heat up the axle, lengthening it a bit, to reduce the preload. If the axle does not offer much friction when turned with your fingertips, it's probably not too bad. Seal friction can offer a bit of resistance, and is more pronounced in new bearings.

I guess your question is one of degree. If you spin one wheel and it spins for two minutes, and you spin the other wheel and it goes for one minute, but both wheels appear to have smooth function, read what FBinNY says above: stop obsessing and ride... If the second wheel stops after spinning an eighth of a turn, with a grinding sound... Well, yeah, that will affect your speed.

+1

Hey! I resemble that remark! Seriously, this is a good comment for me to keep in mind in responding to posts here.

+1

OK, that's kinda useful as it shows relative impact of wind, tire, and drivetrain for presumably a well-tuned and spec'd racing bike. What OP is really more interested in is how the drag he's perceiving fits into the overall scheme of things.

I agree though, that drag is very low on the impact list. Like if you have knobby tires for road riding, the "Tire" curve on that graph would jump up to rival the wind curve, at least for some range of speeds.